JP2019206954A - Air compressor - Google Patents

Abstract

To prevent mixing of lubricating oil into discharged air without remodeling a crank mechanism.SOLUTION: An air compressor is provided that comprises: a crank case 11 in which lubricating oil is housed; a crank shaft 12 supported in the crank case 11; a cylinder 10 provided in the crank case 11; a piston 20 fitted into a liner 17 of the cylinder 10 in a freely reciprocatable manner and reciprocated by the crank shaft 12; a cylinder head 30 provided at a side opposite to the crank case 11, of the cylinder 10; and a suction valve 37 and a discharge valve 39 provided in the cylinder head 30, In the air compressor, a cylinder hole 25 is provided in the piston 20 in an embedded manner, a piston pole 41 is provided in a projected manner at a position opposed to the cylinder hole 25, of the cylinder head 30, the piston pole 41 is slidably fitted into the cylinder hole 25, and a communication passage 45 for communicating the inside and outside of a clearance 44 formed between an outer circumferential surface of the piston pole 41 and an inner circumferential surface of the liner 17 is provided in the liner.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reciprocating air compressor, and more particularly, to a technique for improving so that lubricating oil (oil) does not enter into discharge air from an air compressor.

In a conventional reciprocating type air compressor of this type, a lubricating oil is supplied to a bearing portion of a crankshaft, a connecting portion with a connecting rod, a sliding surface between a piston and a cylinder, etc., with a crankcase as a lubrication chamber. It is configured as follows.
However, in this lubricating structure, it is unavoidable that the lubricating oil goes up to the compression chamber, so that the lubricating oil is mixed into the discharge air, contaminates the filter of the air dryer in the rear system, and further the air dryer. Since the air exhausted from the outside also contains oil, it adversely affects the surrounding environment.
Therefore, in order to prevent the lubricant from entering the discharge air, a partition plate is provided between the crankcase and the cylinder, and an oil seal is provided between the partition plate and the connecting rod, so that There has been proposed an air compressor that prevents the intrusion of lubricating oil into a compression chamber formed in the chamber (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-103245

  However, the above-described air compressor in Patent Document 1 has a problem in that significant modification of the crank mechanism is inevitable in order to reduce the lateral load applied to the oil seal.

  An object of the present invention is to provide an air compressor that can prevent the lubricating oil from being mixed into the discharge air without modifying the crank mechanism.

Typical means for solving the above-described problems are as follows.
A crankcase containing lubricating oil, a crankshaft supported in the crankcase, a cylinder provided in the crankcase, and a reciprocating motion fitted in a liner of the cylinder and reciprocating by the crankshaft. An air compressor comprising: a piston to be operated; a cylinder head disposed on a side of the cylinder opposite to the crankcase; and a suction valve and a discharge valve provided on the cylinder head,
A cylinder hole is provided in the piston, a piston column is provided at a position facing the cylinder hole of the cylinder head, and the piston column is slidably fitted into the cylinder hole, The liner is provided with a communication path that communicates the inside and outside of the gap formed between the outer peripheral surface of the column and the inner peripheral surface of the liner.
An air compressor characterized by that.

  According to the present invention, it is possible to prevent the lubricating oil from being mixed into the discharge air without modifying the crank mechanism of the air compressor.

It is a longitudinal cross-sectional view which shows the intake end state of the air compressor which is 1st embodiment of this invention. It is a longitudinal cross-sectional view which shows the exhaustion completion state of the air compressor which is 1st embodiment of this invention. It is a longitudinal cross-sectional view which shows the completion | finish state of intake of the air compressor which is 2nd embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 and 2 show a first embodiment.
In this embodiment, the air compressor according to the present invention is configured to be mounted on a vehicle.
The air compressor 1 according to the present embodiment includes a cylinder 10, a piston 20 disposed in the cylinder 10 so as to be capable of reciprocating, and a cylinder head 30 disposed on an upper portion of the cylinder 10.
A crankcase 11 is formed at one end (hereinafter referred to as a lower end) of the cylinder 10, and a crankshaft 12 is rotatably supported in the crankcase 11 by a pair of bearings 13 and 13. A lower end portion of a connecting rod 14 is rotatably connected to an intermediate portion of the crankshaft 12, and a piston pin 15 of a piston 20 is rotatably connected to an upper end portion of the connecting rod 14.
A predetermined amount of lubricating oil is supplied and stored in the crankcase 11 from an oil supply port (not shown), and the bearings 13 and 13 of the crankshaft 12, the connecting portion between the crankshaft 12 and the connecting rod 14, and the connecting are connected. The connecting portion between the rod 14 and the piston pin 15 is oil lubricated.
One end of the crankshaft 12 protrudes outside the crankcase 11, and a connecting portion 16 is formed at the protruding end. The crankshaft 12 is rotationally driven by connecting a rotating shaft (not shown) on the engine side to the connecting portion 16 via a key, for example.

  A liner 17 is formed in the upper part of the cylinder 10 in a cylindrical shape, and a piston 20 is slidably fitted into the liner 17. An oil seal 18 is provided on the inner peripheral surface of the intermediate portion of the liner 17, and the inner peripheral surface of the oil seal 18 is in sliding contact with the outer peripheral surface of the upper end portion of the piston 20. An oil ring 19 is provided on the outer peripheral surface of the lower end portion of the piston 20, and the outer peripheral surface of the oil ring 19 is in sliding contact with the inner peripheral surface of the lower end portion of the liner 17.

A pin hole 21 is formed in the lower end portion of the piston 20 so as to be orthogonal to the connecting rod 14, and the piston pin 15 is fitted into the pin hole 21 and is prevented from coming off by a pair of stopper rings 22, 22. The piston pin 15 is formed in a cylindrical shape, and both ends of the pin hole 21 and the hollow portion of the piston pin 15 communicate with the liner 17.
A connecting portion of a connecting rod 14 is rotatably fitted to the piston pin 15. The contact surface between the pin hole 21 and the piston pin 15 and the contact surface between the piston pin 15 and the connecting rod 14 are lubricated by lubricating oil supplied from an oil supply port (not shown) of the crankcase 11. Lubricating oil is also supplied to the sliding surface between the liner 17 and the piston 20 from the crankcase 11 and from the pin hole 21.

The cylinder head 30 is placed on the upper end opening of the cylinder 10 and positioned by an indicia coupling portion 40, and is fastened by fastening means (not shown) such as a bolt.
A suction path 31 and a discharge path 32 are respectively opened in the cylinder head 30. The suction path 31 is connected to an air cleaner via an engine intake pipe, and the discharge path 32 is connected to a reservoir via a check valve and an air dryer.
A valve plate (valve plate) 33 and a suction valve reed valve 34 are overlapped on the lower end surface of the cylinder head 30 and fastened by fastening means (not shown) such as bolts. A suction port 36 is opened at a position facing the suction passage 31 of the valve plate 33, and the suction port 36 is opened and closed by a suction valve 37 formed in the reed valve 34. A discharge port 38 is opened at a position facing the discharge path 32 of the valve plate 33, and the discharge port 38 is opened and closed by a discharge valve 39.

A cylinder hole 25 is recessed in a cylindrical hole shape on the upper end surface of the piston 20, and a piston column 41 protrudes in a cylindrical shape at a position facing the cylinder hole 25 of the cylinder head 30. The piston column 41 is slidably fitted into the cylinder hole 25 and relatively reciprocates in the cylinder hole 25 as the piston 20 reciprocates. Since the compression action of air is performed by the reciprocating motion of the piston column 41 in the cylinder hole 25, the cylinder hole 25 and the piston column 41 constitute a compression chamber 42.
The valve plate 33 is disposed at the lower end of the piston column 41 and has the same diameter, and a pressure ring 43 is fixed to the outer periphery thereof. The outer peripheral surface of the pressure ring 43 is in sliding contact with the inner peripheral surface of the upper end portion of the cylinder hole 25.

A gap 44 having a width corresponding to the thickness of the side wall of the cylinder hole 25 is formed between the outer peripheral surface of the piston column 41 and the inner peripheral surface of the upper end portion of the liner 17. Reciprocates following the reciprocating motion of the piston 20 relative to the liner 17, that is, relative to the cylinder hole 25 of the piston column 41.
A communication passage 45 is formed at the upper end of the liner 17 so as to communicate between the inside and outside of the gap 44, and the communication passage 45 allows a change in volume of the gap 44 due to reciprocation of the side wall of the cylinder hole 25. A filter 46 that allows only air flow is installed in the communication path 45. That is, the filter 46 prevents entry of dust and water droplets from the engine room into the gap 44 and allows the air to enter and exit the gap 44.

  Next, the operation of the air compressor 1 will be described.

When the crankshaft 12 is rotationally driven by an engine or the like, the piston 20 reciprocates in the liner 17 via the connecting rod 14. When the piston 20 reciprocates in the liner 17, the change in volume of the gap 44 is allowed by the communication path 45, so that the piston column 41 protruding from the cylinder head 30 is inside the cylinder hole 25 submerged in the piston 20. Is reciprocated relatively.
A compression action in the compression chamber 42 is performed by the action of the suction valve 37 and the discharge valve 39 accompanying the reciprocating motion in the cylinder hole 25 of the piston column 41, and the discharge air compressed to a predetermined pressure is discharged from the discharge port 38. Is done.
Incidentally, the pressure ring 43 prevents the pressure in the compression chamber 42 from leaking.
The filter 46 prevents dust and water droplets from entering the gap 44 from the engine room.

  During the compression operation of the air compressor 1, oil lubrication is performed on the sliding surfaces of the bearings 13 and 13 of the crankshaft 12 and the liner 17 and the piston 20 by the splashing action of the lubricating oil accompanying the rotation of the crankshaft 12. Further, the contact surfaces of the pin hole 21, the piston pin 15 and the connecting rod 14 are lubricated by lubricating oil supplied from an oil supply port (not shown) provided in the crankcase 11. Such oil lubrication prevents the occurrence of troubles such as seizure during operation of the air compressor 1.

At this time, since the compression chamber 42 formed by the cylinder hole 25 and the piston column 41 is isolated from the crankcase 11 through the gap 44 between the liner portion 17 and the piston column 41, the lubricating oil and the crank A so-called oil mist generated in the case 11 is prevented from entering the compression chamber 42.
Therefore, mixing of lubricating oil and oil mist into the discharge air discharged from the discharge port 38 is suppressed.
Incidentally, the lubricating oil adhering to the outer peripheral surface of the piston 20 is scraped off by the oil seal 18. The lubricating oil scraped off returns to the crankcase 11 through the clearance between the liner 17 and the piston 20.

  According to this embodiment, the following effects can be obtained.

(1) During the compression operation of the air compressor 1, the sliding surfaces of the bearings 13 and 13 of the crankshaft 12, the liner 17 and the piston 20 and the contact surfaces of the pin hole 21, the piston pin 15 and the connecting rod 14 are oil. Since lubrication is performed, the occurrence of seizure or the like during the operation of the air compressor 1 can be prevented.

(2) Since the compression chamber 42 formed by the cylinder hole 25 and the piston column 41 is isolated from the crankcase 11 through the gap 44 between the liner portion 17 and the piston column 41, the lubricating oil and the crank It is possible to prevent so-called oil mist generated in the case 11 from entering the compression chamber 42.

(3) By preventing the so-called oil mist generated in the lubricating oil and the crankcase 11 from entering the compression chamber 42, the lubricating oil and the oil mist are mixed into the discharge air discharged from the discharge port 38. In addition, it is possible to prevent carbonization due to the contact of the lubricating oil or oil mist with high-temperature compressed air.

(4) By connecting the cylinder head 30 to the liner 17 by stamping, the clearance between the cylinder hole 25 and the piston column 41 can be managed easily and appropriately.

(5) By providing the pressure ring 43 in sliding contact with the inner peripheral surface of the cylinder hole 25 on the outer peripheral surface of the piston 20, leakage of pressure in the compression chamber 42 can be prevented.

(6) By reducing the lubricating oil scraped off by the oil seal 18 into the crankcase 11 through the clearance between the liner 17 and the piston 20, it is possible to prevent the lubricating oil from decreasing.

(7) By eliminating the piston ring on the outer peripheral surface of the piston 20, it is possible to reduce the factor of scooping up the lubricating oil, so that the penetration of the lubricating oil and oil mist into the compression chamber 42 can be further suppressed. .

(8) By installing the filter 46 in the communication path 45, it is possible to prevent dust and water droplets from entering the gap 44 from the engine room.

(9) Since the oil lubrication part and the compression chamber are separated, the compression chamber is freed from the design problem of the sliding structure between the liner and the piston, and the sliding part in the compression chamber (the cylinder hole and the piston column) The degree of freedom of the oil-less design of the opposed surface of the resin can be increased, and the use of resin parts such as liners, pistons, and cylinder heads, and the expansion of options for the coating material of the sliding surface can be promoted.

(10) Since it is not necessary to provide an oil seal between the partition plate between the crankcase and the cylinder and between the partition plate and the connecting rod, modification of the crank mechanism of the air compressor can be avoided.

FIG. 3 shows a second embodiment of the present invention.
This embodiment is different from the first embodiment in that a drain 51 is opened at a position above the oil seal 18 in the liner 17 so as to communicate the inside and outside, and a drain device 52 is connected to the drain 51. The drain device 52 is provided with a discharge path 53 connecting the drain 51 and the inside of the crankcase 11, a buffer 54 interposed in the discharge path 53, and a direction switching valve 55.
The direction switching valve 55 is always closed, and is opened by a solenoid after a preset time has elapsed after the engine is stopped, and is closed by a solenoid when a preset time has elapsed after opening. While the discharge path 53 is closed by the direction switching valve 55, the lubricating oil is accumulated in the buffer 54, and when the direction switching valve 55 is opened, the lubricating oil is returned from the buffer 54 into the crankcase 11.
According to this embodiment, in addition to the effect of the first embodiment, it is possible to obtain an effect that the reduction of the lubricating oil can be further suppressed.

  In addition, this invention is not limited to the said embodiment, It cannot be overemphasized that it can change variously in the range which does not deviate from the summary.

  The drain path of the drain device is not limited to being connected to the crankcase, but may be connected to an oil supply pipe for circulating the lubricating oil.

  The direction control valve of the drain device is not limited to a solenoid type, but may be a pilot type or a manual type.

  The intake valve and the discharge valve are not limited to reed valves, and may be configured from disk valves or the like.

  In the above-described embodiment, the air compressor mounted on the vehicle has been described. However, the present invention is not limited to this and can be applied to all air compressors used for other purposes.

DESCRIPTION OF SYMBOLS 1 ... Air compressor, 10 ... Cylinder, 11 ... Crankcase, 12 ... Crankshaft, 13 ... Bearing, 14 ... Connecting rod, 15 ... Piston pin, 16 ... Connection part, 17 ... Liner part, 18 ... Oil seal, 19 ... Oil ring,
20 ... Piston, 21 ... Pin hole, 22 ... Stopper ring, 25 ... Cylinder hole,
30 ... Cylinder head, 31 ... Suction passage, 32 ... Discharge passage, 33 ... Valve plate (valve plate), 34 ... Reed valve for suction valve, 36 ... Suction port, 37 ... Suction valve, 38 ... Discharge port, 39 ... Discharge valve,
40 ... Indicating joint, 41 ... Piston column, 42 ... Compression chamber, 43 ... Pressure ring, 44 ... Gap, 45 ... Communication passage, 46 ... Filter,
51... Drain, 52... Drain device, 53.

Claims (5)

A crankcase containing lubricating oil, a crankshaft supported in the crankcase, a cylinder provided in the crankcase, and a reciprocating motion fitted in a liner of the cylinder and reciprocating by the crankshaft. An air compressor comprising: a piston to be operated; a cylinder head disposed on a side of the cylinder opposite to the crankcase; and a suction valve and a discharge valve provided on the cylinder head,
A cylinder hole is provided in the piston, a piston column is provided at a position facing the cylinder hole of the cylinder head, and the piston column is slidably fitted into the cylinder hole, The liner is provided with a communication path that communicates the inside and outside of the gap formed between the outer peripheral surface of the column and the inner peripheral surface of the liner.
An air compressor characterized by that. A filter that allows only air flow in the communication path is installed,
The air compressor according to claim 1. An oil seal is provided on the inner peripheral surface of the intermediate portion of the liner, and the inner peripheral surface of the oil seal is in sliding contact with the outer peripheral surface of the piston.
The air compressor according to claim 1 or 2, characterized in that. An oil ring is provided on the outer peripheral surface of the piston, and the outer peripheral surface of the oil ring is in sliding contact with the inner peripheral surface of the liner.
The air compressor according to claim 1, 2, or 3. The drain is opened to communicate with the liner inside and outside, and a drain device for returning the lubricating oil to the crankcase is connected to the drain.
The air compressor according to claim 1, 2, 3 or 4.

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