JPH1193839A - Air compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air compressor capable of securing the durability of the junction of a crankshaft with a bearing section and a connecting rod with a lubricant and capable of blocking the mingling of the lubricant into the discharged air without being enlarged in size like a crosshead type one. SOLUTION: A piston 3 is reciprocated in a cylinder 2 in this reciprocating air compressor, a flexible diaphragm 23 is arranged between the piston 3 side and the cylinder 2 side, and the infiltration of a lubricant into a compression chamber formed above the piston 3 is blocked by the diaphragm 23. When the capacity of a void 28 formed between the diaphragm 23, piston 3 side, and cylinder 2 side is set not to be changed by the reciprocation of the piston 3, the load to the diaphragm 23 by the pulsating pressure based on the capacity change of the void 26 is avoided, and durability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating air compressor. More specifically, the present invention relates to an improved technique for improving lubricating oil not to be mixed into air discharged from the air compressor.

[0002]

2. Description of the Related Art In a reciprocating air compressor of this type, the lower part of a piston has conventionally been used as a lubrication chamber in a bearing portion of a crankshaft, a connecting portion between a connecting rod and a sliding surface between a piston and a cylinder. It is common to provide lubricating oil. However, in this lubrication structure, the lubricating oil is mixed into the discharge air due to the excessive supply of the lubricating oil or the wear of the piston ring, which may cause the operation of the air brake device or the like for the vehicle to which the discharge air is used. In some cases, it was troublesome. Therefore, various improved techniques have been disclosed to prevent lubricating oil from being mixed into the discharge air. For example, between the piston side and the cylinder side, a thin cylindrical member for partitioning is disposed in a state where one end is vertically movably fitted in a narrow groove formed on the piston side to prevent infiltration of lubricating oil. A porous ring is provided on a portion of a piston shaft of a crosshead type which is connected to a connecting rod via a crosshead and which is guided vertically so as to be able to block (JP-A-3-279681). (Japanese Unexamined Patent Publication No. 5-195856) and oil-less type (Japanese Utility Model Laid-Open No. 55-167584, Japanese Unexamined Utility Model Publication No.
No. 121482) is disclosed.

However, among the above-mentioned prior arts, those using a thin-walled cylindrical member for partitioning generate a pulse pressure by changing the volume of a space surrounded by the thin-walled cylindrical member, the piston and the cylinder by the vertical movement of the piston. There is a disadvantage that. Therefore, a communication hole is formed in the cylinder wall to open to the atmosphere side. However, there is a limit to the reduction of the pulse pressure by the communication hole, and it is technically difficult to reduce the pulse pressure to zero. In addition, the intrusion of dust and the like from the communication hole becomes a new problem. In addition, the crosshead type has a drawback that it is dimensionally large due to its mechanism. In the case of an oil-less type, it is practically possible to reduce the oil load on the sliding surface between the cylinder and the piston ring because the load is not so large. However, the connection between the crankshaft bearing and the connecting rod is required. However, there is a problem that it is difficult to secure the durability that can withstand the demands of the market because the oil-less method has a large load and a short life.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional technical circumstances, and supplies lubricating oil to a bearing portion of a crankshaft and a connecting portion to a connecting rod. It is an object of the present invention to provide an air compressor improved so that durability can be ensured and the lubricating oil can be prevented from being mixed into the discharge air without being dimensionally increased unlike the crosshead type. Things. It is another object of the present invention to reduce the pulse pressure derived from the reciprocation of the piston.

[0005]

According to the present invention, there is provided a reciprocating air compressor in which a piston reciprocates in a cylinder. Arranging a diaphragm having
A technical means is employed in which lubricating oil is prevented from entering the compression chamber formed above the piston by the diaphragm. Furthermore, by setting the volume of the gap formed between the diaphragm and the piston side and the cylinder side so as not to be changed by the reciprocating motion of the piston, the generation of the pulse pressure can be avoided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The diaphragm in the present invention is made of a thin rubber or oil-resistant, as long as it has appropriate flexibility and durability and can block the passage of lubricating oil. It is possible to use those formed from various materials, such as those made of cloth and synthetic thin films. Further, it is also possible to make it possible to flow only air by forming a communication hole at an appropriate portion of the diaphragm and mounting a filter capable of blocking the passage of lubricating oil at that portion.
Further, the diaphragm may be mounted at any position as long as it is disposed between the piston side and the cylinder side. The mounting portion on the piston side may be a portion of the piston itself or another member fixed to the piston as long as the portion operates integrally with the piston below the piston ring. The mounting portion on the cylinder side may be an appropriate portion on the cylinder side, and may be configured so as to be simultaneously sandwiched and mounted on a joint between the cylinder and the crankcase. In short, if it is necessary to prevent the lubricating oil from being mixed into the discharge air, and if it can effectively prevent the infiltration of the lubricating oil into the compression chamber formed above the piston, attach it to an appropriate part. Is possible. Further, the tension of the diaphragm is set in a slightly loosened state so that unnecessary force does not act on the diaphragm due to the reciprocating motion of the piston. In that case, if the volume of the gap formed between the diaphragm and the piston side and the cylinder side is set so as not to change due to the reciprocating motion of the piston, an unnecessary load on the diaphragm due to the operation of the piston can be avoided. Desirably, a slight change in volume can be absorbed by deformation of the diaphragm.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are longitudinal sectional views showing one embodiment of the present invention. FIG. 1 is an exhaust end state in which a piston is located at a top dead center, and FIG. 2 is an intake end state in which a piston is located at a bottom dead center. It shows the state. In FIG. 1, reference numeral 1 denotes an entire air compressor, which includes a cylinder 2, a piston 3 disposed reciprocally in the cylinder 2, and a cylinder head 4 disposed above the cylinder 2. , A crankshaft 6 disposed below the cylinder 2 and connected to the piston 3 via a connecting rod 5
Is constituted as a main element. The cylinder head 4 is provided with an intake valve 9 communicating with the intake port 8 and an exhaust valve 11 communicating with the exhaust port 10. An operation pin 12 for unloading is installed above the intake valve 9, and by supplying a signal pressure for unloading operation through a signal port 13, the intake valve 9 can be opened downward to unload. It is configured as follows.

As shown in FIG. 2, a compression chamber 14 is formed above the piston 3, and the exhaust valve 11 is opened by the compressed air pressure to discharge the compressed air from the exhaust port 10. I have. Further, the crankshaft 6 is rotatably supported by bearings 15 and 16 such as bearings installed on the crankcase 7, and via the connecting rod 5 disposed between the crankpin 17 and the piston pin 18. The piston 3 is configured to move up and down along the inner surface of the cylinder 2. Further, a predetermined amount of lubricating oil is stored in the crankcase 7, and the bearings 15 and 16 of the crankshaft 6 and the connection between the connecting rod 5 and the crankpin 17 are lubricated with oil. In the figure, reference numeral 19 denotes a connection portion of the crankshaft 6, and the connection portion
The air compressor 1 is driven by connecting, for example, a rotating shaft on the engine side via the zero. In the drawing, reference numeral 21 denotes a piston ring.

Next, specific technical means for preventing lubricating oil from being mixed into the discharge air, which is a feature of the present invention, will be described. As shown, in the present embodiment, the inner peripheral portion of a flexible diaphragm 23 is fixed via a support member 22 provided below the piston 3. That is, with the inner peripheral portion of the diaphragm 23 interposed between the support member 22 and a fixing member 25 which is installed to be able to be tightened via the tightening screw 24 with respect to the support member 22, the tightening screw 24 It is configured to be fastened and fixed. On the other hand, the outer peripheral portion of the diaphragm 23 is configured to be sandwiched and fixed between the cylinder 2 and the crankcase 7. In fixing the diaphragm 23, the volume of the gap 26 formed between the diaphragm 23 and the piston 3 side and the cylinder 2 side is different from the case of FIG. If the tension of the diaphragm 23 is set so that no change occurs between the case of FIG. 2 and the case of FIG.
Diaphragm 2 by pulse pressure induced by volume change of 6
An extra load on 3 can be avoided. Further, even when the volume of the gap 26 slightly changes due to the reciprocating motion of the piston 3, the diaphragm 23 has flexibility, so that it is possible to easily cope with the deformation by absorbing the deformation. Needless to say, the fixed portion of the diaphragm 23 can be changed to another portion. The point is that the diaphragm 23 may be any part that can prevent the lubricating oil in the crankcase 7 from entering the compression chamber 14.

When the crankshaft 6 is driven to rotate by an engine (not shown) or the like, the piston 3 reciprocates in the cylinder 2 via the connecting rod 5 so that the air is compressed. , The discharge air compressed to a predetermined pressure is discharged. During the operation of the air compressor 1, the bearings 15, 16 of the crankshaft 6 and the connection between the crankpin 17 and the connecting rod 5 are lubricated with lubricating oil. Movement to is blocked. Therefore, the infiltration of the lubricating oil into the compression chamber 14 formed above the piston 3 is prevented by the diaphragm 23
Thus, the lubricating oil is reliably prevented from being mixed into the discharge air discharged from the exhaust port 10. Although the sliding surface between the piston ring 21 and the cylinder 2 is in an oil-less state, the load acting therebetween is not so large, so that it is possible to sufficiently cope with it without using oil lubrication.

[0011]

According to the present invention, the following effects can be obtained. (1) Oil lubrication is performed on the bearing portion of the crankshaft and the connecting portion with the connecting rod, thereby ensuring durability and preventing lubricating oil from being mixed into the discharge air. (2) Since the infiltration of the lubricating oil into the compression chamber formed above the piston is prevented by using a flexible diaphragm, a large pulse pressure is generated by the reciprocation of the piston. Problems can be avoided. (3) If the volume of the gap surrounded by the diaphragm, the piston side and the cylinder side is set so as not to be changed by the reciprocating motion of the piston, an unnecessary load on the diaphragm based on the pulse pressure generated by the operation of the piston can be eliminated. It is possible to improve the durability of the diaphragm. (4) The size can be reduced as compared with the crosshead type.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view showing an exhausted state according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing an end state of intake air according to the embodiment.

[Description of Signs] 1. Air compressor, 2. Cylinder, 3. Piston,
4 ... Cylinder head, 5 ... Connecting rod, 6 ...
Crankshaft, 7 ... Crankcase, 8 ... Inlet,
9: intake valve, 10: exhaust port, 11: exhaust valve, 1
2 ... operating pin for unloading, 13 ... signal port, 14
… Compression chamber, 15, 16… bearing part, 17… crank pin,
18 ... piston pin, 19 ... connection part, 20 ... key for connection, 21 ... piston ring, 22 ... support member, 23 ... diaphragm, 24 ... fastening screw, 25 ... fixing member, 26 ...
Void

Claims (2)

[Claims] In a reciprocating air compressor in which a piston reciprocates in a cylinder, a flexible diaphragm is disposed between the piston and the cylinder, and the diaphragm is provided above the piston by the diaphragm. An air compressor wherein lubricating oil is prevented from entering the formed compression chamber. 2. The air compressor according to claim 1, wherein a volume of a gap formed between the diaphragm and the piston and the cylinder is not changed by reciprocation of the piston.