JP4015219B2 - Air compressor load reducing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a load reducing device for an air compressor that is preferably used for supplying compressed air to pneumatic equipment such as an air motor and an air cylinder, and more particularly, to perform no-load operation when the pressure of the compressed air increases greatly. The present invention relates to a load reducing device for an air compressor that can be performed.
[0002]
[Prior art]
Generally, a crankcase in which a crankshaft is rotatably provided, a cylinder mounted on the crankcase, a cylinder head provided on the cylinder and defining a compression chamber, and a cylinder head, A suction chamber and a discharge chamber provided in the cylinder head independently of each other, an electric motor provided in the crankcase as a drive source for rotationally driving the crankshaft, and provided on the suction chamber side at all times. A reciprocating air compressor comprising an unloading mechanism that allows the suction valve to open and close in accordance with the reciprocating motion of the valve and keeps the suction valve open during no-load operation is disclosed in, for example, -61235 and the like.
[0003]
In this type of conventional air compressor, the crankshaft is driven to rotate by an electric motor and the piston is reciprocated in the cylinder to compress the air sucked from the suction chamber side while compressing the compressed air. A so-called compression operation is performed in which discharge is performed from the discharge chamber to an external air tank or the like.
[0004]
Then, when the pressure in the air tank rises to a predetermined maximum set pressure by this compression operation, the unload mechanism is operated to forcibly open the suction valve, and the compression chamber is opened to the suction valve and the suction chamber. By communicating with the atmosphere through the no-load operation, no-load operation is performed while the electric motor continues to rotate.
[0005]
Here, the unload mechanism includes an electromagnetic actuator that is located on the suction chamber side and provided in the cylinder head, and an unload piston that pushes the suction valve by being driven by the electromagnetic actuator. In the normal compression operation, the unloading piston is separated from the suction valve to allow the suction valve to be opened and closed in accordance with the reciprocation of the piston.
[0006]
Then, when the pressure in the air tank rises to the maximum set pressure by the compression operation, the unloading piston is driven by the unloading piston by driving the unloading piston toward the suction valve side by the electromagnetic actuator. To forcibly open the valve and start unload operation as no-load operation.
[0007]
As a result, while the suction valve is kept open, the pressure in the compression chamber is maintained at the atmospheric pressure state even if the reciprocation of the piston is continued by the electric motor, thereby reducing the load on the electric motor. No-load operation can be performed.
[0008]
This also eliminates the need to start and stop the electric motor in response to pressure fluctuations in the air tank, thereby saving labor. Even when the electric motor is started to start the compression operation, the suction valve is opened for a predetermined time by the unload mechanism until the motor reaches the rated rotation so that the starting load can be reduced.
[0009]
[Problems to be solved by the invention]
By the way, in the above-described conventional technology, the unload piston is driven by the electromagnetic actuator during no-load operation, and at this time, the suction valve is forced to open by pushing the suction valve with the unload piston. The following problems occur.
[0010]
That is, in the prior art, for example, when the unloading mechanism is operated during the compression operation in which the suction valve is opened and closed as the piston reciprocates, the unloading piston driven by the electromagnetic actuator is The suction valve may collide strongly with the opening and closing operation, and the suction valve may be worn and damaged early due to the impact.
[0011]
In addition, when the piston in the cylinder is in the discharge (compression) stroke, the suction valve is closed to boost the compression chamber in the cylinder to a high pressure state with compressed air. When operating the mechanism, it is necessary to apply a large driving force to the unload piston by the electromagnetic actuator in order to forcibly open the suction valve with the unload piston against high pressure in the compression chamber. In particular, in a large compressor that generates high-pressure compressed air, the electromagnetic actuator or the like must be enlarged in order to increase the driving force of the unload piston by the electromagnetic actuator.
[0012]
On the other hand, in a multi-stage air compressor in which a plurality of cylinders (cylinders) are provided in the crankcase of the compressor body, the suction valve for each cylinder is forcibly opened by each unload mechanism during unload operation. What is configured is known. However, in this case, since an unload mechanism is provided for each cylinder, the number of parts increases, workability at the time of assembly decreases, and the control circuit of each unload mechanism becomes complicated. There is a problem that the manufacturing cost increases.
[0013]
Furthermore, as another conventional technique, for example, a check valve is provided between the air tank and the discharge chamber of the cylinder head to prevent the compressed air in the air tank from flowing back to the discharge chamber side and to discharge the cylinder head. Also known is a configuration in which an unloading mechanism for opening the discharge chamber to the atmosphere is provided on the chamber side.
[0014]
However, in this case, during normal compression operation, high-pressure compressed air is discharged from the discharge chamber side to the air tank via the check valve. Always exposed and prone to thermal degradation early. In order to prevent this, it is necessary to use a high-quality check valve that can withstand high temperatures, high pressures, high loads, etc., which not only increases costs but also checks high-quality ones. There is a problem that it is difficult to ensure operation stability (reliability) as a valve over a long period of time.
[0015]
The present invention has been made in view of the above-described problems of the prior art, and the present invention can easily perform no-load operation by opening the discharge chamber side to the atmosphere without using a check valve or the like, and has durability. Another object of the present invention is to provide an air compressor load reducing device that can improve reliability and the like.
[0016]
Another object of the present invention is to eliminate the need to provide an unload mechanism or the like for each cylinder even when applied to, for example, a multistage air compressor. An object of the present invention is to provide an air compressor load reducing device that can improve workability, simplify the overall structure, and extend durability and life.
[0017]
[Means for Solving the Problems]
  In order to solve the above-described problems, the present invention has at least a compression chamber and first and second discharge chambers, and includes the first and second discharge chambers and the compression chamber. A compressor main body provided with first and second discharge valves that are opened and closed independently of each other, and the compressor main body provided in the compressor main body for generating compressed air in the compression chamber A drive source for driving the machine main body, an air tank connected to one of the discharge chambers of the compressor main body, and storing compressed air discharged from the compression chamber through the one discharge chamber; In the other discharge chamber of the compressor bodyAt a distance through the conduitConnected and normally closed to keep the other discharge chamber in a high-pressure state and open during the no-load operation to open the other discharge chamber to the atmosphere, and to open and close the valve means The structure which consists of a valve drive means to adopt is adopted.
  According to the invention of claim 2, the compressor body is a multistage compressor body having a low pressure side compression chamber and a high pressure side compression chamber, and the valve means is the compressor body. Among these, it is set as the structure arrange | positioned in the compression chamber side of a high voltage | pressure side.
[0018]
  According to the above configuration,The invention described in claim 1Of the first and second discharge chambers provided in the compressor body, one discharge chamber is connected to the air tank, and the other discharge chamberProvided at a remote locationFor valve meansThrough the conduitWhen the valve means is opened by the valve driving means during no-load operation, the other discharge chamber can be opened to the atmosphere, and the compressor main body and The load on the drive source can be automatically reduced. Since the pressure from the air tank acts on the discharge valve on the one discharge chamber side, the discharge valve can be kept in a high pressure state by keeping the discharge valve closed, and stored in the air tank. It is possible to prevent the compressed air from leaking outside during no-load operation.
  According to the second aspect of the present invention, the valve means may be disposed on the high pressure side compression chamber side of the multistage compressor body having the low pressure side compression chamber and the high pressure side compression chamber. it can.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0020]
1 to 4 show an example in which the load reducing device for an air compressor according to an embodiment of the present invention is applied to a reciprocating two-stage air compressor.
[0021]
In the figure, reference numeral 1 denotes a compressor main body constituting the main body of the compressor. The compressor main body 1 is configured as a horizontally opposed two-stage compressor by a crankcase 2 and cylinders 5 and 10 described later. Yes. A crankshaft 3 is rotatably provided in the crankcase 2 of the compressor body 1, and the crankshaft 3 is rotationally driven by an electric motor 18 described later. Further, a cooling fan 4 is provided on the front end side of the crankshaft 3 protruding outward from the crankcase 2, and the cooling fan 4 is driven to rotate together with the crankshaft 3, so that the crankcase 2, the cylinders 5, 10, etc. It is the structure which generates the cooling wind which aimed at.
[0022]
Reference numeral 5 denotes a low-pressure side cylinder constituting the first cylinder provided in the crankcase 2, and 6 denotes a piston slidably inserted into the low-pressure side cylinder 5. The piston 6 is connected to the crankshaft 3. It is connected via the rod 7 and reciprocates in the low pressure side cylinder 5 as the crankshaft 3 is rotationally driven by the electric motor 18. A low pressure side compression chamber A is defined in the low pressure side cylinder 5 between the piston 6 and a cylinder head 8 described later.
[0023]
Reference numeral 8 denotes a cylinder head which is provided on the front end side of the low pressure side cylinder 5 and constitutes a first cylinder together with the low pressure side cylinder 5. The cylinder head 8 includes a suction valve for the compression chamber A of the low pressure side cylinder 5. A suction chamber and a discharge chamber (both not shown) that are communicated and cut off via the discharge valve are formed. The suction chamber of the cylinder head 8 communicates with outside air via a suction silencer (not shown) and the like, and external air is sucked into the compression chamber A of the low-pressure side cylinder 5 when the suction valve is opened. ing. Further, a discharge port 8A is provided on the discharge chamber side of the cylinder head 8, and the discharge port 8A is connected to a high-pressure side suction chamber C described later via a communication pipe 9.
[0024]
Reference numeral 10 denotes a high-pressure side cylinder constituting a second cylinder provided on the crankcase 2 located on the opposite side of the low-pressure side cylinder 5. The high-pressure side cylinder 10 is formed with a smaller cylinder diameter than the low-pressure side cylinder 5. High pressure compressed air is generated. Reference numeral 11 denotes a piston slidably fitted in the high-pressure side cylinder 10, and the piston 11 is connected to the crankshaft 3 via a connecting rod 12, and in the high-pressure side cylinder 10 as the crankshaft 3 rotates. Reciprocate.
[0025]
A cylinder head 13 is provided at the tip of the high-pressure side cylinder 10 and constitutes a second cylinder together with the high-pressure side cylinder 10. The cylinder head 13 is located between the piston 11 and the compression chamber B in the high-pressure side cylinder 10. Is forming. Further, the cylinder head 13 is provided with a valve plate 14 between the cylinder head 13 and the high-pressure side cylinder 10, and the valve plate 14 is provided in the cylinder head 13 with the suction chamber C and the first and second discharges as shown in FIG. The rooms D and E are defined.
[0026]
One of the discharge chambers D and E is connected to an air tank 19 (described later) via an air pipe 20, and the other discharge chamber E is connected to a release valve 21 (described later) via an unloading conduit 22. Connected through. Further, the valve plate 14 is provided with a suction valve 15 for connecting and blocking the compression chamber B of the high-pressure side cylinder 10 to the suction chamber C, and a first valve for connecting and blocking the compression chamber B to the discharge chambers D and E. , Second discharge valves 16 and 17 are provided.
[0027]
Here, the discharge valves 16 and 17 are composed of reed valves or the like, and are configured to open and close the discharge chambers D and E independently of the compression chamber B. Further, the cylinder head 13 is provided with a suction port 13A that is always in communication with the suction chamber C, and the suction port 13A is connected to the discharge port 8A on the low pressure side via the communication pipe 9.
[0028]
Reference numeral 18 denotes an electric motor as a drive source provided integrally with the crankcase 2 of the compressor body 1, and the motor case 18A of the electric motor 18 constitutes a part of the crankcase 2 as shown in FIG. It is integrally provided on one side of the crankcase 2. The rotating shaft 18B of the electric motor 18 is integrally connected to the crankshaft 3 in the crankcase 2 so that the crankshaft 3 is rotationally driven.
[0029]
Reference numeral 19 denotes an air tank for storing compressed air. The air tank 19 is formed as a substantially cylindrical sealed container as shown in FIG. 2. For example, compressed air is introduced into the air tank 19 on the upper side of the air tank 19. , A connecting pipe portion 19A is provided integrally. The air tank 19 is connected to a discharge chamber D formed in the high-pressure side cylinder head 13 via an air pipe 20, and the high-pressure compressed air generated in the compression chamber B of the high-pressure side cylinder 10 is discharged into the discharge chamber D. Is stored in the air tank 19 through the air pipe 20.
[0030]
  21 is a release valve as a valve means connected to the discharge chamber E of the cylinder head 13 via a conduit 22 for unloading.As shown in FIG. 2, the release valve 21 is connected to the conduit 22 at a position where the inflow port 23 </ b> B is away from the discharge chamber E of the cylinder head 13. AndAs shown in FIGS. 3 and 4, in the release valve 21, the piston sliding hole 23A is formed as a stepped hole in the axial direction, and the inflow port 23B and the pilot port 23C are separated in the axial direction of the piston sliding hole 23A. The valve housing 23 is screwed to one end side of the valve housing 23 so as to close one end side of the piston sliding hole 23A, and always communicates with the pilot port 23C between the stepped piston 29 described later. A plug body 25 that defines a pilot pressure chamber 24, a valve body 30 described later, and the like are configured.
[0031]
Here, on the other end side of the valve housing 23, an enlarged diameter hole 23E that forms an annular valve seat 23D is provided between the other end face of the piston sliding hole 23A. 23 is covered with a cover cylinder 26 that constitutes a part of 23. The cover cylinder 26 defines an air release chamber 27 between the diameter expansion hole 23E, and the air release chamber 27 is always in communication with the outside air via a silencer filter 28 made of porous sintered metal or the like. It has a configuration.
[0032]
29 is a stepped piston inserted into the piston sliding hole 23A of the valve housing 23. The stepped piston 29 has a small diameter shaft portion 29A extending coaxially toward the diameter expansion hole 23E side. A valve body 30 formed in a short cylindrical shape is integrally fixed to the distal end side of the portion 29 </ b> A via a nut 31. An annular valve seat 32 is provided on one end side of the valve body 30, and the valve seat 32 is attached to and detached from the annular valve seat 23 </ b> D of the valve housing 23 together with the valve body 30.
[0033]
Here, the stepped piston 29 receives the pressure from the inflow port 23B on the end face 29B side, and is pressed in the direction indicated by the arrow F in FIG. 3 while the pilot pressure chamber 24 side is in the atmospheric pressure state. Accordingly, the stepped piston 29 causes the valve body 30 to be seated on the annular valve seat 23 </ b> D via the valve seat 32, and the inflow port 23 </ b> B is blocked from the atmosphere release chamber 27.
[0034]
On the other hand, when high-pressure compressed air is supplied into the pilot pressure chamber 24 via a pipe 35 described later, the stepped piston 29 receives this pressure on the end face 29C side. Since the stepped piston 29 has a larger pressure receiving area on the end surface 29C side than on the end surface 29B side, the stepped piston 29 is stepped even when the pressure is almost equal between the inflow port 23B and the pilot port 23C. The piston 29 is pressed in the direction indicated by the arrow G due to the pressure receiving area difference between the end faces 29B and 29C.
[0035]
As a result, when the valve body 30 is separated from the annular valve seat 23 </ b> D of the valve housing 23 together with the valve seat 32, the valve body 30 is opened and the inflow port 23 </ b> B communicates with the atmosphere release chamber 27. Then, the compressed air flowing from the inflow port 23B side to the atmosphere opening chamber 27 is discharged to the outside through the sound deadening filter 28. As a result, the discharge chamber E of the cylinder head 13 shown in FIG. 2 is opened to the atmosphere by the release valve 21 via the unloading conduit 22, and is connected to the discharge chamber E via the discharge valve 17. The pressure in the inner compression chamber B automatically decreases to a state close to atmospheric pressure by opening the release valve 21.
[0036]
In addition, the muffler filter 28 reduces the exhaust sound of the compressed air discharged from the atmosphere release chamber 27 toward the outside of the cover cylinder 26 at this time, suppresses the generation of noise, and external dust or the like is removed from the atmosphere release chamber 27. Intrusion to the inside is prevented, and the sliding surfaces of the valve seat 32 and the stepped piston 29 are prevented from being worn and damaged at an early stage by dust.
[0037]
Further, the silencing filter 28 has a porous structure, thereby giving a compression resistance to the compressed air discharged from the atmosphere opening chamber 27 to the outside, and slightly reducing the atmospheric opening chamber 27 side by a constant pressure from the atmospheric pressure. Create high pressure. Thus, for example, when switching from no-load operation (unload operation) to compression operation, if the pilot pressure chamber 24 side is set to the atmospheric pressure state, the atmosphere release chamber 27 side is set to a pressure at least higher than the atmospheric pressure. Therefore, when the end surface 29B side of the stepped piston 29 receives higher pressure than the end surface 29C side, the stepped piston 29 is pressed in the direction indicated by the arrow F in FIG. At the same time, it is seated on the annular valve seat 23D of the valve housing 23, and the release valve 21 is automatically closed.
[0038]
33 is an electromagnetic valve as a valve driving means for opening and closing the release valve 21. The electromagnetic valve 33 is constituted by a three-way electromagnetic valve having an inflow port 33A, an outflow port 33B, and an outflow port 33C. Is connected to the connecting pipe portion 19 </ b> A of the air tank 19 through a pipe 34. The electromagnetic valve 33 has an outlet 33B serving as an air opening, and the outlet 33C is connected to the pilot port 23C of the release valve 21 via a pipe 35.
[0039]
Here, the electromagnetic valve 33 normally connects the outflow port 33C to the outflow port 33B and blocks the inflow port 33A from the outflow port 33B and the outflow port 33C by a control signal from the control device 36 described later. At this time, the pilot port 23C of the release valve 21 is opened to the atmosphere via the pipe 35 and the outflow inlet 33C and outflow port 33B of the electromagnetic valve 33, so that the pilot pressure chamber 24 of the release valve 21 is as shown in FIG. The atmospheric pressure state is reached, and the stepped piston 29 holds the valve body 30 in a closed state by the pressure on the inflow port 23B side.
[0040]
When the solenoid valve 33 is controlled to be switched by a control signal from the control device 36, the inlet 33A of the solenoid valve 33 communicates with the outlet 33C, and the outlet 33B is shut off from the inlet 33A and the outlet 33C. Is done. As a result, the compressed air in the air tank 19 is supplied to the pilot pressure chamber 24 of the release valve 21 via the pipe 34, the inlet 33A of the electromagnetic valve 33, the outlet 33C, and the pipe 35. As the pressure in the tank 19 becomes substantially the same, the stepped piston 29 of the release valve 21 is pressed in the direction indicated by the arrow G as shown in FIG. 4, and the valve body 30 is forced against the pressure on the inlet port 23B side. Open the valve.
[0041]
Further, reference numeral 36 denotes a control device for switching and controlling the electromagnetic valve 33. The control device 36 has a voltage detector on the input side and is connected to a power supply line of the electric motor 18 and the output side is connected to the electromagnetic valve 33. . Here, the electric motor 18 is connected to a commercial power source (not shown) or the like at the tip end of the power supply line via the outlet 37, and the voltage value fed from the power source to the electric motor 18 is the load state of the electric motor 18. It is known to vary accordingly.
[0042]
Therefore, the control device 36 detects the voltage value supplied from the power source to the electric motor 18 by the voltage detector, thereby monitoring (monitoring) the load state of the electric motor 18. When the voltage value is at a normal voltage level, it can be determined that the electric motor 18 is in a normal compression operation state. Therefore, the control device 36 excites the electromagnetic valve 33 with a control signal, and the inlet / outlet of the electromagnetic valve 33 is 33C is connected to the outflow port 33B, and the inflow port 33A is blocked from the outflow port 33B and the outflow port 33C.
[0043]
On the other hand, when the pressure of the compressed air generated in the high pressure side cylinder 10 becomes higher than the set pressure on the air tank 19 side, the compression chambers A and B (see FIG. 1) of the compressor body 1 are in a relatively high pressure state. When the high pressure acts on the pistons 6 and 11, the rotational load of the crankshaft 3 increases, and the electric motor 18 receives a large rotational load. In this case, when the voltage value decreases according to the load of the electric motor 18, the control device 36 demagnetizes the electromagnetic valve 33 to perform switching control of the electromagnetic valve 33. The inlet 33A is communicated with the outlet 33C, and the outlet 33B is blocked from the inlet 33A and the outlet 33C.
[0044]
The load reducing device for a two-stage air compressor according to this embodiment has the above-described configuration, and the operation thereof will be described next.
[0045]
First, when the crankshaft 3 is rotationally driven by the rotary shaft 18B of the electric motor 18, the pistons 6 and 11 are reciprocated in the cylinders 5 and 10, and the compressed operation for generating compressed air in the compression chambers A and B is performed. Is done. The compressed air generated in the compression chamber A of the low pressure side cylinder 5 by this compression operation is discharged from the discharge port 8A of the cylinder head 8 into the suction chamber C of the high pressure side cylinder 10 through the communication pipe 9.
[0046]
Then, in the compression chamber B of the high pressure side cylinder 10, the compressed air is sucked from the suction chamber C according to the reciprocating motion of the piston 11, and compressed to a higher pressure level, thereby discharging the high pressure compressed air to the discharge valve. 16 and 17 are discharged into the discharge chambers D and E, respectively.
[0047]
In this case, since the release valve 21 is kept closed in the normal compression operation state, the pressure is applied to the discharge chamber E side connected to the inflow port 23B of the release valve 21 via the unloading conduit 22. The pressure is increased faster than the air tank 19. When the pressure in the discharge chamber E becomes higher than that in the compression chamber B of the high-pressure side cylinder 10, the discharge valve 17 is kept closed even when the piston 11 reciprocates.
[0048]
On the other hand, on the discharge chamber D side connected to the air tank 19 via the air pipe 20, the discharge valve 16 continues to open and close in accordance with the reciprocating motion of the piston 11, so that the compression chamber B of the high pressure side cylinder 10. The high-pressure compressed air generated therein is discharged into the discharge chamber D when the discharge valve 16 is opened, and this compressed air is sequentially stored in the air tank 19 via the air pipe 20.
[0049]
During this compression operation, the voltage value supplied to the electric motor 18 from the power source is maintained at a normal voltage level, so that the control device 36 continues to excite the electromagnetic valve 33 and flows through the outlet 33C of the electromagnetic valve 33. The pilot pressure chamber 24 of the release valve 21 is set to an atmospheric pressure state by communicating with the outlet 33B and blocking the inlet 33A from the outlet 33B and the outlet 33C.
[0050]
Next, when the pressure in the air tank 19 rises to the set pressure level during the compression operation as described above, the compression chambers A and B (see FIG. 1) of the compressor body 1 are relatively moved. Since the pressure is high, the electric motor 18 receives a large rotational load. When the voltage value decreases to a predetermined voltage value according to the load of the electric motor 18, the control device 36 performs switching control of the electromagnetic valve 33 so that the electromagnetic valve 33 is automatically demagnetized, The solenoid valve 33 communicates the inlet 33A with the outlet 33C and blocks the outlet 33B.
[0051]
Thereby, the compressed air in the air tank 19 is supplied to the pilot pressure chamber 24 of the release valve 21 through the pipe 34, the electromagnetic valve 33 and the pipe 35, and the inside of the pilot pressure chamber 24 reaches a pressure almost equal to that of the air tank 19. To rise. The stepped piston 29 of the release valve 21 receives the pressure from the pilot pressure chamber 24 on the end surface 29C side, and the end surface 29C side has a larger pressure receiving area than the end surface 29B side by the small diameter shaft portion 29A of the stepped piston 29. Therefore, the stepped piston 29 is pressed in the direction indicated by the arrow G as shown in FIG. 4 to forcibly open the valve body 30 against the pressure on the inflow port 23B side.
[0052]
As a result, the valve body 30 of the release valve 21 is separated from the annular valve seat 23D of the valve housing 23 together with the valve seat 32, and the inflow port 23B is communicated with the atmosphere release chamber 27, whereby the cylinder head 13 shown in FIG. The discharge chamber E is opened to the atmosphere through the unloading conduit 22 and the like. The compression chamber B in the high-pressure side cylinder 10 communicated with the discharge chamber E via the discharge valve 17 is dropped to the atmospheric pressure state by opening the release valve 21, so that the compression in the low-pressure side cylinder 5 is performed. The pressure in the chamber A also decreases to the atmospheric pressure level, and the compressor body 1 is unloaded (no load) operation, so that the load on the electric motor 18 can be automatically reduced.
[0053]
Further, when the electric motor 18 in a state where the compressed air has been stored in the air tank 19 in advance, for example, once stopped, is started again, an activation load acts on the electric motor 18, The voltage value supplied from the power source to the electric motor 18 may greatly decrease. In this case as well, the control device 36 switches and controls the electromagnetic valve 33 to introduce the pressure in the air tank 19 into the pilot pressure chamber 24 of the release valve 21 and open the release valve 21 at the time of startup. To reduce the load.
[0054]
Next, when the voltage value supplied to the electric motor 18 in this state rises to a normal voltage level, the control device 36 excites the electromagnetic valve 33 to cut off the inlet 33A of the electromagnetic valve 33. At the same time, the outlet 33C is communicated with the outlet 33B, and the pilot pressure chamber 24 of the release valve 21 is set to an atmospheric pressure state. As a result, the release valve 21 is closed again, and the compressor body 1 is compressed by the electric motor 18.
[0055]
Thus, according to the present embodiment, the first and second discharge chambers D and E are formed in the cylinder head 13 provided in the high pressure side cylinder 10, and one of the discharge chambers D is connected to the air tank 19 via the air pipe 20. The other discharge chamber E is connected to the inflow port 23B of the release valve 21 through the unloading conduit 22, and the pilot port 23C (pilot pressure chamber 24) side of the release valve 21 is connected to the pipe 35, electromagnetic Since it is configured to be connected to the air tank 19 via the valve 33 and the pipe 34, the following operational effects can be obtained.
[0056]
That is, the control device 36 that controls the switching of the electromagnetic valve 33 monitors the load state of the electric motor 18 and continues to excite the electromagnetic valve 33 until the load of the electric motor 18 becomes excessive, whereby the release valve 21 is controlled. The valve can be kept closed, and the compression operation can be continued while the discharge chamber E is kept in a high pressure state and the compressor body 1 is driven by the electric motor 18.
[0057]
When sufficient compressed air is stored in the air tank 19 by such a compression operation and the pressure in the air tank 19 rises to a level exceeding the set pressure, the load on the electric motor 18 increases. Therefore, the electromagnetic valve 33 can be demagnetized by a control signal from the control device 36 and the release valve 21 can be forcibly opened by the pressure from the air tank 19.
[0058]
As a result, the discharge chamber E can be opened to the atmosphere via the unloading conduit 22, and both the compression chambers B and A of the compressor body 1 can be reduced to the atmospheric pressure state. Unload operation can be performed, and the load on the electric motor 18 can be automatically reduced.
[0059]
In addition, the first and second discharge chambers D and E formed in the cylinder head 13 are individually communicated and blocked with respect to the compression chamber B via the first and second discharge valves 16 and 17. Thus, the discharge chambers D and E can be opened and closed independently of the compression chamber B by the discharge valves 16 and 17, respectively. For example, the discharge chamber E side is connected via the release valve 21 to perform no-load operation. Even when the air is released to the atmosphere, the discharge valve 16 can prevent the compressed air in the air tank 19 from flowing backward from the discharge chamber D to the compression chamber B side.
[0060]
Therefore, according to the present embodiment, two discharge chambers D and E are formed in the cylinder head 13, and the discharge chambers D and E are opened independently of the compression chamber B by the discharge valves 16 and 17, respectively. By adopting a closed configuration, for example, when the inside of the air tank 19 has a sufficiently high pressure without providing a check valve or the like in the middle of the air pipe 20 that connects one discharge chamber D to the air tank 19, By opening the other discharge chamber E side to the atmosphere via the release valve 21, no-load operation can be easily performed, and the load applied to the electric motor 18 can be automatically reduced.
[0061]
Further, since the discharge valves 16 and 17 provided between the compression chamber B and the discharge chambers D and E are constituted by a reed valve that opens and closes on the valve plate 14, the discharge valves 16 and 17 are at a high temperature. Can prevent early thermal degradation even when exposed to high-pressure compressed air, and can reliably improve the durability and life of the compressor. By switching to operation, the operation as a compressor can be stabilized and the reliability can be improved.
[0062]
Furthermore, by connecting the discharge chamber E formed in the high-pressure side cylinder head 13 to the release valve 21 via the unloading conduit 22, both the high-pressure side and the low-pressure side compression chambers B and A can be used during no-load operation. Since the load on the electric motor 18 can be reduced by reducing the pressure to the atmospheric pressure level, it is not necessary to provide an unload mechanism or the like for each cylinder as in the conventional multistage air compressor, and the number of parts can be reduced. It can be reduced and the workability during assembly can be improved.
[0063]
Furthermore, the release valve 21 serving as an unloading mechanism is constituted by a valve housing 23, a stepped piston 29, a valve body 30 and the like, and the valve body 30 is forcibly opened using the air pressure from the air tank 19. Therefore, there is no need to forcibly open the intake valve using a push rod or the like as in the conventional unload mechanism, and the release valve 21 and the like are enlarged even when the pressure of compressed air is increased, for example. It is possible to cope with it without any trouble, and the whole structure can be simplified to extend the durability and life.
[0064]
In each of the above embodiments, a two-stage air compressor including the low pressure side cylinder 5 and the high pressure side cylinder 10 has been described as an example. However, the present invention is not limited to this, and for example, a single cylinder is used. The present invention may be applied to a single-stage air compressor or a three-stage or more air compressor. Further, the present invention is not limited to a reciprocating type air compressor, and can be applied to, for example, a rocking piston type, rotary type or scroll type air compressor.
[0065]
【The invention's effect】
  As described above in detail, according to the present invention, as described in claim 1, the first and second discharge chambers and the compression chamber are provided in the compressor body, and these discharge chambers are provided in the first and first chambers with respect to the compression chamber. The two discharge valves are opened and closed independently of each other, and one of the discharge chambers is connected to an air tank, and the other discharge chamber isAway from the conduitSince it is configured to connect to the valve means, the valve means is opened by the valve drive means during no-load operation, thereby opening the other discharge chamber to the atmosphere and reducing the pressure in the compression chamber to atmospheric pressure. The load on the compressor body and the drive source can be automatically reduced. Then, the pressure from the air tank acts on the discharge valve on the one discharge chamber side, so that the discharge valve can be held in a closed state, and the compressed air stored in the air tank is not in a no-load operation. It can be surely prevented from leaking outside.
[0066]
Therefore, without using a check valve or the like, for example, by opening the second discharge chamber side to the atmosphere, no-load operation can be easily performed, and durability and reliability can be improved. For example, even when applied to a multi-stage air compressor, there is no need to provide an unload mechanism for each cylinder, the number of parts can be reduced and workability during assembly can be improved, and the overall structure can be simplified. And can extend durability and life.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a two-stage air compressor according to an embodiment of the present invention.
FIG. 2 is an overall configuration diagram of a load reducing device showing a high pressure side cylinder and a cylinder head in FIG.
FIG. 3 is an enlarged longitudinal sectional view showing a release valve in FIG. 2;
4 is a longitudinal sectional view similar to FIG. 3, showing the release valve when it is opened. FIG.
[Explanation of symbols]
1 Compressor body
2 Crankcase
3 Crankshaft
5 Low pressure side cylinder
6,11 piston
8,13 Cylinder head
9 Communication piping
10 High pressure side cylinder
15 Suction valve
16 First discharge valve
17 Second discharge valve
18 Electric motor (drive source)
19 Air tank
21 Release valve (valve means)
22 Unloading conduit
23 Valve housing
24 Pilot pressure chamber
27 Open air room
28 Silencer filter
29 Stepped piston
30 Disc
33 Solenoid valve (valve drive means)
A, B compression chamber
C Suction chamber
D First discharge chamber
E Second discharge chamber

Claims (2)

First and second discharge chambers having at least a compression chamber and first and second discharge chambers, and opened and closed independently from each other between the first and second discharge chambers and the compression chamber. A compressor body provided with a valve;
A drive source provided in the compressor body for driving the compressor body to generate compressed air in the compression chamber;
An air tank that is connected to one of the discharge chambers of the compressor body and stores compressed air discharged from the compression chamber through the one discharge chamber;
Said compressor being connected with the other discharge chamber position away through the conduit against the body, normally keeping the other discharge chamber by closing the high pressure, the other to open at the time of no-load operation Valve means for opening the discharge chamber to the atmosphere;
An air compressor load reducing device comprising valve driving means for opening and closing the valve means. The compressor body is a multistage compressor body having a low pressure side compression chamber and a high pressure side compression chamber, and the valve means is disposed on the high pressure side compression chamber side of the compressor body. The load reducing device for an air compressor according to claim 1, which is configured.

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