JPH0315681A - Pressure air supply device - Google Patents

Abstract

PURPOSE:To shorten a manhour requirement of initial air supply so as to extend a normal operating period, by using an air compressor having a plurality of cylinders and operating all cylinders at the time of initial air supply into an air reservoir, and operating only a part of the cylinders after the initial air supply. CONSTITUTION:Compressed air ejected from an air compressor C driven by an electric motor M flows to be stored into an air reservoir RES through a check valve CHV, while being supplied to an air compressed device. And a high pressure governor CMGH, has the electric driven motor M stopped when pressure in the air reservoir RES reaches a ceiling value, and has it started when the pressure reaches a lower limited value. In such a device, a low pressure governor CMGL is provided aside thereof, so that when pressure in the air reservoir RES rises up to a low limited value, an unload command is outputted to the unload mechanism of a part of cylinders in the air compressor C. And when the pressure decreases to the lowest limited value than the lower limited value, the output of the unload command is stopped.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a compressed air source device, particularly to prevent emulsification of lubricating oil due to leakage of compressed air from a piston ring of an air compressor into a crank chamber. Regarding.

[Conventional technology]

Figure 5 is a basic circuit diagram generally used in conventional pressure air source devices (Reference, Utility Model Application No. 62-1036
No. 60 and Japanese Unexamined Patent Publication No. 63-3583 (although they are not exactly the same, they are basically the same). In the figure, M is an electric motor, C is an air compressor, CHV is a check valve, RES is an air reservoir,
CMG is a pressure regulator, and CMK is a magnetic contactor. That is, power is supplied to the electric motor M through the electromagnetic contactor CMK, the air compressor C is driven by the electric motor M, and the pressurized air discharged from the air compressor C flows into the air reservoir RES through the check valve CHV and is accumulated in the load. Supply to pneumatic equipment. In addition, the pressure of the air reservoir RES is detected by the pressure regulator CMG,
When the upper limit set pressure is reached, the contact of the pressure regulator CMG turns off, demagnetizes the excitation winding of the magnetic contactor CMK, and activates the magnetic contactor C.
Cut off MK. Therefore, the electric motor M and the air compressor C stop. When the pressure in the air reservoir RES falls to the lower limit set value, the contact of the pressure regulator CMG turns on and the magnetic contactor CM
K is turned on, and the electric motor M and air compressor C are started up. Therefore, the pressure in the air reservoir RES is regulated to a value that is greater than or equal to the lower limit setting value and less than the upper limit setting value.

(Problem to be solved by the invention) When the capacity of the air reservoir RES is large, at the start of work, the air reservoir RE
It takes time to raise the pressure of S to a predetermined pressure. As a result, the start of work will be delayed.

Therefore, large capacity air compressors are employed.

However, when the pressure of the air reservoir RES reaches a predetermined pressure and the air is actually consumed by the pneumatic equipment, if the air consumption is small, the operating rate becomes extremely low, and as a result, the air compressor C As the temperature inside the crank chamber becomes lower, the water vapor in the compressed air that leaks from the piston ring is exposed in the crank chamber and precipitates moisture, causing the problem that the lubricating oil becomes emulsified. [Means for solving the problem] The problem mentioned above is that there is a large difference between the capacity of the air compressor required at the start of work and the capacity of the air compressor required when using normal pneumatic equipment. arise for the sake of Therefore, in the present invention, the temperature in the crank chamber is increased by increasing the operating rate of the air compressor during normal operation, thereby preventing the compressed air leaking from the piston ring from being exposed. Specifically, (1) the air compressor in the conventional device has multiple cylinders. (2) An unloading mechanism is installed for each cylinder of the air compressor mentioned above. This unload mechanism opens the suction valve and unloads the cylinder when an unload command signal is input from a second pressure regulator, which will be described later. (3) Adding a second pressure regulator to the conventional device. When the pressure of the air reservoir RES rises to the lower limit set value of the first pressure regulator CMG in the conventional device, this second pressure regulator unloads the load to the partial unload mechanism in the aforementioned cylinder. When the command signal is output and the pressure drops to the lowest set value lower than the lower limit set value, the output of the unload command signal is stopped.

[Effect]

Assuming the above structure, at the start of work, the pressure of the air reservoir RES is
Since the unload command signal is not output from the second pressure regulator until the pressure rises and reaches the lower limit set value, the air compressor C is operated with all cylinders. Therefore, the air reservoir RE
Initial loading into S is possible. When the pressure rises and reaches the lower limit set value of the first pressure regulator CMG (the upper limit set value of the second pressure regulator), the second pressure regulator outputs a hair unload command signal from a part of the unloading mechanism. Therefore, the cylinder that received the unload command signal becomes unloaded (unloaded), and the air compressor C is operated only with the remaining air. As a result, compared to the conventional case where all cylinders were operated, the air reservoir R
The time it takes for the ES pressure to reach the upper limit value becomes longer, and the normal operation rate becomes higher. Therefore, the temperature inside the crank chamber becomes higher than before, and emulsification of lubricating oil due to exposure of compressed air can be prevented. When the pressure reaches the upper limit value, the electric motor M and the air compressor C are stopped by a stop command from the conventional first pressure regulator CMG. Thereafter, when the pressure decreases to the lower limit set value due to the use of the pneumatic equipment, the electric motor M and the air compressor start operating according to an operation command from the first pressure regulator CMG. At this point, the second pressure regulator continues to issue a partial unloading command to the unloading mechanism, so the air compressor C is operated only with the remaining cylinders as before. When the use of all pneumatic equipment is completed and the air reservoir RES is exhausted and the pressure drops to the lowest set value (lower limit set value of the second pressure regulator), an unload command signal from the second pressure regulator is sent. Output is cut off and the system is ready to operate on all cylinders at the next start. [Example] Figures 1 to 4 are configuration diagrams of this example, where Figure 1 is an air circuit diagram, Figure 2 (A) is an electrical main circuit diagram, and Figure 2 (B) is an electrical control circuit. Figure 3 shows the conversion relay C in Figure 2 (b).
Figure 4, an explanatory diagram of the MR, is a sectional view showing the unloading mechanism of the air compressor. In Figure 1, electric motor M, air compressor C
, check valve CHV, air reservoir RES, high pressure regulator CMGH
(Exactly the same as the pressure regulator CMG in Fig. 5), the parts that are constructed are the same parts as the conventional one in Fig. 5. The high pressure regulator CMG}I is a pressure switch having a hysteresis characteristic that turns off when the upper limit set pressure rises to 9 kg/cd and turns on when the lower limit set pressure drops to 8 kg/cd. The low pressure regulator CMGL and solenoid valves MV1 and MV2 are parts added according to the present invention. The low pressure regulator CMGL may also have the same structure as the conventional pressure regulator CMG, and has a pressure hysteresis characteristic that turns off when the upper limit set pressure rises to 8 kg/cd and turns on when the lower limit set pressure falls to 7 kg/cd. (Note that the high pressure regulator CMGH corresponds to the "first pressure regulator" in the claims column, and the low pressure regulator C?v4GL corresponds to the "second pressure regulator"). The solenoid valves MVl and MV2 are in the communicating position when energized and in the blocking position when not energized. When energized, the unloading mechanism shown in FIG. The external air command intake port 43 hair unload command is input. In Figure 4,
Reference numeral 36 denotes a cylinder body constituting one cylinder of the air compressor C. A cylinder body 37 is formed inside the cylinder body, and a piston (not shown) rises from below to compress the air in the cylinder interior 37. By descending, the inside of the cylinder 37 is made thinner. An outer valve seat 39 having a discharge hole 44 and a suction hole 46 is inserted into the upper part of the cylinder body 36, and a discharge valve 27 and a spring 29 are placed above the discharge hole 44, and a spring 30 and a spring 30 are placed above the suction hole 46. The suction valve 28 is placed, and an inner valve seat 38 having a discharge hole 45 and a suction hole 47 is placed thereon, and the outer valve seat 39 and the inner valve seat 38 are tightened with countersunk bolts 31 and nuts 32 to form the valve part. It consists of Above this valve part, a suction chamber 34,
A cylinder M40 having a discharge chamber 35 is attached, a suction chamber I21 is screwed into the cylinder lid part above the suction chamber 34, and a joint 42 is screwed into the upper part of the suction chamber lid 2l. The suction valve pusher 26 has a rod that reaches above the suction valve 28 through a hole provided in the inner valve seat 38, and is normally provided between the upper surface of the inner valve seat 38 and the lower surface of the suction valve pusher 26. The tip of the rod is not in contact with the suction valve 28 because it is pushed upward by the biasing force of the suction valve pusher spring 33, but when force is applied from above to the suction valve pusher 26, the rod pushes down the suction valve 28 and forces it. It is planned that the valve will be opened automatically. Further, the upper part of the suction valve pusher 26 is also rod-shaped, and the suction valve pusher rod 24 is inserted from the upper part via a spring 25 so as to be slidable in the vertical direction. It is stopped by the biasing force of the spring 25 so that it does not pop out upward. The suction valve push rod 24 is
When a force is applied from above by the suction valve holding valve 22 via the pressure stop valve 23, it is pushed down. Suction valve holding valve 2
2 receives the unload command pressurized air (arrow A) flowing from above through the external air command intake port 43 of the joint 42, and is pushed downward by the air pressure. With the above precautions, under normal conditions when no unload command is received,
When a piston (not shown) descends inside the cylinder 37, the inside of the cylinder 37 becomes thin and the air pressure becomes lower than that of the suction chamber 34. As a result, the suction valve 28 is pushed open against the biasing force of the spring 30, and air is sucked into the cylinder interior 37 from the suction chamber 34 through the suction holes 47 and 46 (path indicated by arrow C). Next, when the piston rises, the inside of the cylinder 37
The air is compressed and the pressure inside the cylinder 37 is increased to the discharge chamber 35.
pressure becomes higher than that of As a result, the discharge valve 27
9 is pushed open against the urging force of 9, and the discharge chamber 35 is opened from the cylinder interior 37 through the discharge holes 44 and 45 (route indicated by arrow B).
Pressurized air is discharged to. Normally, suction and discharge are performed automatically in this way, and the air compressor IC is operated under load. In this state, when pressurized air for an unload command flows in from the command intake port 43 (arrow A), air pressure acts on the suction valve presser valve 22 from above through the passage in the joint 42, and the suction valve presser valve Press down on 22. When the suction valve presser valve 22 is pushed down, the pressure stop valve 23 and the suction valve push rod 24 are pushed down and the spring 25 is compressed. Therefore, the suction valve pusher 26 is pushed down, and its rod pushes down the suction valve 28 to forcibly open it. Therefore, even if the piston moves up, the air inside the cylinder 37 escapes to the suction chamber 34 through the suction holes 46, 47, so that the cylinder is operated under no load.

In FIG. 2, the conversion relay CMR is switched alternately each time the excitation coil is excited. In Fig. 3, when the coil 3 is energized, the movable core 4 moves upward (in the direction of the arrow), so the lever 2 is pushed down against the return spring 1, and the roller 12 attached to the tip of the lever 2 rotates the lever 2. The top 5 moves to the right in order to push the slope l3 of the top 5 downward.

Therefore, the conversion spring 6, which had been tilting the top 5 to the right, moves to the left side of the top 5, and tilts the top 5 to the left as shown in the figure on the right. As a result, the movable contact 8 moves from the right fixed contact 9 side to the left side and switches to the left fixed contact 7. When the excitation coil is demagnetized and then re-energized, roller l2 moves to top 5.
In order to push the right side of the inclined portion l3 downward, the top 5 moves to the left, and the top 5 tilts to the right as shown in the figure on the left. As a result, the movable contact 8 is switched to the right fixed contact 9 side. In Figure 2, each time conversion relay CMR is energized, its contacts alternately switch to the right and left, so 't
ifi contactors CMK1 and CMK2 are switched on and off in exchange. The operation of this embodiment, which has the above structure, will be explained. First, when starting work, it is necessary to initially fill the air reservoir RES with a large amount of air. When the main circuit and control circuit breakers are turned on, the pressure in the air reservoir RES is still low, so the high pressure regulator CMG
Both H and low pressure regulator CMGL are on. As a result, the auxiliary relay CMLR is energized, its normally open contact CMLR is turned on, and the t magnetic contactors CMKI, CMK2
are both turned on, electric motor M starts, and air compressor C
begins operation. At this time, the electromagnetic contactor CMKI,C
The normally closed contacts CMKI and CMK2 of MK2 are turned off,
Both solenoid valves MVI and MV2 are de-energized and in the blocked position. Therefore, no unload command is issued, and both the first and second cylinders are in a loaded state and air compression I! C is driven. As a result, the pressure in the air reservoir RES increases without requiring a long time. When the pressure of the air reservoir RES reaches the upper limit set value of 8 kg/c4 of the low pressure regulator CMGL, the low pressure regulator C
MGL is turned off. As a result, auxiliary relay CMLR is demagnetized and its normally open contact CMLR is turned off. At this point, the initial charging operation ends and the normal operation begins. At this time,
The high voltage regulator CMGH continues to be on, and the conversion relay CMR is on either the left or right side. Now, the conversion relay CMR is connected to the magnetic contactor CMK as shown in the diagram.
If it is turned on to the Z side, the electromagnetic contactor CMK2 continues to be in the closed state, and the electric motor M and the pneumatic machine C are in the operating state. At this time, the other electromagnetic contactor CMK1 is cut off, so its normally closed contact CMK1 is turned on, and the electromagnetic valve M
VI is energized. As a result, the solenoid valve MVI becomes in the communicating position, and the pressurized air in the air reservoir RES is supplied to the external air command intake port 43 (FIG. 4) of the air compressor C as an unload command. Therefore, the suction valve presser valve 22, the pressure stop valve 23, the suction valve push rod 24, the spring 25, the suction valve pusher 26
is lowered, the suction valve 28 is forcibly opened, and the first cylinder becomes unloaded. That is, the air compressor C is operated only on the second cylinder. Therefore, the time required for the high pressure regulator CMGH to reach the upper limit set value of 9 kg/cd is twice as long as in the case of conventional operation with all cylinders, and as the engine continues to operate during this time, the temperature of the crank chamber decreases. This prevents compressed air from being exposed. When the pressure of the air reservoir RES reaches the upper limit set value of 9 kg/c1M,
The high voltage regulator CMGH is also turned off, and the magnetic contactor CMK2
Also, the electric motor M and the air compressor C are stopped.

At this time, since both the electromagnetic contactors CMKI and CMK2 are in the cutoff state, these normally closed contacts CMKI and CMK2 are turned on. As a result, the conversion relay CMR is excited, and its contact is switched from the electromagnetic contactor CMK2 side to the CMKI side, and the next time it will be operated with CMK1. When the pneumatic equipment that is the load is used and the pressure of the air reservoir R E S falls to the lower limit set value 8 kg/C1a, the high pressure regulator CM
The GH is turned on, the electromagnetic contactor CMK1 is turned on, and the electric motor M and the air compressor C are operated by CMK1. At this time, the electromagnetic valve MV2 is excited, so the second cylinder is unloaded, and only the first cylinder is operated until it reaches 9 kg/cd. That is, in this embodiment, during normal operation, the first cylinder and the second cylinder are operated alternately using the conversion relay CMR so that the wear of each cylinder is uniform. At the end of the day's use, the pressure in the air reservoir RES is 7 kg/cJ, the lower limit set value of the low pressure regulator CMGL (in the claims, it is referred to as the "lowest limit set value" to distinguish it from the lower limit set value of the high pressure regulator). When the pressure drops to this level, the low pressure regulator CMGL is turned on to prepare for initial charging at the next start of work. As described above, in this embodiment, two cylinders are alternately switched and used, but this may be fixed to either cylinder, or an air compressor with three or more cylinders may be used. good. [Effect of the invention] The present invention uses an air compressor having a plurality of cylinders,
All cylinders are operated when initially filling the air reservoir, and only some of the cylinders are operated after initial filling, so initial filling does not take a long time, and the operation during regular use is shorter than before. The present invention provides excellent effects in that the time is increased, the operating rate is increased, the temperature drop in the crank chamber of the air compressor is reduced, and emulsification of lubricating oil due to exposure of compressed air can be prevented. Incidentally, as an alternative to the present invention, a plurality of sets of electric motors and air compressors are used,
It is conceivable to operate all the sets when it is first loaded, and only some sets during regular use, but in this case, there will be multiple electric motors and air compressors, so it will be difficult in terms of space, weight, and cost. , the present invention is more advantageous. It is also possible to solve the problem by controlling the rotation speed of the electric motor using inverter control or the like, but in this case as well, the present invention is more advantageous in terms of noise, power consumption, cost, etc. due to inverter control.

[Brief explanation of the drawing]

1 to 4 are structural diagrams of an embodiment according to the present invention.
The figure is an air circuit diagram, Figure 2 (a) is an electrical main circuit diagram, and the same figure (
b) is an electric control circuit diagram, Fig. 3 is an explanatory diagram of the conversion relay CMR in Fig. 2 (b), Fig. 4 is a sectional view showing the unloading mechanism of the air compressor, and Fig. 5 is a conventional pressure It is a basic circuit configuration diagram generally used in air source devices. M...Electric motor C...Air compressor CHV...Check valve RES...Air reservoir example 9 kg/cj...Upper limit set value Example example 8 kg/cd...Lower limit set value Example 7 kg/d・
...Lowest limit set value CMGH...First pressure regulator CMGL...Second pressure regulator 28...Suction valve

Claims (1)

[Claims] (1) An air compressor driven by an electric motor, an air reservoir in which pressurized air discharged from the air compressor flows in through a check valve, accumulates pressure, and supplies it to pneumatic equipment; A first pressure regulator that stops the electric motor when the pressure rises to an upper limit set value and starts and operates the electric motor when the pressure decreases to the lower limit set value, the air compressor is connected to a plurality of cylinders. In addition, the second part below
An unload mechanism is provided for each cylinder to open the suction valve and unload that cylinder when an unload command signal is input from the pressure regulator, and further, the pressure in the air reservoir reaches the lower limit setting value. when the pressure has increased, outputs an unload command signal to the unload mechanism of a part of the cylinder, and stops outputting the unload command signal when the pressure decreases to a lower limit set value lower than the lower limit set value. Pressure air source device equipped with two pressure regulators.