JP3064274B2 - Air compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air compressor used for an air pipe for supplying compressed air to an air brake, an air suspension, an automatic door and the like of a vehicle.

[0002]

2. Description of the Related Art In such an air piping system, generally,
Compressed air is supplied to an air tank by an air compressor, the pressure in the air tank is increased to a predetermined pressure, and air at a predetermined pressure is supplied from the air tank to a load such as an air brake.
The air compressor supplies air to the air tank by performing a compression operation until the pressure in the air tank falls below a predetermined pressure until the pressure reaches the predetermined pressure (load state).

On the other hand, even when the pressure in the air tank reaches a predetermined pressure, the air compressor is linked to the driving of the engine, and the piston always reciprocates in the cylinder of the air compressor (unloading). Status). Therefore, a discharge-side valve that closes the discharge passage and a suction-side valve that closes the suction passage are provided during unloading, and the supply of compressed air to the air tank is stopped during unloading.

However, since air is not supplied into the cylinder at the time of unloading, during unloading operation, air in the cylinder leaks from the gap between the cylinder and the piston into the crank chamber, and the pressure in the cylinder decreases. There is a disadvantage that the pressure becomes negative. When the pressure in the cylinder becomes negative, oil in the crank chamber rises, and the compressed air contains a large amount of oil or carbon. Therefore, the discharge side valve or the like may malfunction due to the adhesion of the oil or carbon. is there.

On the other hand, Japanese Patent Application Laid-Open No. Hei 7-293446 discloses that an air leak hole having a predetermined ventilation resistance is formed between a valve body and a valve seat of a suction side unloader valve when the suction side valve is closed. At the time of unloading, when the piston descends, air is supplied into the cylinder from the air leak hole to compensate for air blow-by from between the cylinder and the piston, and the negative pressure in the cylinder is maintained by maintaining the cylinder internal pressure at a predetermined pressure. Techniques for preventing pressure have been proposed.

[0006]

However, merely providing an air leak hole in the valve body of the suction-side unloader valve does not sufficiently supply air when the cylinder descends.
The negative pressure in the cylinder cannot be sufficiently prevented. Even such a slight negative pressure may cause oil to rise from the crank chamber into the cylinder. Further, if the unload operation is performed for a long time, the internal pressure of the cylinder changes due to disturbance due to a change in the engine speed or the like, and it is difficult to prevent a negative pressure in the cylinder due to blow-by.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an air compressor which can sufficiently prevent an oil rise due to a negative pressure in a cylinder during an unload operation.

[0008]

In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that a suction passage for supplying air through a suction valve into a cylinder in which a piston reciprocates, and a discharge valve through a discharge valve. A discharge passage for discharging compressed air to the air tank, a discharge-side unloader valve for opening and closing the discharge passage in response to pressure in the air tank, a dead volume space,
Provided separately from the suction passage and discharge passage
A communication path communicating with the volume space, and a dead volume side unloader valve that opens and closes the communication path in response to the pressure in the air tank, and when the pressure in the air tank becomes a predetermined pressure or more, the discharge side unloader valve is used. It is characterized by closing and opening the dead volume side unloader valve.

According to the first aspect of the present invention, when the internal pressure of the air tank becomes equal to or higher than a predetermined pressure, the air compressor performs an unloading operation. In the unloading operation, the piston in the cylinder continues the reciprocating motion. And
The discharge-side unloader valve closes the discharge passage in response to the pressure from the air tank and opens the dead volume-side unloader valve.

In the unload operation, when the piston is lowered, air is supplied from the suction passage through the suction valve, and when the piston is raised, the air in the cylinder is compressed to maintain the pressure in the cylinder at a predetermined pressure. Prevent negative pressure. As described above, during the unload operation, since the air is sufficiently supplied to the suction passage with little resistance, it is possible to prevent the generation of the negative pressure in the cylinder and to prevent the oil from flowing into the cylinder.

When the piston is raised, the air in the cylinder is compressed. However, the compressed air is compressed in the volume of the cylinder space and the dead volume space. Can be substantially increased. For example, even if the reciprocating speed of the piston changes due to a change in the engine speed, the cylinder internal pressure can be maintained at a predetermined pressure, and the cylinder is stable. In particular, it is stable against long-time unload operation, and prevents generation of negative pressure due to blow-by.

Further, since the negative pressure can be prevented, the compression ratio of air when the piston is raised and lowered can be reduced, and the load on the air compressor can be reduced. Further, by preventing the generation of the negative pressure, the suction valve hardly operates when the unload operation is in a stable state, so that it is possible to prevent the oil from flowing up to the suction passage.

According to a second aspect of the present invention, in the first aspect of the invention, the dead volume side unloader valve is provided in a valve cylinder having a valve hole, a valve body, and a hollow inside the valve cylinder. A biasing means for biasing the valve body in the direction to close the valve hole, and a pressure receiving portion for receiving the air tank pressure and moving the valve body in the opening direction of the valve hole are provided, and the dead volume space is a valve cylinder space. When the pressure receiving portion receives a predetermined pressure from the air tank, a valve hole is opened and a dead volume space in the valve cylinder communicates with the inside of the cylinder.

According to the second aspect of the invention, the same operation and effect as those of the first aspect of the invention can be obtained.
Since the dead volume space of the unloader valve on the dead volume side is used as a dead volume space, there is no need to separately form a dead volume space in a cylinder head or the like, so that space efficiency can be improved and the device can be downsized. .

According to a third aspect of the present invention, in the first aspect of the present invention, the dead volume side unloader valve includes a valve body, a valve body having a hollow sliding inside the valve body, and a valve body having a hollow body. A valve provided in the hollow for urging the valve body in a direction to close the valve hole, and a pressure receiving portion provided on the valve body for receiving the air tank pressure and moving the valve body in the opening direction, the valve comprising: The body is provided with a through hole communicating between the hollow interior and the cylinder interior.

According to the third aspect of the invention, the same operation and effect as those of the first aspect of the invention can be obtained.
Since the cylindrical valve body has a through hole communicating between the inside of the cylinder and the hollow body of the valve body, the biasing force provided in the hollow body of the valve body is not affected by the pressure of the cylinder chamber. The urging force of the means can be applied to the valve body as it is, so that the dead volume side unloader valve can be opened and closed stably.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the dead volume space is a space between the discharge-side unloader valve and the discharge valve in the discharge passage. .

According to the fourth aspect of the invention, the same operation and effect as those of the first aspect of the invention can be obtained.
When the discharge-side unloader valve and the discharge valve are closed, a part of the discharge passage between them becomes a closed space, and this closed space is used as a dead volume space. Since the discharge passage is used as the dead volume space, there is no need to separately form a dead volume space in the cylinder head or the like, so that space efficiency can be improved and the device can be downsized.

[0019]

An air compressor according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

First, a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG.
The air compressor 1 according to the first embodiment is provided in an air piping system 3 of a vehicle.
And the air tank 5 are connected via an air dryer 7 and a check valve 9 so that the air sucked and compressed by the air compressor 1 is dehumidified by the desiccant of the air dryer 7 and then supplied to the air tank 5 to be accumulated. It has become. The air stored in the air tank 5 is supplied to an air brake or the like.

The air tank 5 is further connected to a pressure transmission passage 13 (described later) of the air compressor 1 via a governor 11, and when the pressure in the air tank 5 becomes higher than a predetermined pressure, the governor 11 is opened. Air compressor 1
In the unloaded state, the supply of the compressed air to the air tank 5 is stopped, and when the pressure becomes lower than a predetermined pressure, the governor 11 is closed to put the air compressor 1 in the loaded state and the air tank 5
Supply of compressed air to the

As shown in a schematic configuration in FIG. 1, the air compressor 1 includes a cylinder 15 and a piston 17 reciprocating in the cylinder 15.
Connecting rod 2 arranged in crank chamber 19
The piston 17 is reciprocated in accordance with the driving of the engine to change the volume of the compression chamber (cylinder chamber) 23.

A cylinder head 27 is fixedly mounted on the upper part of the cylinder 15 via an intermediate member 25. The intermediate member 25 has a suction hole 2 for introducing air into the cylinder 15.
9, a discharge hole 31 for discharging compressed air in the cylinder 15,
And a communication hole 35 communicating with a dead volume space (described later) 33. A suction valve 37 is provided at an opening end of the suction hole 29 on the cylinder side, and a discharge valve 39 is provided at an opening end of the discharge hole 31 on the cylinder head 27 side.

The cylinder head 27 has a suction passage 41,
The discharge passage 43, the pressure transmission passage 13, and the dead volume space 33 are formed. The suction passage 41 communicates with the suction hole 29, and the discharge passage 43 communicates with the discharge hole 31. The discharge passage 43 is provided with a discharge-side unloader valve 45 that opens and closes. The discharge-side unloader valve 45 operates by receiving the pressure of the pressure transmission passage 13, and closes when the pressure in the pressure transmission passage 13 exceeds a predetermined pressure and opens when the pressure in the pressure transmission passage 13 becomes lower than the predetermined pressure.

The dead volume space 33 is communicated with a communication hole 35 through a passage 47. The passage 47 is provided with a dead volume side unloader valve 49 which opens and closes by receiving the pressure of the pressure transmission passage 13. Transmission passage 1
3 is opened when the pressure becomes higher than a predetermined value, and closed when the pressure is lower than the predetermined pressure.

FIGS. 2 and 3 show the discharge-side unloader valve 4.
5 and the specific configuration of the dead volume side unloader valve 49 are shown. FIG. 2 shows a case where the air compressor is in a loaded state, and FIG. 3 shows a case where the air compressor is in an unloaded state.

The discharge-side unloader valve 45 includes a valve body 51.
, A valve cylinder 53, and a pressure receiving portion 55 slidable in the valve cylinder 53.
A rod 57 connecting the valve body 51 and the pressure receiving portion 55;
A fixing member 59 provided on the valve body 51 side of the valve cylinder 53; the fixing member 59 and the rod 57;
A spring 62 is attached to 9 and the pressure receiving portion 55. The spring 62 urges the valve body 51 so as to be located on the fixing member 59 side. A valve seat portion 61 of the valve body 51 is formed in the discharge passage 43, and when the pressure receiving portion 55 moves (moves rightward in the drawing) against the spring 62, the valve body 51 sits on the valve seat portion 61. Thus, the discharge passage 43 is closed.

Dead volume side unloader valve 49
Is a valve cylinder 63 and a cylindrical valve body 6 slidable in the valve cylinder 63.
5 and a fixed portion 67 fixed to the cylinder head 27. The valve body 65 and the fixed portion 67 have a spring 6
8, which urges the valve body 65 in a direction in which the valve body 65 is seated on the valve seat portion 69 (to the right in FIG. 2).

A through hole 71 penetrating the inside and outside of the cylindrical valve body 65 is formed at the tip (seating side) of the valve body 65.
The inside and outside of the valve body 65 communicate with each other so that only the urging force of the spring 68 acts on the valve body 65.

A pressure receiving space 73 is formed in the valve cylinder 63, and the valve body 65 receives the pressure of the pressure receiving space 73 and moves away from the valve seat 69 against the urging force of the spring 68 (see FIG. 4). (Middle left). This pressure receiving space 73
Is connected to the pressure transmission passage 13 via the passages 75 and 77.

Next, the operation of the present embodiment will be described. When the pressure in the air tank 5 is equal to or lower than a predetermined value, it is in a load state, and compressed air is supplied from the air compressor 1 to the air tank 5. In this load state, the governor 11
Is closed, and the pressure in the air tank 5 does not act on the pressure transmission passage 13. As shown in FIG. 2, in the discharge-side unloader valve 45, the pressure receiving portion 55 is moved in accordance with the urging force of the spring 62. Located on the pressure transmission passage 13 side, the valve element 61 is located at a position away from the valve seat 61 and opens the discharge passage 43.

Dead volume side unloader valve 49
In this case, since no pressure is applied to the pressure receiving space 73, the valve body 65 is seated on the valve seat 69 by the urging force of the spring 68. Therefore, the dead volume space 33 and the compression chamber 23 of the cylinder 15 are in a closed state.

In this load state, the air sucked from the suction passage 41 and compressed in the cylinder 15 is supplied to the air tank 5 from the discharge passage 43 by the reciprocating motion of the piston 17.

On the other hand, when the pressure in the air tank 5 exceeds a predetermined pressure, the governor 11 is opened, the pressure in the air tank is introduced into the pressure transmission passage 13, and the air compressor 1 is brought into an unloaded state. In this case, the discharge-side unloader valve 4
In FIG. 5, since a predetermined pressure or more is applied to the pressure transmission passage 13, as shown in FIG. 3, the pressure receiving portion 55 moves against the urging force of the spring 62 by this pressure, and the valve body 51 moves to the valve seat 61. The user sits down and closes the discharge passage 43.

Dead volume side unloader valve 49
Then, the pressure in the pressure transmission passage 13 is introduced into the pressure receiving space 73 through the passages 77 and 75, and the valve body 65 moves in a direction away from the valve seat 69 against the urging force of the spring 68 by this pressure. , Open the passage 47 and, as shown in FIG.
The dead volume space 33 communicates with the communication hole 35.

In this unloaded state, the discharge side unloader valve 45 is closed, so that no compressed air is supplied to the air tank 5. On the other hand, since the piston 17 reciprocates with the driving of the engine, the compression of air is repeated in the cylinder 15. Since the suction passage 41 is not provided with an unloader valve, the suction passage 41 can be sucked through the suction valve 37.

When the piston is lowered in the unloaded state, air is supplied from the suction passage 41 through the suction valve 37. When the piston is raised, the air is compressed by the total volume of the compression chamber 23 and the dead volume space 33, and the cylinder is compressed. 15 to maintain the pressure in the compression chamber 15 at a predetermined pressure.
Prevent negative pressure in 3. As described above, the generation of the negative pressure in the compression chamber 23 during the unload operation can be prevented, so that the oil in the cylinder 15 can be prevented from rising.

In the stable state, when the piston 17 is raised, the air in the cylinder 15 is compressed. However, since the air is compressed in the combined volume of the compression chamber 23 and the dead volume space 33, the air is compressed. The volume of the compression chamber 23 in the descending process can be increased, and the inside of the cylinder 15 can be maintained at a predetermined pressure even if the reciprocating speed of the piston 17 changes due to a change in the engine speed or the like. Hard to do.

Here, the piston 17 during stable operation is
FIG. 4 shows the relationship between the pressure and the volume in the cylinder 15 due to the reciprocating motion of. FIG. 4 shows the volume (V) on the horizontal axis and the pressure P on the vertical axis.
, And a conventional example is indicated by a broken line R. As is clear from the graph of FIG. 4, in the present embodiment M, the reciprocating motion of the piston 17 does not reach a negative pressure when the piston descends, and the compression ratio S accompanying the reciprocating motion of the piston is indicated by a broken line. It is clear that it is smaller.

Further, as is apparent from FIG. 4, the occurrence of negative pressure in the cylinder 15 during the unloading operation can be prevented, so that oil rising into the cylinder 15 is prevented. Further, since the generation of the negative pressure is prevented, the suction valve 37 hardly operates, so that the rise of oil toward the suction passage 41 can be prevented.

Next, second to fourth embodiments of the present invention will be described with reference to FIGS. In the embodiment described below, portions having the same functions and effects as those of the above-described first embodiment are denoted by the same reference numerals, detailed description of those portions is omitted, and the first embodiment is mainly described. Only the differences from the embodiment will be described.

In the second embodiment shown in FIG. 6, the configuration of the dead volume side unloader valve 49 is different from that of the above-mentioned embodiment, and the dead volume space 33 is not separately provided in the cylinder head 27, and the dead volume space is not provided. 33 is formed in the dead volume side unloader valve 49.

That is, the dead volume side unloader valve 49 includes a valve body 81, a valve cylinder 83, a pressure receiving portion 85 slidable in the valve cylinder 83, and a rod 87 connecting the valve body 81 and the pressure receiving portion 85. And a valve seat 8 provided on the valve body side of the valve cylinder 83.
The valve seat 89 has a valve hole 90 formed therein.
A spring 91 is mounted on the valve seat 89 and the rod 87, and on the valve seat 89 and the pressure receiving portion 83.
1 urges the valve body 81 in a direction in which the valve body 81 is seated on the valve seat 89. A dead volume space 33 is formed in the valve cylinder 83 between the valve seat 89 and the pressure receiving portion 85. With this configuration, in the unload state, when the pressure receiving portion 85 receives the pressure from the pressure transmission passage 13, the valve body 81 moves against the urging force of the spring 91, opens the valve hole 90, and opens the dead volume space. 33 communicates with the compression chamber 23 of the cylinder 15.

In the second embodiment, the same operation as in the above-described embodiment is achieved, and the cylinder head 2
Since only the dead volume side unloader valve 49 is provided in 7, there is no need to separately provide the dead volume space 33, so that the apparatus can be downsized. Further, the dead volume side unloader valve 49 has the same configuration as the discharge side unloader valve 45, and since the same valve can be used, the configuration is simple and the manufacturing is easy.

In the third embodiment shown in FIG. 7, a dead volume side unloader valve 49 having the same structure as that of the second embodiment is provided, and a separate dead volume space 33 is formed in the cylinder head 27 so that the dead volume side The unloader valve 49 is opened to connect the compression chamber 23 of the cylinder 45 with the dead volume space 33. Also in the third embodiment, the dead volume side unloader valve 49 has the same configuration as the discharge side unloader valve 45, and since the same valve can be used, the configuration is simple and the manufacturing is easy.

In the fourth embodiment shown in FIG. 8, the dead volume space 33 is formed between the discharge side unloader valve 45 and the discharge valve 39 in the discharge passage 43.
The discharge passage 43 is used as the dead volume space 33. The dead volume space 33 communicates with the compression chamber 23 of the cylinder 15 through a communication passage 92, and the dead volume side unloader valve 49 opens and closes the communication passage 92. Reference numeral 94 in the pressure receiving space 73 denotes an opening of a passage communicating with the pressure transmission passage 13. In the fourth embodiment, as shown in FIG. 8, when the discharge-side unloader valve 45 and the discharge valve 39 are closed, a part of the discharge passage 43 between them becomes a closed space. It is used as a volume space 33. Therefore, it is not necessary to separately form a dead volume space in the cylinder head or the like, and the space efficiency can be improved.

The present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention.

[0048]

According to the first aspect of the present invention, during unloading operation, when the piston is lowered, air is supplied from the suction passage via the suction valve, and when the piston is raised, the air in the cylinder is compressed and the cylinder is compressed. Since the internal pressure is maintained at a predetermined pressure, negative pressure in the cylinder can be prevented and oil can be prevented from flowing into the cylinder.

Further, since the compressed air is compressed in a volume portion including the inside of the cylinder and the dead volume space, the pressure fluctuation can be reduced with respect to disturbances such as a change in the engine speed and the like. Prevents the generation of pressure.

Since the negative pressure in the cylinder chamber can be prevented, the compression ratio in the step of raising and lowering the piston can be reduced, and the load on the air compressor during the unload operation can be reduced.

Further, since the negative pressure in the cylinder chamber can be prevented, the suction valve hardly operates, so that oil rising to the suction passage side can be prevented.

According to the invention described in claim 2, according to claim 1
In addition to the same operation and effect as the invention described in (1), since the inside of the valve cylinder of the dead volume side unloader valve is used as a dead volume space, it is not necessary to separately form a dead volume space, and space efficiency is improved. And the size of the device can be reduced.

According to the invention of claim 3, according to claim 1,
In addition to the same operation and effect as the invention described in (1), since the cylindrical valve body is formed with a through hole communicating the cylinder side and the hollow of the valve body, it is affected by the pressure of the cylinder chamber. And the opening and closing of the valve element can be performed stably.

According to the invention set forth in claim 4, according to claim 1,
In addition to having the same effect as the invention described in the above, since the discharge passage is used as a dead volume space,
There is no need to separately form a dead volume space in the cylinder head or the like, so that space efficiency can be improved and the device can be downsized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an air compressor according to a first embodiment.

FIG. 2 is a sectional view of the air compressor in a load state.

FIG. 3 is a sectional view of the air compressor in an unloaded state.

FIG. 4 is a graph showing a relationship between a volume of air in a cylinder and a pressure in an unloaded state.

FIG. 5 is a configuration diagram of an air supply system equipped with the air compressor according to the present embodiment.

FIG. 6 is a sectional view of a cylinder head showing a dead volume side unloader valve according to a second embodiment.

FIG. 7 is a sectional view of a cylinder head showing a dead volume side unloader valve according to a third embodiment.

FIG. 8 is a cross-sectional view illustrating a configuration of an air compressor according to a fourth embodiment.

[Explanation of symbols]

 Reference Signs List 1 air compressor 15 cylinder 17 piston 23 compression chamber (in cylinder) 33 dead volume space 37 suction valve 39 discharge valve 41 suction passage 43 discharge passage 45 discharge unloader valve 49 dead volume unloader valve 71 through hole 92 communication passage

Continuation of the front page (56) References JP-A-7-293446 (JP, A) JP-A-8-193576 (JP, A) JP-A 1-179184 (JP, U) JP-A 59-30575 (JP) , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04B 39/10 F04B 49/00-51/00

Claims (4)

(57) [Claims] 1. A suction passage for supplying air through a suction valve into a cylinder in which a piston reciprocates, a discharge passage for discharging compressed air to an air tank through a discharge valve, and a pressure response in the air tank. A discharge-side unloader valve for opening and closing the discharge passage, a dead volume space, a suction passage,
Provided separately from the discharge passage and empty inside the cylinder and dead volume
And a dead volume side unloader valve that opens and closes the communication path in response to the pressure in the air tank, and the discharge side unloader valve closes when the air tank pressure exceeds a predetermined pressure. An air compressor characterized by opening a dead volume side unloader valve. 2. The unloader valve on the dead volume side, a valve body having a valve hole, a valve body, and biasing means provided in the hollow of the valve cylinder to bias the valve body in a direction to close the valve hole. And a pressure receiving portion that moves the valve body in the opening direction of the valve hole in response to the air tank pressure, and the dead volume space is a space in the valve cylinder, and opens the valve hole when the pressure receiving portion receives a predetermined pressure from the air tank. The air compressor according to claim 1, wherein the dead volume space in the valve cylinder communicates with the inside of the cylinder. 3. The unloader valve on the dead volume side has a valve body, a valve body having a hollow sliding in the valve body,
A biasing means provided in the hollow of the valve body and biasing the valve body in a direction to close the valve hole, and a pressure receiving portion provided on the valve body and receiving the air tank pressure to move the valve body in the opening direction are provided. The air compressor according to claim 1, wherein the valve body has a through hole that communicates between the inside of the hollow and the inside of the cylinder. 4. The dead volume space between the discharge-side unloader valve and the discharge valve in the discharge passage.
The air compressor according to claim 1, wherein the air compressor is a space .