Air compressor

This application is based on and claims priority under 35 U.S.C. §119 with respect to Japanese Application No. 2000-017439 filed on Jan. 26, 2000, the entire content of which is incorporated herein by reference.

The present invention generally relates to an air compressor. More particularly, the present invention pertains to an air compressor of the air pressure type that is used in a vehicular height adjusting device.

A known air compressor is disclosed in, for example, Japanese Patent Laid-Open Publication No. Hei 9-250507 published on Sep. 22, 1997. This air compressor includes a cylinder head comprised of a housing and a cover plate. The housing forms the valve seats of a suction valve and a discharge valve, and accommodates the suction valve and the discharge valve. The cover plate closes an upper opening edge of the housing. The housing is fixed against the cylinder by a fixing member which engages the cover plate so as to touch an opening edge of the cylinder.

In the above-mentioned air compressor, it is necessary to exchange or use a different housing to change the structure of the suction valve, to change the opening-pressure of the discharge valve or to change the characteristic of the air compressor by tuning the diameters of the suction port of the suction valve and the discharge port of the discharge valve. However, from a cost standpoint, this is quite undesirable because the housing is generally the largest member amongst the various members forming the cylinder head and is relatively expensive.

In light of the foregoing, a need exists for an air compressor which allows various aspects of the compressor such as those mentioned above to be changed in a relatively cost-effective manner.

One aspect of the present invention involves an air compressor that includes a cylinder head accommodating a suction valve and a discharge valve, a cylinder having an open end closed by the cylinder head, a piston slidably positioned within the cylinder and forming a variable volume chamber with the cylinder head, and a driving device for driving the piston in a reciprocating manner. The cylinder head includes a plate forming a valve seat and a suction port of the suction valve, and a valve seat and a discharge port of the discharge valve. The cylinder head also includes a housing accommodating the suction valve, the discharge valve and the plate, with the plate being fixed against the cylinder by a fixing member so that the plate confronts the opening end of the cylinder.

This construction of the air compressor is quite advantageous from the standpoint of cost because the housing does not need to be exchanged to change the structure of the suction valve, to change the opening-pressure of the discharge valve or to change the characteristic of the air compressor by tuning the diameters of the suction port of the suction valve and the discharge port of the discharge valve. Rather, with the present invention, these changes can be accomplished by exchanging the plate which forms a much smaller and less expensive part of the cylinder head.

According to another aspect of the present invention, an air compressor includes a housing and a plate forming a cylinder head, with the plate being provided with a suction port forming part of a suction valve and a discharge port forming part of a discharge valve. A cylinder has an open end that is closed by the cylinder head. A first seal member is positioned to provide a seal between the plate and the housing while a second seal member is positioned to provide a seal between the plate and the cylinder. A fixing member fixes the cylinder head to the cylinder. A piston is slidably positioned in the cylinder and forms a variable volume chamber with the cylinder head, and a driving device is operatively connected to the piston to drive the piston in a reciprocating manner.

In accordance with another aspect of the invention, an air compressor includes a housing and a plate forming a cylinder head, with the plate being provided with a suction port and a suction valve seat, and being provided with a discharge port and a discharge valve seat. A suction valve member is accommodated on the plate and is positionable in engagement with the suction valve seat to close the suction port and is movable out of engagement with the suction valve seat to open the suction port. A discharge valve member is positioned within the cylinder head and is positionable in engagement with the discharge valve seat to close the discharge port and is movable out of engagement with the discharge valve seat to open the discharge port. A cylinder has an open end that is closed by the cylinder head and a fixing member fixes the cylinder head to the cylinder. A piston is slidably positioned in the cylinder and forms a variable volume chamber with the cylinder head. A driving device is operatively connected to the piston to move the piston within the cylinder.

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 drawing figures in which like reference numerals designate like elements and wherein:

FIG. 1 is a vertical cross-sectional view of an air compressor according to one embodiment of the present invention;

FIG. 2 is a top view of the air compressor shown in FIG. 1;

FIG. 3 is a vertical cross-sectional view of the cylinder head forming a part of the air compressor shown in FIG. 1;

FIG. 4 is a top view of the plate used in the cylinder head illustrated in FIG. 3;

FIG. 5 is a bottom view of the plate shown in FIG. 4;

FIG. 6 is a bottom view of the seal member used in the cylinder head illustrated in FIG. 3;

FIG. 7 is a bottom view of the housing accommodating the seal member depicted in FIG. 6;

FIG. 8 is a bottom view of the cylinder head used in the air compressor shown in FIG. 1;

FIG. 9 is a cross-section view of the cylinder head taken along the section line 9 — 9 of FIG. 8;

FIG. 10 is an enlarged view of the discharge valve of the cylinder head shown in FIG. 3;

FIG. 11 is a cross-section view of the cylinder head according to a second embodiment of the present invention;

FIG. 12 is top view of a second embodiment of a plate used in the cylinder head;

FIG. 13 is bottom view of the plate shown in FIG. 12; and

FIG. 14 is a cross-sectional view of the plate according to the second embodiment of the present invention.

Referring initially to FIGS. 1-3, the air compressor according to the present invention includes a cylinder head 11 in which is disposed a suction valve 16 , a discharge valve 17 and a solenoid 18 which releases the compressed air, a cylinder 12 which has an opening edge or open end closed by the cylinder head 11 , a piston 14 which is slidably inserted in the cylinder 12 and forms a variable volume chamber 13 with the cylinder head 11 , and a driving device 15 which drives the piston 14 in a reciprocating manner.

The driving device 15 includes a motor 15 A, a rotating member 15 B operatively associated with the motor 15 A, and a connecting rod 15 C. The upper edge or end of the connecting rod 15 C is connected with the piston 14 and the bottom edge or end of the connecting rod 15 C is connected with the rotating member 15 B at a point radially spaced from the central axis of the rotating member 15 B.

As best seen in FIG. 3, the cylinder head 11 includes a plate 11 A, a housing 11 B which accommodates the plate 11 A, the suction valve 16 , the discharge valve 17 , and a seal member 11 C fixed between the plate 11 A and the housing 11 B. The plate 11 A is fixed against the cylinder 12 by a fixing member which may be in the form of a plurality of removable bolts 19 A (e.g., three bolts) which engage the housing of the motor 15 A while penetrating an outer flange of the housing 11 B. The plate 11 A thus confronts the opening edge of the cylinder 12 . It is to be understood that the number of bolts 19 A may be varied and is not restricted to the three illustrated in FIG. 2 .

As shown in FIG. 4 and FIG. 5, the plate 11 A is generally circular or disk-shaped and is preferably made of metal. The plate 11 A forms a valve seat 16 A and a suction port 16 B of the suction valve 16 as well as a valve seat 17 A and a discharge port 17 B of the discharge valve 17 . Two radially outwardly extending protrusions 11 A 1 are provided on the outer surface of the plate 11 A. In the illustrated embodiment, the protrusions 11 A 1 are positioned at diametrically opposite positions on the plate 11 A. In addition, the plate 11 A is provided with a ring-shaped groove 11 A 2 that receives a ring-shaped seal member 20 which confronts and contacts the upper edge of the cylinder 12 . The seal member 20 provides a seal between the plate 11 A and the cylinder 12 when the bolts 19 A are secured in place.

As shown in FIG. 3 and FIG. 6, the seal member 11 C is generally ring-shaped and is provided with two radially outwardly extending protrusions 11 C 1 on its outer surface. In the illustrated embodiment, the protrusions 11 C 1 are positioned at diametrically opposite positions on the seal member 11 C. The seal member 11 C forms a seal between the plate 11 A and the housing 11 B when the bolts 19 A are secured in place.

As shown in FIG. 7, the housing 11 B has a suction pipe 11 B 1 , a discharge pipe 11 B 2 , a chamber 11 B 3 communicating with the suction pipe 11 B 1 and the suction port 16 B, a chamber 11 B 4 communicating with the discharge pipe 11 B 2 and accommodating the discharge valve 17 , and a port 11 B 5 communicating with the chamber 11 B 4 for releasing the compressed air. This port 11 B 5 is selectively opened or closed by the solenoid 18 .

The housing 11 B also has two recesses 11 B 6 which receive and are engaged by the protrusions 11 C 1 of the seal member 11 C. The recesses 11 B 6 and the protrusions 11 C 1 thus form engaging portions that engage one another, with the engagement between the protrusions 11 C 1 and the recesses 11 B 6 fixing the circumferential position of the housing 11 B and the seal member 11 C relative to one another.

It is to be understood that the seal member 11 C may also be attached to the plate 11 A by baking the rubber material forming the seal member. In this case, the protrusions 11 C 1 on the seal member 11 C can be omitted.

FIG. 8 illustrates that the housing 11 B is provided with two recesses 11 B 7 which receive and are engaged by the protrusions 11 A 1 of the plate 11 A. The recesses 11 B 7 and the protrusions 11 A 1 thus form engaging portions that engage one another, with the engagement between the protrusions 11 A 1 and the recesses 11 B 7 fixing the circumferential position of the plate 11 A and the housing 11 B relative to one another.

As shown in FIGS. 8 and 9, the suction valve 16 includes a tongue-shaped suction valve member 16 C forming a leaf spring and a guide 16 E which restricts lifting of the valve 16 C. One end of the suction valve member 16 C and the guide 16 E are fixed on the plate 11 A by two pins 16 D. The suction valve member 16 C contacts the valve seat 16 A to close the suction port 16 B in the case of positive pressure in the variable volume chamber 13 and is detached from or moved out of contact with the valve seat 16 A to open the suction port 16 B in the case of negative pressure in the variable volume chamber 13 . In this way, the suction valve 16 is generally constructed as a reed valve.

Referring to FIG. 10, the discharge valve 17 includes a valve seat 17 A, a discharge valve member 17 C and a spring 17 D which is held between the valve 17 C and the housing 11 B to push the discharge valve member 17 C toward the valve seat 17 A. The discharge valve member 17 C contacts the valve seat 17 A to close the discharge port 17 B under the load or urging force of the spring 17 D and is detached or moved away from the valve seat 17 A to open the discharge port 17 B in the case of positive pressure in the variable volume chamber 13 . In this way, the discharge valve 17 is generally constructed as a poppet valve.

The operation of the air compressor 10 according to the present invention is the same as the operation of other known air compressors such as that described above. Thus, a detailed explanation of the operation of the air compressor is not included here as such operation is known to persons skilled in the art. In the air compressor 10 according to the present invention, the load of the spring 17 D changes depending on the height of the valve seat 17 A of the plate 11 A of the cylinder head 11 (i.e., the distance between the valve seat 17 A and the upper surface of the plate 11 A in FIG. 10 ). Therefore, it is only necessary to change or exchange the plate 11 A in order to change the opening-pressure of the discharge valve 17 , as well as the characteristics of the air compressor 10 by tuning the diameters of the suction port 16 B or the discharge port 17 B which are formed on the plate 11 A. From a cost perspective, it is much more desirable to exchange or change the plate 11 A than it is to exchange the housing 11 B because the plate 11 A is significantly smaller than the housing 11 B. Moreover, the housing 11 B can be made of resin. In this regard, the air compressor 10 of the present invention is favorable not only from the standpoint of cost but also from the standpoint of weight.

Referring to FIGS. 11-14, a suction valve 116 according to a second embodiment of the present invention includes a valve seat 116 A formed on a plate 111 A, a suction port 111 B formed on the plate 111 A, a valve 116 C, and a spring 116 E held between a retainer 116 D disposed on the valve 116 C and the plate 111 A. The plate 111 A possesses a cylindrical portion 111 A 3 accommodating the retainer 116 D and the spring 116 E. Also the plate 111 A is provided with a valve seat 117 A and a discharge port 117 B of the discharge valve, two radially outwardly directed protrusions 111 A 1 and a groove 111 A 2 . If the plate 111 A assembled with this suction valve 116 is formed so as to be compatible with the plate 11 A according to the first embodiment of the present invention described above, it is only necessary to exchange the plate, even when the structure of the suction port is changed. This is favorable from the standpoint of cost.

As mentioned above, the air compressor according to the present invention is considerably more favorable from the standpoint of cost as compared to other known constructions such as that described above because the housing which is the largest member forming the cylinder head does not need to be exchanged. Rather, only the plate needs to be exchanged in order to change the structure of the suction valve, to change the opening-pressure of the discharge valve or to change the characteristic of the air compressor by tuning the diameters of the suction port of the suction valve and the discharge port of the discharge valve.

The principles, preferred embodiments and modes 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 spirit 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.