JP4306914B2 - Compressor drive unit for refrigeration - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration compressor driving device for a refrigeration vehicle or the like.
[0002]
[Prior art]
Some refrigeration vehicles equipped with a refrigerator rotate a hydraulic motor with the discharge pressure of a hydraulic pump and operate a refrigeration compressor using the rotational force of the hydraulic motor.
There are two methods for driving the refrigeration compressor, which are a sub-engine method and a direct connection method.
The sub-engine system is a type in which a special engine is provided in addition to the main engine for driving, and a hydraulic pump is driven by this special engine.
The direct connection system is a type in which a traveling engine is directly connected to a hydraulic pump.
[0003]
In addition, since the constant discharge pump is used in both systems, the constant discharge pump always operates while the engine is running, the refrigeration compressor works, and the inside of the freezer continues to be cooled. Therefore, the inside of the freezer may be cooled more than necessary. To prevent this overcooling, the engine had to be turned off.
[0004]
[Problems to be solved by the invention]
In the case of the sub-engine system, since it is necessary to mount two engines on the refrigeration vehicle, the cost is very high compared to the case of one. In addition, since the engine is heavy and takes place, there is a problem that the maximum load capacity of the luggage for one freezer car is limited.
In the case of the direct connection method, the capacity of the refrigeration compressor is reduced during idling. In particular, recently, in response to the demand of society called no idling, the engine is often turned off while the vehicle is stopped. If the engine is turned off, the refrigeration compressor will also stop completely. That is, there was a problem that the refrigerator would not function when the engine was stopped.
[0005]
On the other hand, in both the sub-engine system and the direct connection system, the constant discharge pump always operates while the engine is running, so the refrigeration compressor works and the inside of the freezer continues to be cooled. And in order to prevent the inside of a freezer from being overcooled, the engine must be turned off, but in the direct connection system, the engine cannot be turned off during traveling. Therefore, when traveling for a long time, the inside of the freezer is cooled more than necessary.
Even in the sub-engine system, there is a problem that the operation becomes troublesome because the engine has to be started and turned off.
[0006]
The first object of the present invention is that the refrigeration compressor does not stop when the traveling engine is stopped, or the refrigeration compressor does not have a reduced ability during idling, and is driven at low cost. It is providing the compressor drive device for a vehicle.
The second object is to provide a refrigeration compressor driving device having a mechanism for adjusting the temperature in the refrigerator.
[0007]
[Means for Solving the Problems]
In this invention , a first pump and a second pump are connected in parallel to a hydraulic motor that rotates a compressor, a traveling engine is used as a drive source for the first pump, and an electric motor is used as a drive source for the second pump. The supply flow path of the first pump and the second pump is merged, and a shuttle valve is provided at the merge point to supply the discharge pressure of either the first pump or the second pump to the hydraulic motor. On the premise of a refrigeration compressor driving device, a shuttle valve provided at the junction and the hydraulic motor are connected via a throttle valve, and the discharge amounts of the first and second pumps are set to the differential pressure of the throttle valve. A regulator that controls the pressure to be kept constant, a pilot pump that rotates integrally with each of the first and second pumps, and a shuttle valve that selects a high discharge pressure of these pilot pumps A temperature sensor that measures the temperature in the refrigerator, a controller that receives a signal from the temperature sensor, a pilot control valve that opens and closes a pilot flow path according to the signal from the controller, and a stroke that is caused by opening and closing the pilot control valve. A pilot piston for controlling the opening of the valve, and when the temperature in the refrigerator is higher than the set temperature, the controller closes the pilot control valve, opens the throttle valve when the pilot piston does not stroke, and The hydraulic pressure from the first or second pump is supplied to the hydraulic motor as it is. On the other hand, when the temperature in the refrigerator is lower than the set temperature, the controller opens the pilot control valve, and the pilot piston strokes to throttle the throttle valve. To be supplied to the hydraulic motor Characterized in that the inhibiting configure pressure.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a first embodiment of the present invention.
In the first embodiment, two variable discharge pumps P1 and P2 are provided, one of the variable discharge pumps P1 is driven by an engine E for running the vehicle, and the other variable discharge pump P2 is related to the engine E. It is intended to be driven by a non-electric motor EM.
Then, the hydraulic motor M is driven by any one of the variable discharge pumps P1 or P2 so as to operate the compressor 1 for refrigeration.
[0009]
Each of the variable discharge pumps P1 and P2 is connected to upstream supply passages 2 and 3, and these upstream supply passages 2 and 3 are connected to downstream supply passages via a shuttle valve 4. 5 is communicated. A hydraulic motor M is connected to the downstream supply passage 5.
Therefore, when any one of the variable pumps P1 and P2 is driven, the discharged oil is selected by the shuttle valve 4 and supplied to the hydraulic motor M.
[0010]
A throttle valve 6 is provided in the downstream supply channel 5. The throttle valve 6 keeps the open position 6a in the illustrated normal state and keeps the throttle position 6b in the switching state.
The variable discharge pumps P1 and P2 control the discharge amount so as to keep the differential pressure before and after the throttle valve 6 constant, and the elements that control the discharge amount are regulators R1 and R2. The regulators R1 and R2 are composed of regulator valves 7 and 8 and control cylinders 9 and 10, respectively.
[0011]
The regulator valves 7 and 8 have one pilot chambers 7 a and 8 a communicated with the upstream side of the throttle valve 6 and the other pilot chambers 7 b and 8 b communicated with the downstream side of the throttle valve 6. The spring force of the springs 11 and 12 is applied to one of the pilot chambers 7 a and 8 a . Thus, the regulator valve 7, 8 and the total force of the spring force of the force acting on the pilot chamber 7 b, 8 b of the other hand, the acting force of the hand pilot chamber 7 a, 8 a of and springs 11 and 12 Keep a balanced position. In this balance position, the pressures in the pressure chambers 9a and 10a of the control cylinders 9 and 10 are controlled.
[0012]
The control cylinders 9 and 10 are provided with springs 13 and 14 in chambers 9b and 10b opposite to the pressure chambers 9a and 10a. Normally, the piston rods 9c and 10c contract by the action of the springs 13 and 14. I try to keep it in position.
When the piston rods 9c and 10c are in the contracted position, the tilt angles of the variable discharge pumps P1 and P2 are kept at the maximum, and the discharge amount is maximized. On the contrary, if the pressure in the pressure chambers 9a and 10a is increased and the piston rods 9c and 10c are extended, the discharge amounts of the variable discharge pumps P1 and P2 are decreased.
[0013]
The regulator valves 7 and 8 control the pressure in the pressure chambers 9a and 10a. That is, if the regulator valves 7 and 8 are at the left side position (A) in the drawing, the pressure chambers 9a and 10a are connected to the tank T, and the piston rods 9c and 10c are contracted. The chambers 9a and 10a are connected to the supply flow paths 2 and 3 to extend the piston rods 9c and 10c.
[0014]
The discharge amounts of the variable discharge pumps P1 and P2 as described above are determined depending on whether the throttle valve 6 is in the open position 6a or the throttle position 6b. That is, the regulator valves 7 and 8 control the discharge amounts of the variable discharge pumps P1 and P2 so as to keep the differential pressure before and after the throttle valve 6 at a pressure corresponding to the spring force of the springs 11 and 12, as described above. . Therefore, if the throttle valve 6 is in the open position 6a, the pump discharge amount increases, and if it is in the throttle position 6b, it decreases.
[0015]
The throttle valve 6 is set to the open position 6a or to the throttle position 6b by springs 15 and switching cylinders 16 provided on both sides of the throttle valve 6.
That is, the spring force of the spring 15 is applied to one side of the throttle valve 6, and the open position 6a shown in the figure is normally maintained by the action of this spring force. A switching cylinder 16 is provided on the other side of the throttle valve 6, and the thrust of the switching cylinder 16 switches the throttle valve 6 to the throttle position 6 b against the spring 15.
[0016]
The switching cylinder 16 is controlled by the pilot pressure of pilot pumps 17 and 18 that rotate integrally with the variable discharge pumps P1 and P2. Note that the discharge pressure of the pilot pumps 17 and 18 is also selected by the shuttle valve 23 to be high, and is guided to an electromagnetic control valve 19 described below.
The electromagnetic control valve 19 controlled by the output signal of the controller C is responsible for controlling whether or not the pilot pressure selected as described above is guided to the switching cylinder 16. The electromagnetic control valve 19 is a pressure reducing valve or an on / off valve, and controls the pilot pressure guided to the switching cylinder 16 in accordance with the output signal of the controller C.
[0017]
A controller C that controls the electromagnetic control valve 19 is connected to a temperature sensor 20 that detects the temperature in the refrigerator. If the temperature in the refrigerator is equal to or higher than the set temperature, the controller C controls the electromagnetic control valve 19 to maintain the pilot pressure supplied to the switching cylinder 16 at a low pressure. In this state, the spring force of the spring 15 with respect to the throttle valve 6 is set to be larger than the thrust of the switching cylinder 16. Therefore, the throttle valve 6 holds the open position 6 a by the spring force of the spring 16.
[0018]
Further, when the temperature in the freezer becomes equal to or lower than the set temperature, the temperature sensor 20 detects this, and the controller C operates the electromagnetic control valve 19 based on the detected temperature, and the pilot pressure guided to the switching cylinder 16. Is maintained at a high pressure. In this state, the thrust of the switching cylinder 16 is made larger than the spring force of the spring 15 with respect to the throttle valve 6. Therefore, the throttle valve 6 is switched to the throttle position 6 b by the thrust of the switching cylinder 16.
[0019]
Next, the operation of the first embodiment will be described.
In this compressor driving device, it is up to a person such as a driver to drive the variable pump P1 on the engine E side or the variable discharge pump P2 on the electric motor EM side. In other words, a driver or the like decides which one to select manually.
[0020]
If the variable discharge pump P1 is selected now, the pilot pump 17 is driven together with the variable discharge pump P1.
Then, the pressure oil discharged from the variable discharge pump P <b> 1 is guided to the downstream supply passage 5 via the shuttle valve 4. Since the shuttle valve 4 is provided at the confluence of the upstream supply flow paths 2 and 3, when either one of the variable discharge pumps P1 or P2 is driven, the discharge oil of the driven pump is automatically selected. Then, it is guided to the supply flow path 5.
The pressure oil guided to the downstream supply passage 5 in this way is supplied to the hydraulic motor M via the throttle valve 6 and operates the compressor 1 to cool the inside of the freezer.
[0021]
When pressure oil is supplied to the hydraulic motor M via the throttle valve 6 as described above, the pressure before and after the throttle valve 6 is guided to the pilot chambers 7a and 7b of the regulator valve 7 as pilot pressure. When the pilot pressure is introduced to the regulator valve 7 in this way, the regulator valve 7 is connected to the variable discharge pump P1 via the control cylinder 9 so that the differential pressure before and after the throttle valve 6 corresponds to the spring force of the spring 11. The amount of discharge is controlled.
[0022]
Therefore, if the throttle valve 6 is in the open position 6a, the discharge amount of the variable discharge pump P1 must be kept large in order to keep the differential pressure constant. However, if the throttle valve 6 is in the throttle position 6b, the discharge amount must be reduced.
If the temperature in the freezer is equal to or higher than the set temperature, i.e., when the temperature in the freezer needs to be further reduced, the electromagnetic control valve 19 reduces the pilot pressure led to the switching cylinder 16 based on the command from the controller C that has detected the temperature. Keep low.
[0023]
If the pilot pressure is low, the throttle valve 6 maintains the open position 6 a shown in the figure by the action of the spring 15. Therefore, as described above, the discharge amount of the variable discharge pump P1 is sufficiently secured, and the hydraulic motor M is fully rotated by the sufficient amount. When the hydraulic motor M is fully rotated, the compressor 1 is also fully rotated, so that the inside of the freezer is cooled.
[0024]
On the other hand, when the temperature in the freezer is equal to or lower than the set temperature, that is, when the inside of the freezer is too cold, the controller C that detects the temperature in the refrigerator via the temperature sensor 20 controls the electromagnetic control valve 19 to switch the switching cylinder. The pilot pressure led to 16 is increased. The thrust of the switching cylinder 19 generated by the increased pilot pressure overcomes the spring force of the spring 15 and switches the throttle valve 6 to the throttle position 6b.
When the throttle valve 6 is switched to the throttle position 6b, the regulator R1 operates as described above to reduce the discharge amount of the variable discharge pump P1.
[0025]
The throttle valve 6 is in the open position 6a when it is fully opened, and is in the throttle position 7b when the opening is minimum. The throttle valve 6 is opened depending on the balance of the force between the spring 15 and the switching cylinder 16. The degree changes continuously.
If the discharge amount of the variable discharge pump P1 decreases as described above, the rotation of the hydraulic motor M also decreases accordingly. If the opening degree of the throttle valve 6 at the throttle position 6b is sufficiently small, the hydraulic motor M can be kept almost in a stopped state.
[0026]
Moreover, what is necessary is just to drive the electric motor M when selecting the variable discharge pump P2. By driving the electric motor M, the pilot pump 18 is rotated together with the variable discharge pump P2.
The hydraulic motor M is driven by the rotation of the variable pump P2 and the pilot pump 18, and the regulator R2 is operated according to the temperature in the freezer. This is exactly the same as in the case of the variable discharge pump P1.
[0027]
As described above, according to the apparatus of the first embodiment, the driver decides whether to select the traveling engine E as the pump drive source or to select the electric motor EM unrelated to the engine. Can do.
Therefore, the inside of the freezer can be continuously cooled even when idling or when the engine is stopped. In addition, since the rotation of the hydraulic motor M can be controlled according to the temperature in the freezer, the inside of the refrigerator can always be kept at an appropriate temperature.
Furthermore, since the engine E and the electric motor EM are combined, it is possible to reduce the size and weight by the amount of the electric motor EM, for example, compared to the case where the traveling engine and the sub-engine are separately provided as in the prior art. become.
[0028]
FIG. 2 shows a second embodiment. In the second embodiment, the regulator valves of the regulators R1 and R2 of the first embodiment are made common. Since the other components are the same as those in the first embodiment, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.
In the second embodiment, only one regulator valve 7 of the first embodiment is used, and the control cylinders 9 and 10 are communicated with each other via the communication passage 21.
It is different from the first embodiment in that the pressure oil between the shuttle valve 4 and the throttle valve 6 is guided to the regulator valve 7. However, this is a natural consequence of the common use of the regulator valve 7, and is substantially the same as in the first embodiment.
[0029]
By connecting the control cylinders 9 and 10 through the communication passage 21 as described above, the regulator valve 7 for the control cylinders 9 and 10 can be shared. Since the regulator valve 7 can be shared in this way, the hydraulic device can be reduced in size and weight accordingly. As the hydraulic system is reduced in size and weight, a larger loading space and weight can be secured.
[0031]
【The invention's effect】
According to the apparatus of this invention, since the drive of the freezing compressor can be controlled according to the temperature in the freezer, the temperature in the freezer can be managed.
In addition, it is possible to select whether an engine or an electric motor is used to drive the refrigeration compressor. Therefore, the refrigerating capacity of the refrigerator can be maintained by driving the compressor with the electric motor even when the vehicle is stopped or idling.
The combined use of an engine and an electric motor is less expensive and takes less space than when two engines are driven.
[0032]
In addition, since the first pump and the second pump connected in parallel are provided with a shuttle valve at the junction, only the flow from one of the pumps is allowed. Moreover, the backflow to a mutual pump can be prevented.
Furthermore, since a pilot pump for guiding the pilot pressure to the pilot control valve is provided, the pilot control valve has a sufficiently reduced pressure compared to the case where the pilot pressure is led from the first and second pumps instead of the pilot pump. It is not necessary to have a function.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a first embodiment.
FIG. 2 is a circuit diagram of a second embodiment .
[Explanation of symbols]
P1 Variable discharge pump P2 Variable discharge pump E Engine EM Electric motor M Hydraulic motor 1 Refrigeration compressor 4 Shuttle valve 6 Throttle valve 6a Open position 6b Throttle position C Controller
17 Pilot pump
18 Pilot pump 19 Electromagnetic control valve 20 Temperature sensor
23 Shuttle valve

Claims (1)

A first pump and a second pump are connected in parallel to a hydraulic motor that rotates a compressor, a traveling engine is used as a drive source for the first pump, an electric motor is used as a drive source for the second pump , and the first pump Refrigeration compressor drive configured to supply the discharge pressure of either the first pump or the second pump to the hydraulic motor by merging the supply flow path between the first pump and the second pump and providing a shuttle valve at the junction In the apparatus, the shuttle valve provided at the junction and the hydraulic motor are connected via a throttle valve, and the discharge amount of the first and second pumps is kept constant at the differential pressure of the throttle valve. A regulator for controlling, a pilot pump that rotates integrally with each of the first and second pumps, a shuttle valve that selects a high discharge pressure of these pilot pumps, A temperature sensor that measures the degree of temperature, a controller that receives a signal from the temperature sensor, a pilot control valve that opens and closes the pilot flow path according to the signal of the controller, and a stroke that opens and closes by opening and closing the pilot control valve. When the temperature in the refrigerator is higher than the set temperature, the controller closes the pilot control valve and opens the throttle valve when the pilot piston does not stroke, and the first or second The hydraulic pressure from the pump is supplied to the hydraulic motor as it is.On the other hand, when the temperature in the refrigerator is lower than the set temperature, the controller opens the pilot control valve, and the pilot piston strokes to switch the throttle valve to the throttle position. Suppresses the hydraulic pressure supplied to the hydraulic motor Refrigeration compressors drive device was formed.

Images