Seat with side support control for vehicle responsive to distance and position in curve roads

This application is based on and claims priority under 35 U.S.C. §119 to Japanese Patent Application 2006-313814, filed on Nov. 21, 2006, the entire content of which is incorporated herein by reference.

The present invention relates to a seat apparatus for a vehicle that controls a side support portion depending on a road shape.

A vehicle controlling apparatus disclosed in JP2005088834A includes a suspension control device and a navigation device. The navigation device determines that the vehicle is driven on a winding road that has, for example, two curves (e.g., a previous curve and a current curve) including a straight portion therebetween, based on electronic map data, and the suspension control device controls a suspension on the basis of the determination of the navigation device. In his configuration, even when the navigation device determines that the vehicle is driven on the straight portion, the suspension is controlled. In the light of this configuration, it is conceivable that a side support portion may be controlled in the same manner as the suspension being controlled by the vehicle controlling apparatus. As a result, an occupant of the vehicle seat may not feel frequent actuations of the supporting operation.

However, if the side support portion is controlled in the same manner as the suspension control by the vehicle controlling apparatus, when the vehicle does not have the navigation device, or when the vehicle having the navigation device is driven on a road where a GPS sensor of the vehicle does not receive signal correctly, the side support portion may not be controlled appropriately.

On the other hand, a seat apparatus for a vehicle disclosed in JP2750943 is well known. When vehicle lateral accelerations are continuously detected, the seat apparatus determines that the vehicle is driven on a road having plural curves, such as a winding road, and then a supporting operation is executed. During the supporting operation, the seat apparatus is controlled in order to retain a side support portion to a position where a human body is supported thereby (hereinbelow, referred also to as a supporting position). According to the seat apparatus disclosed in JP2750943, the side support portion is retained to the supporting position without depending on an electronic map data. As a result, an occupant of the vehicle seat may not feel frequent actuations of the supporting operation.

However, because the seat apparatus disclosed in JP2705943 determines that the vehicle is driven on the winding road when the lateral acceleration is continuously generated at the vehicle for a certain time period, even when it is determined that the vehicle is driven on another winding road, the seat apparatus may or may not continuously retain the side support portion to the supporting position when a vehicle speed varies.

A need thus exists for a seat apparatus for a vehicle which is not susceptible to the drawback mentioned above.

According to an aspect of the present invention, a seat apparatus for a vehicle including a driving means for operating a side support portion in accordance with a road shape, includes a sensor for detecting that the vehicle is driven on a curve of the road shape, a distance between curves calculating program for calculating a distance between curves on the basis of the detected result of the sensor, the distance between curves being a distance between an ending point of a previous curve, on which the vehicle had been driven, and a starting point of a current curve, on which the vehicle is currently driven; and a control state determining program for determining a control state of the vehicle on the basis of the distance between curves calculated by the distance between curves calculating means, the control state being set to one of an unexecuted state, an executed state and a standby state, wherein, in the unexecuted state, it is determined that the vehicle is not driven on continuous curves, in the executed state, it is determined that the vehicle is driven on the continuous curves, and in the standby state, it is determined that the vehicle is possibly driven on the continuous curves, the control state is changed from the unexecuted state to the executed state via the standby sate, and the control state is changed from the executed state to the unexecuted state via the standby sate; wherein the control state determining program, setting the control state to the standby state, when the vehicle is driven on the current curve, after the vehicle, which was in the unexecuted state, was driven on the continuous curves, the continuous curves being connected by a distance between curves, and when the control state determining program detects a case where the distance between curves is a first threshold or less, calculates a number of the continuous detections, and determines that the number of detections reaches a first criterial number, setting the control state to the executed state, when the vehicle is driven on the current curve, after the vehicle, which was in the standby state, was driven on the continuous curves, the continuous curves being connected by a distance between curves, and when the control state determining program detects a case where the distance between curves is a second threshold or less, calculates a number of the continuous detections, and determines that the number of detections reaches a second criterial number, setting the control state to the unexecuted state, after the control state was set to the standby state while the vehicle was driven on the previous curve, and when the straight portion driving distance between the ending point of the previous curve and a current position is larger than the second threshold, setting the control state to the executed state when the vehicle is driven on the current curve, after the vehicle, which was in the standby state before the vehicle is driven on the current curve, was driven on a straight portion between a starting point of the standby state and a starting point of the current curve, and when a straight portion driving distance of the straight portion being a third threshold or less, setting the control state to the unexecuted state when a straight portion driving distance between the starting point of the standby state and the current position is larger than the third threshold, and setting the control state to the standby state after the control state was set to the executed state while the vehicle was driven on the previous curve, and a straight portion driving distance between the ending point of the previous curve and the current position is larger than a fourth threshold; and the driving means operating the side support portion so as to be retained to a supporting position when the control state of the vehicle is set to the executed state.

The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawings, wherein;

FIG. 1 illustrates a diagram indicating an oblique perspective view of a seat apparatus according to the first and second embodiments;

FIG. 2 illustrates a diagram indicating a flat view of a seat apparatus according to the first and second embodiments;

FIG. 3 illustrates an electrical schematic diagram of the seat apparatus according to the first and second embodiments;

FIG. 4 illustrates a chart indicating control states according to the seat apparatus of the first and second embodiments;

FIG. 5 illustrates a diagram indicating a road on which the vehicle is driven according to the seat apparatus of the first and embodiments;

FIG. 6 illustrates a flowchart indicating a side support control program according to the seat apparatus of the first and second embodiments;

FIG. 7 illustrates a flowchart indicating a curve driving program according to the seat apparatus of the first and second embodiments;

FIG. 8 illustrates a flowchart indicating a straight portion running program according to the seat apparatus of the first and second embodiments;

FIG. 9A illustrates a graph indicating a lateral acceleration according to the seat apparatus of the first and second embodiments;

FIG. 9B illustrates a graph indicating the control state according to the seat apparatus of the first and second embodiments;

FIG. 9C illustrates a graph indicating the control level according to the seat apparatus of the first and second embodiments; and

FIG. 10 illustrates a flowchart indicating a control forcible termination program according to the seat apparatus of the second embodiment.

Embodiments of a seat apparatus for a vehicle (hereinafter referred to simply as a seat apparatus) related to the present invention will be described in accordance with the attached drawings. As illustrated in FIG. 1 , a seat apparatus of a first embodiment includes a seat slide device 10 and a seat 13 . The seat slide device 10 includes, for example, a pair of lower rails 11 and a pair of upper rails 12 supported by the lower rails 11 so as to be slidable thereon. The lower rails 11 are fixed on a floor 90 so as to extend in a front-rear direction of the vehicle. Specifically, the seat 13 includes a seat cushion 14 on which an occupant is seated, and a seat back 15 that supports the occupant's back. Further, a right side support portion 16 and a left side support portion 17 are provided at a right and a left portions of the seat back 15 respectively for stabilizing a posture of the occupant by pressing the upper body of the occupant on its sides. Additionally, a right motor 26 and a left motor 27 are provided at a right and a left portions of a seat frame 18 respectively. Each of the right and the left motors 26 and 27 includes a reduction mechanism. Furthermore, a right support frame 16 a and a left support frame 17 a are adapted to be pivoted by means of the right and the left support motors 26 and 27 respectively. Both right and left support frames 16 a and 17 a are pivoted by both right and left motors 26 and 27 being driven respectively, and therefore both right and left side support portions 16 and 17 are moved to be in an opened position, which is indicated with a solid line, and to be in a closed position, which is indicated with a chain double-dashed line illustrated in FIG. 2 . The right side support portion 16 and the left side support portion 17 each serves as a side support portion, and the right and left motors 26 and 27 each serves as a driving means.

FIG. 3 is a chart illustrating electric connections of the seat apparatus. As illustrated in FIG. 3 , sensors such as a vehicle speed sensor 22 , a lateral acceleration sensor 23 and a steering angle sensor 24 are connected to a side support electronic control unit 20 (hereinafter referred to as a side support ECU 20 ). The lateral acceleration sensor 23 detects acceleration generated at the vehicle in a lateral direction thereof when the vehicle turns the curve. In this configuration, a detecting signal detected by each of the vehicle speed sensor 22 , the lateral acceleration sensor 23 and the steering angle sensor 24 is inputted to the side support ECU 20 . Furthermore, the right motor 26 , the left motor 27 , a right rotary encoder 28 and a left rotary encoder 29 are connected to the side support ECU 20 . In this configuration, the side support ECU 20 outputs driving signals to the right and the left motor 26 and 27 . Further, the right and the left rotary encoders 18 and 29 output location signals (feedback signals) for successively feeding back positions of the side support portions 16 and 17 until the side support portions 16 and 17 are retained to a target closing position.

FIG. 4 illustrates a diagram indicating a changing manner of the controlling state. The controlling state is determined on the basis of a road shape on which the vehicle is driven. The side support control program includes three control states; an unexecuted state ST 1 , a standby state ST 2 and an executed state ST 3 . The unexecuted state ST 1 is a control state where the side support ECU 20 determines that the vehicle is not driven on continuous curves, the standby state ST 2 is a control state where the side support ECU 20 determines that there is a possibility that the vehicle is driven on the continuous curves, and the executed state ST 3 is a control state where the side support ECU 20 determines that the vehicle is driven on the continuous curves. Further, the control state can be changed between the unexecuted state ST 1 and the standby state ST 2 , and between the standby state ST 2 and the executed state ST 3 . The control state cannot be changed from the unexecuted state ST 1 directly to the executed state ST 3 , and from the executed state ST 3 directly to the unexecuted state ST 1 . In other words, the control state can be changed between the unexecuted state ST 1 and the executed state ST 3 via the standby state ST 2 .

The standby state ST 2 will be explained in detail. As mentioned above, the standby state ST 2 is a control state where the side support ECU 20 determines that there is a possibility that the vehicle is driven on the continuous curves. After the control state is changed from the unexecuted state ST 1 to the standby state ST 2 , the side support ECU 20 detects a case where the distance between curves is a second threshold or less, calculates a number of the continuous detections, and determines whether or not the number of detections reaches a second criterial number. If the side support ECU 20 determines that the number of the continuous detections reaches the second criteria number, the control state is changed from the standby state ST 2 to the executed state ST 3 . Accordingly, the standby state ST 2 could be considered as a control state where the side support ECU 20 determines that there is a possibility that the vehicle is driven on the continuous curves. Further, after the control state was changed from the executed state ST 3 to the standby state ST 2 , the side support ECU 20 determines whether or not a distance between a starting point of the standby state ST 2 and a starting point of the current curve is equal to or less than a third threshold. If the side support ECU 20 determines that the distance is equal to or less than the third threshold, the control state is changed to the executed state ST 3 . Accordingly, the standby state ST 2 could be considered as a control state where the side support ECU 20 determines that there is a possibility that the vehicle is driven on the continuous curves.

It is assumed that a vehicle is driven on a road illustrated in FIG. 5 in a vehicle moving direction indicated with an arrow. In FIG. 5 , P 1 indicates a starting point of a curve C 1 , P 3 indicates a starting point of a curve C 2 , P 2 indicates an ending point of the curve C 1 , and P 4 indicates an ending point of the curve C 2 . Other portions of the road straight portions. When the vehicle is driven on the curve C 2 , the curve C 1 is indicated as a previous curve, the ending point P 2 is indicated as an ending point of the previous curve, the curve C 2 is indicated as a current curve, the starting point P 3 is indicated as a starting point of the current curve, and a distance between the ending point P 2 of the previous curve C 1 and the starting point P 3 of the current curve C 2 is indicated as a distance between curves. On the other hand, when the vehicle is passing a point P 5 of the straight portion, the point P 5 is indicated as a current position of the vehicle, the curve C 2 is indicated as a previous curve, the ending point P 4 is indicated as an ending point of the previous curve, the distance between the ending point P 4 of the previous curve C 2 and the current position P 5 or a distance between the starting point of the standby state ST 2 on the straight portion and the current position P 5 is indicated as a straight portion driving distance.

The retaining control of each of the right and left side support portions 16 and 17 will be explained in accordance with a flowchart of the side support control program illustrated in FIG. 6 . The side support control program is repeatedly executed each predetermined time by using the self directed control program. When the side support control program is executed, in Step S 1 , the side support ECU 20 determines whether or not the vehicle is driven on the curve C 2 . At this point, the starting point P 3 of the curve C 2 is determined on the basis of a lateral acceleration detected by the lateral acceleration sensor 23 . Instead of the lateral acceleration sensor 23 , the starting point P 3 may be detected on the basis of the lateral acceleration calculated using a steering angle detected by the steering angle sensor 24 and a vehicle speed detected by the vehicle speed sensor 22 . If the side support ECU 20 determines that the vehicle is driven on the curve C 2 (YES), the side support ECU 20 proceeds to Step S 2 , and if the side support ECU 20 determines that the vehicle is not driven on the curve C 2 (NO), the side support ECU 20 proceeds to Step S 3 . After Step S 2 and Step S 3 , the side support control program is terminated.

In Step S 2 , a curve driving program indicated by a flowchart illustrated in FIG. 7 is executed. In this case, the curve C 1 indicates a previous curve, the ending point P 2 indicates an ending point o the previous curve, the curve C 2 indicates a current curve, the starting point P 3 indicates a starting point of the current curve, and a distance between the ending point P 2 of the previous curve C 1 and the staring point P 3 of the current curve C 2 indicates a distance between curves. When the curve driving program is executed, in Step S 20 , the side support ECU 20 calculates a distance between curves, specifically, the side support ECU 20 calculates a distance between the ending point P 2 of the previous curve C 1 and the starting point P 3 of the current curve C 2 . The distance between curves is calculated on the basis of the vehicle speed and a driving time detected by the vehicle speed sensor 22 . Hereinafter, the distance is calculated on the basis of the vehicle speed and the driving time detected by the vehicle speed sensor 22 . Step S 20 serves as a distance between curves calculating means.

In Step S 21 , the side support ECU 20 checks a current control state. If the current control state is the unexecuted state ST 1 , the side support ECU 22 proceeds to Step S 22 , if the current control state is the standby state ST 2 , the side support ECU 20 proceeds to Step S 24 , and if the side support ECU 20 is the executed state ST 3 , the side support ECU 20 proceeds to Step 27 .

In Step S 22 , the side support ECU 20 detects a case where the distance between curves calculated in Step S 20 is a first threshold or less, calculates a number of the continuous detections, and determines whether or not the number of detections reaches a first criterial number. If the side support ECU 20 determines that the number of the continuous detections reaches the first criteria number (YES), the side support ECU 20 proceeds to Step S 23 . On the other hand, if the side support ECU 20 determines that the number of the continuous detections does not reach the first criterial number (NO), the side support ECU 20 terminates the curve driving program.

In Step S 23 , the side support ECU 20 sets the control state to the standby state ST 2 and terminates the curve driving program. This example corresponds to a case where the vehicle is driven on the current curve C 2 , after the vehicle, which was in the unexecuted state ST 1 , was driven on the continuous curves for the first criterial number, the continuous curves being connected by a distance between curves that is the first threshold or less. For example, if “2” is set to the first criterial number, this example corresponds to a case where the vehicle is driven on the current curve C 2 , after the vehicle, which was in the unexecuted state ST 1 , was driven on the continuous curves two times.

In Step S 24 , the side support ECU 20 detects a case where the distance between curves calculated in Step S 20 is a second threshold or less, calculates a number of the continuous detections, and determines whether or not the number of detections reaches a second criterial number. If the side support ECU 20 determines that the number of the continuous detections reaches the second criteria number (YES), the side support ECU 20 proceeds to Step S 27 . This example corresponds to a case where the vehicle is driven on the current curve C 2 , after the vehicle, which was in the standby state ST 2 , was driven on the continuous curves for the second criterial number, the continuous curves being connected by a distance between curves that is the second threshold or less. For example, if “2” is set to the second criterial number, this example corresponds to a case where the vehicle is driven on the current curve C 2 , after the vehicle, which was in the standby state ST 2 , was driven on the continuous curves two times. On the other hand, if the side support ECU 20 determines that the number of the continuous detections does not reach the second criterial number of times (NO), the side support ECU 20 executes Step S 25 . In this configuration, because the second threshold is set to be larger than the first threshold, the control state changes from the unexecuted state ST 1 to the standby state ST 2 easier than changing from the standby state ST 2 to the executed state ST 3 . Thus, the continuous curves can surely be detected.

In Step S 25 , the side support ECU 20 calculates the straight portion driving distance from the starting point of the standby state ST 2 to the starting point P 3 of the current curve C 2 . In Step S 26 , the side support ECU 20 determines whether or not the calculated straight portion driving distance is a third threshold or less. If the straight portion driving distance is the third threshold or less (YES), the side support ECU 20 proceeds to Step S 27 . This example corresponds to a case where, the vehicle is driven on the current curve C 2 , after the vehicle, which was in the standby state ST 2 on the straight portion, was driven for the straight portion driving distance being the third threshold or less. On the other hand, if the straight portion driving distance is larger than the third threshold (NO), the side support ECU 20 terminates the curve driving program.

In Step S 27 , the side support ECU 20 sets the control state to the executed state ST 3 . Then, when the vehicle is driven on the straight portion between the curves, each of the right and left side support portions 16 and 17 are retained to a supporting position by each of the motors 26 and 27 . Hereinafter, “retaining the supporting position” indicates that the right and left side support portions 16 and 17 are retained to the supporting positions when the vehicle is driven on the straight portion between the curves. At this point, each the right and left side supporting portions 16 and 17 is retained to a maximum supporting position during the executed state ST 3 . Specifically, the right and left side support portions 16 and 17 are controlled so as to be opened/closed on the basis of a lateral acceleration detected by the lateral acceleration sensor 23 by following a program (not illustrated). Then, on the basis of the curve driving program and a straight portion running program, which will be explained later, when the control state is set to the executed state ST 3 , the right and left side support portions 16 and 17 are operated in a direction where the control level increases. As a result, each of the right and left side support portions 16 and 17 is retained to the maximum supporting position during the executed state ST 3 . After the execution in Step S 27 the curve driving program is terminated. On the curve driving program and the straight portion running program, during the unexecuted state ST 1 and the standby state ST 2 , the right and left side support portions 16 and 17 are not retained to the supporting positions and are controlled so as to be opened/closed on the basis of the lateral acceleration detected by the lateral acceleration sensor 23 by following a program (not illustrated).

In Step S 3 of the flowchart illustrated in FIG. 6 , the straight portion running program, which is indicated by the flowchart illustrated in FIG. 8 , is executed. At this point, the point P 5 is a current position, the curve C 2 is a previous curve, the ending point P 4 is an ending point of the previous curve, a distance between the ending point P 4 of the previous curve C 2 and the current position P 5 , or a distance between the starting point of the standby state ST 2 and the current position P 5 is a straight portion driving distance. Once the straight portion running program is executed, the side support ECU 20 checks a current control state in Step S 30 . If the current control state is set to the unexecuted state ST 1 , the straight portion running program is terminated. If the current control state is set to the standby state ST 2 , the side support ECU 20 proceeds to Step S 31 . If the current control state is set to the executed state ST 3 , the side support ECU 20 proceeds to Step S 36 .

In Step S 31 , the side support ECU 20 calculates a distance between the ending point P 4 of the previous curve C 2 and the current position P 5 during the standby state ST 2 . Then, the side support ECU 20 proceeds to Step S 32 . In Step 32 , the side support ECU 20 determines whether or not the calculated straight portion driving distance is larger than the second threshold. If the straight portion driving distance is larger than the second threshold (YES), the side support ECU 20 proceeds to Step S 35 . This example corresponds to a case where the control state is set to the standby state ST 2 while the vehicle was driven on the previous curve C 2 , and the straight portion driving distance between the ending point P 4 of the previous curve C 2 and the current position P 5 is larger than the second threshold. On the other hand, if the straight portion driving distance is the second threshold or less (NO), the side support ECU 20 proceeds to Step S 33 .

In Step S 33 , the side support ECU 20 calculates the straight portion driving distance between the starting point of the standby state ST 2 and the current position P 5 . Then, the side support ECU 20 proceeds to Step S 34 . In Step S 34 , the side support ECU 20 determines whether or not the straight portion driving distance is larger than the third threshold. If the straight portion driving distance is larger than the third threshold (YES), the side support ECU 20 proceeds to Step S 35 . This example corresponds to a case where the control state is set to the standby state ST 2 while the vehicle is driven on the straight portion, and the straight portion driving distance between the starting point of the standby state ST 2 and the current position P 5 is larger than the third threshold. On the other hand, if the straight portion driving distance is the third threshold or less (NO), the straight portion running program is terminated.

In Step S 35 , the side support ECU 20 sets the control state to the unexecuted state ST 1 and terminates the straight portion running program

In Step S 36 , the side support ECU 20 calculates the straight portion driving distance between the ending point P 4 of the previous curve C 2 and the current position P 5 during the executed state ST 3 . Then the side support ECU 20 proceeds to Step S 37 . In Step S 37 , the side support ECU 26 determines whether or not the straight portion driving distance is larger than the fourth threshold. If the straight portion driving distance is larger than the forth threshold (YES), the side support ECU 20 proceeds to Step S 38 . This example corresponds to a case where the control state is set to the executed state ST 3 while the vehicle was driven on the previous curve C 2 , and the straight portion driving distance between the ending point P 4 of the previous curve C 2 and the current position P 5 is larger than the fourth threshold. On the other hand, if the straight portion driving distance is the fourth threshold or less (NO), the straight portion running program is terminated. This example corresponds to a case where the control state has been maintained to the executed state ST 3 , and each of the right and left side support portions 16 and 17 is retained to the supporting position.

In Step S 38 , the side support ECU 20 sets the control state to the standby state ST 2 , and the right and left side support portions 16 and 17 , which has been retained to the supporting position, is released, and then the straight portion running program is terminated. Steps S 22 , S 23 , S 24 , S 26 , S 27 , S 32 , S 34 , S 35 , S 37 and S 38 serve as a control state determining means.

According to the seat apparatus of the first embodiment, in Steps S 24 , S 26 and S 27 , the control state is set to the executed state ST 3 on the basis of the distance between the previous curve C 1 and the current curve C 2 or the distance between the starting point of the standby state ST 2 and the starting point P 3 of the current curve C 2 , and then each of the side support portions 16 and 17 is retained to the supporting position by means of each motor 26 and 27 .

Thus, even when the vehicle speed is changed, during the executed state ST 3 , the side support portions 16 and 17 are surely retained to the supporting positions respectively.

Accordingly, when the vehicle is driven on the continuous curves, according to the seat apparatus in the first embodiment the side support portions 16 and 17 are stably controlled.

Further, in the first embodiment, because the control state is set to the unexecuted state ST 1 , the standby state ST 2 or the executed state ST 3 , even when the control state is set to the standby state ST 2 when the vehicle is driven on a long straight portion exists between the continuous curves, the controls states may be rapidly changed to the executed state ST 3 on the starting point of the next curve, as a result, the side support portions 16 and 17 are rapidly retained to supporting positions. According to the seat apparatus, the side support ECU 20 easily determines whether or not the vehicle is driven on the curve on the basis of a lateral acceleration detected by the lateral acceleration sensor 23 . Instead of the lateral acceleration sensor 23 , the curve may be detected on the basis of a lateral acceleration calculated by use of a steering angle detected by the steering angle sensor 24 and a vehicle speed detected by the vehicle speed sensor 22 .

FIGS. 9A , 9 B and 9 C illustrates an example when the side support control program is executed. Specifically, FIG. 9A illustrates a graph G 1 indicating a relation between the vehicle running distance and the lateral acceleration, FIG. 9B illustrates graphs G 2 and G 3 each indicating a relation between the vehicle running distance and the control state, and FIG. 9C illustrates a graph G 4 indicating a relation between the vehicle running distance and the control level. The control level includes five levels from level 0 to level 4 . In FIGS. 9A , 9 B and 9 C, each of C 10 through C 14 indicates a curve (curves C 10 , C 11 , C 12 , C 13 and C 14 ), and P 10 indicates a starting point of the curve C 10 , P 12 indicates a starting point of the curve C 11 , P 14 indicates a starting point of the curve C 12 , P 17 indicates a starting point of the curve C 13 , and P 19 indicates a starting point of the curve C 14 . Further, P 11 indicates an ending point of the curve C 10 , P 13 indicates an ending point of the curve C 11 , P 15 indicates an ending point of the curve C 12 , P 18 indicates an ending point of the curve C 13 , and P 20 indicates an ending point of the curve C 14 . Furthermore, P 0 indicates a point where the vehicle starts moving, and when the vehicle is positioned at the point P 0 , the control state is in the unexecuted state ST 1 . The first criterial number is set to “1”, the second criterial number is also set to “1”, the first threshold is set to 150 m, the second threshold is set to 180 m, the third threshold is set to 150 m, and the fourth threshold is set to 150 m. Further, a straight portion L 10 exists between the ending point P 11 and the staring point P 12 , a straight portion L 11 exists between the ending point P 13 and the starting point P 14 , a straight portion L 12 exists between the ending point P 15 and a point P 16 , a straight portion L 13 exists between the point P 16 and the starting point P 17 , a straight portion L 14 exists between the ending point P 18 and the starting point P 19 , a straight portion L 15 exists between the ending point P 20 and a point P 21 , and a straight portion L 16 exists between the point P 21 and a point P 22 . Furthermore, a distance of the straight portion L 10 is set to 120 m, a distance of the straight portion L 11 is set to 160 m, a distance of the straight portion L 12 is set to 170 m, a distance of the straight portion L 13 is set to 130 m, a distance of the straight portion L 14 is set to 130 m, a distance of the straight portion L 15 is set to 150 m and a distance of the straight portion L 16 is set to 150 m.

When the vehicle moving from the point P 0 is driven on the curve C 10 , because the distance between curves does not exist, the control state is set to the unexecuted state ST 1 . As indicated by the graph G 4 , while the vehicle is driven, the right and left side support portions 16 and 17 are controlled so as to be opened/closed on the basis of the lateral acceleration detected by the lateral acceleration sensor 23 following a program (not shown). While the vehicle is driven on the curve C 11 , the side support ECU 20 determines in Step S 22 that the distance between curves (120 m), which is the distance of the straight portion L 10 , is less than the first threshold (150 m). Then, the control state is set to the standby state ST 2 in Step S 23 .

While the vehicle is driven on the curve C 12 , the side support ECU 20 determines in Step S 24 that the distance between curves (160 m), which is the distance of the straight portion L 11 , is less than the second threshold (180 m). Then, the control state is set to the executed state ST 3 in Step S 27 . Then, on the straight portion L 12 , each of the right and left side support portions 16 and 17 is retained to the supporting position at a level illustrated in the graph G 4 . Thus, because the second threshold (180 m) is set to be larger than the first threshold (150 m), the control state is changed from the standby state ST 2 to the executed state ST 3 more smoothly than the case where the control state is changed from the unexecuted state ST 1 to the standby state ST 2 , and the continuous curves are surely detected.

When the vehicle reaches the point P 16 , the side support ECU 20 determines in Step S 37 that the straight portion driving distance (170 m), which is the distance between the ending point P 15 of the previous curve C 12 and the current position P 16 , is larger than the fourth threshold (150 m). Then, the control state is set to the standby state ST 2 in Step S 38 . Then, as indicated by the graph G 4 , each of the right and left side support portions 16 and 17 , which has been retained to the supporting position, is released.

while the vehicle is driven on the curve C 13 , the side support ECU 20 determines in Step S 26 that the straight portion driving distance (130 m), which is the distance between the starting point P 16 of the standby state ST 2 and the starting point P 17 of the curve C 13 , is less than the third threshold (150 m). Then, the control state is set to the executed state ST 3 in Step S 27 . On the straight portion L 14 , each of the right and left side support portion 16 and 17 is retained to the supporting position at a level indicated by the graph G 4 . The dashed line in the graph G 3 indicates a control state, which is set only to the unexecuted state ST 1 or the executed state ST 3 , not to the standby state ST 2 . In this case, if the side support ECU 20 detects that the vehicle has passed two continuous curves, the control state being the unexecuted state ST 1 is changed to the executed state ST 3 . When the controls state is not set to the standby state ST 2 as indicated in the graph G 3 , because the control state is changed to the executed state ST 3 only when the vehicle reaches the starting point P 19 of the curve C 14 , the right and left side support portions 16 and 17 are not retained to the supporting position on the straight portion L 14 . On the other hand, according to the seat apparatus in the embodiment, because the control state is set to the unexecuted state ST 1 , the standby state ST 2 or the executed state ST 3 , in case that the straight portions L 12 and L 13 , whose distances are relatively long, exist in the continuous curves, the control state is set to the standby state ST 2 on the straight portion L 12 , and then the control state is changed to the executed state ST 3 at the star point P 17 of the curve C 13 . Thus, as indicated by the graph G 4 , each of the right and left side support portions 16 and 17 is rapidly retained to the supporting position when the vehicle is driven on the straight portion L 14 .

When the vehicle is driven on the curve C 14 , the side support ECU 20 proceeds to Step S 21 and then proceeds to Step S 27 . In Steps S 21 and S 27 , the control state is maintained to the executed state ST 3 . Then, when vehicle is driven on the straight portion L 15 , each of the right and left side support portions 16 and 17 is retained to the supporting position at the level indicated by the graph G 4 . After the vehicle passes the point P 21 , the side support ECU 20 determines in Step 37 that the straight portion driving distance (150 m), which is a distance of the straight portion L 15 between the ending point P 20 of the previous curve C 14 and the point P 21 , is larger than the fourth threshold (150 m). Then, the control state is set to the standby state ST 2 in Step S 38 . Then, as illustrated in the graph G 4 , each of the right and left side support portions 16 and 17 , which has been retained to the supporting position, is released.

After the vehicle passes the point P 22 , the side support ECU 20 determines in Step 34 that the straight portion driving distance (150 m), which is a distance of the straight portion L 16 between the ending point P 21 of the standby state ST 2 and the point P 22 , is larger than the third threshold (150 m). In Step S 35 , the control state is set to the unexecuted state ST 1 .

Next, a seat apparatus in a second embodiment will be explained. In the same manner as the first embodiment, the seat apparatus in the second embodiment is operated by executing the side support control program explained in the drawings illustrated in FIGS. 1 through 8 . Specifically, when the program indicated in FIG. 6 is executed, before the side support ECU 20 executes the process in Step S 1 , a control forcible termination program, which is indicated in a flowchart in FIG. 10 , is executed.

In Step S 40 of the control forcible termination program, the side support ECU 20 checks whether or not the control state is set to the unexecuted state ST 1 . If the control state is the unexecuted state ST 1 (YES), the side support ECU 20 proceeds to Step S 41 . If the control state is the standby state ST 2 or the executed state ST 3 (NO), the side support ECU 20 proceeds to Step S 44 .

In Step S 41 , the side support ECU 20 checks whether or not the vehicle is driven at the vehicle speed being lower than 40 km per hour. If the vehicle speed is lower than 40 km per hour (YES), the side support ECU 20 proceeds to Step S 42 . If the vehicle speed is equal to or more than 40 km per hour (NO), the side support ECU 20 proceeds to Step S 43 . In this case, the vehicle speed (40 an per hour) is referred to as a first speed.

In Step S 42 , the side support ECU 20 stops to supply electric power to the motors 26 and 27 so that the controls of the side support portions 16 and 17 are forcibly stopped. Then, the side support ECU 20 terminates the control forcible termination program.

In Step S 43 , the side support ECU 20 permits to supply the electric power to the motors 26 and 27 so that the operations of the side support portions 16 and 17 are permitted. Then the side support ECU 20 terminates the control forcible termination program.

In Step S 44 , the side support ECU 20 checks whether or not the vehicle speed is lower than 30 km per hour. If the vehicle speed is lower than 30 km per hour (YES), the side support ECU proceeds to Step S 42 . If the vehicle speed is equal to or more than 30 km per hour (NO), the side support ECU proceeds to Step S 42 . In this case, the vehicle speed (30 km per hour) is referred to as a second speed.

According to the seat apparatus in the second embodiment, in the unexecuted state ST 1 , when the vehicle speed is lower than 40 km per hour, the controls of the side support portions 16 and 17 are stopped. Thus, when the vehicle is driving on a normal road, unnecessary controls to the side support portions 16 and 17 are forcibly stopped. Further, in the standby state. ST 2 and the executed state ST 3 , the controls of the side support portions 16 and 17 are forcibly terminated only when the vehicle is driven at 30 km per hour or lower. Thus, unless the vehicle is driven on, for example, a hairpin curve provided within the continuous curves at lower than the vehicle speed 30 km per hour, each of the side support portions 16 and 17 are retained to the supporting position. The seat apparatus in the second embodiment provides functions and effects that is identical to the seat apparatus in the first embodiment.

According to the seat apparatus, in the executed state, even when the vehicle speed has changed, the side support portion ( 16 / 17 ) is certainly retained to the supporting position. Thus, the supporting operation of the side support portion ( 16 / 17 ) is stably executed when the vehicle is driven on the continuous curves. Further, because the control state is set to the unexecuted state, the standby state or the executed state, when the vehicle is driven on the long straight proportion between the curves and the control state is set to the standby state, the control state is rapidly changed to the executed state at the starting point of the next curve. Thus, on the straight portion between the curves, the side support portion ( 16 / 17 ) is rapidly retained to the supporting position.

Further, the second threshold is set to be larger than the first threshold.

According to the seat apparatus, because the second threshold is larger than the first threshold, the control state is rapidly changed from the standby state to the executed state than the control state being the unexecuted state is changed to the standby state, and thus, the continuous curves are certainly detected.

Furthermore, in the unexecuted state, the driving means ( 26 / 27 ) forcibly stops the operation of the side support portion ( 16 / 17 ) when the vehicle speed is lower than a first speed.

According to the seat apparatus, when the vehicle is driven on a normal road, an unnecessary control of the side support portion ( 16 / 17 ) can be stopped.

Further, in the standby state and the executed state, the driving means ( 26 / 27 ) forcibly stops the operation of the side support portion ( 16 / 17 ) when the vehicle speed is lower than a second speed, which is set to be lower than the first speed.

According to the seat apparatus, unless the vehicle is driven on, for example, a hairpin curve provided within the continuous curves at lower than the second speed, the side support portion ( 16 / 17 ) is retained to the supporting position.

Further, the sensor is a lateral acceleration sensor ( 23 ) for detecting acceleration generated at the vehicle in a lateral direction thereof.

According to the seat apparatus, using the lateral acceleration sensor ( 23 ), a curve is easily detected.

Further, the sensor includes a steering angle sensor ( 24 ) and a vehicle speed sensor ( 22 ).

According to the seat apparatus, using the steering angle sensor ( 24 ) and the vehicle speed sensor ( 22 ), a curve can also be detected.

The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the sprit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.