JPH04347382A - Pump discharge pressure controller - Google Patents

Abstract

PURPOSE:To provide a pump discharge pressure controller that controls a hydraulic motor, driving a fan constituting an engine cooling system, stably by means of a hydraulic pump being driven by, for example, an internal combustion engine. CONSTITUTION:A discharge fluid out of a hydraulic pump 11 driven by an internal combustion engine is fed to a hydraulic motor 14, and a pilot fluid circuit 18 is formed in parallel with this hydraulic motor 14. In addition, a throttle mechanism 20 and a hydraulic control valve 19 are installed in this hydraulic circuit 18 in series, while an upstream pressure port 244 and a downstream pressure port 245 are derived each from both upstream and downstream sides of this throttle mechanism 20, and a four-way valve 24 is controlled to be selected by a pressure differential between both these ports 244 and 245. In succession, a cam ring 111 setting a capacity of the hydraulic pump 11 by means of output out of this four-way valve 24 is controlled to be displaced, through which constant operating pressure is made so as to act on the hydraulic motor 14.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a cooling device installed in, for example, an automobile equipped with an internal combustion engine.
In particular, the present invention relates to a discharge pressure control device for a pump that is equipped with a load operated by fluid pressure, such as a hydraulic motor, and supplies working fluid to the load.

0002

[Background Art] Cooling systems installed in automobiles, etc. use fans to generate and supply cooling air to a radiator that circulates cooling water for an internal combustion engine, and a condenser unit that circulates refrigerant of an air conditioner. The structure is as follows. Means for driving this cooling fan include means for directly driving it by an internal combustion engine, as well as a hydraulic cooling system that supplies oil discharged from a hydraulic pump to a hydraulic motor and drives the cooling fan using the hydraulic motor. exist.

[0003] As a cooling system that utilizes fluid pressure, specifically oil pressure, a hydraulic drive device disclosed in, for example, Japanese Utility Model Application Publication No. 53-140827 is known. FIG. 7 shows the configuration of a control device using such hydraulic pressure. Oil discharged from a fixed capacity hydraulic pump 51 is supplied to a hydraulic motor 53 via a hydraulic circuit 52, and the hydraulic motor 53 The cooling fan 54 is driven to rotate. The cooling air generated by this cooling fan 54 is
A radiator 55 through which cooling water for the internal combustion engine is circulated, and a condenser 56 through which refrigerant for the air conditioner is circulated are supplied.

The hydraulic motor 53 is provided with a hydraulic circuit 57 in parallel, and this hydraulic circuit 57 is provided with a pressure control valve 58. By controlling the hydraulic control valve 58, the amount of oil flowing into the hydraulic circuit 57 is controlled. controlled by a hydraulic motor 53
The hydraulic pressure supplied to the engine is variably controlled.

That is, the hydraulic pressure supplied to the hydraulic motor 53 is controlled by the hydraulic control valve 58, and its rotation speed,
That is, the rotational speed of the cooling fan 54 is controlled to set the cooling capacity, and this hydraulic control valve 58 is controlled by an electronic control unit (ECU) 59. This ECU
59 is supplied with a detection signal from a water temperature sensor 60 set in the radiator 55, as well as an on/off signal from an air conditioner 61 mounted on this vehicle, and the pressure is adjusted according to the required cooling capacity. The opening degree of the control valve 28 is controlled.

In the device configured in this way, the hydraulic pump 51 always discharges oil corresponding to the maximum required amount, and the surplus flow rate of oil with respect to the amount of oil required by the hydraulic motor 53 is It is discarded to the drain side via the pressure control valve 28. Therefore, power loss is large.

FIG. 8 shows the relationship between the flow rate Q and the rotational speed Np of the hydraulic pump 51. The pump 51 has a fixed capacity, and the discharge capacity as shown by Gc is set in accordance with the rotational speed. If the flow rate required by the load is a in this diagram
1 and a2, the required flow rates of the hydraulic pump 53 are Qr1 and Qr2, and the amounts of oil shown as Ql1 and Ql2 are discarded, respectively.

[0008]

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and is aimed at controlling a load such as a hydraulic motor using fluid pressure discharged from a pump that generates working fluid pressure such as hydraulic pressure. In this case, fluid pressure control corresponding to the flow rate required by this load can be performed smoothly, and in particular, the generation of unnecessary surplus flow can be sufficiently reduced to improve economic efficiency, such as internal combustion for automobiles. It is an object of the present invention to provide a discharge pressure control device for a pump that constitutes a cooling device for an engine.

[0009]

[Means for Solving the Problems] A pump discharge pressure control device according to the present invention includes a variable displacement pump whose discharge capacity for pumping working fluid is controlled, and the output fluid from this pump is, for example, a hydraulic motor. Supplied to a load consisting of: A pilot fluid circuit with a throttling mechanism is formed in parallel with the fluid circuit of this load, and a pressure control valve is set in this pilot fluid circuit. The pressure difference between the upstream and downstream sides of the throttling mechanism of the pilot fluid circuit is detected, and the discharge capacity of the pump is controlled in accordance with the set pressure of the pressure control valve.

0010

[Operation] In the discharge pressure control device configured in this way, basically, by controlling the pressure of the pressure control valve set in the pilot fluid circuit, the working fluid corresponding to the required amount is supplied to the load. will be supplied. In this case, the surplus flow rate flowing into the pilot fluid circuit appears in the pressure difference before and after the throttling mechanism provided in the pilot fluid circuit, and when this pressure difference is large, the discharge capacity of the pump is controlled to decrease. That is, fluid pressure control for the load is smoothly executed, and in a state where the required fluid amount is reduced, the discharge capacity of the pump is reduced, and, for example, an efficient internal combustion engine cooling device is constructed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a cooling system for an internal combustion engine, in which a hydraulic pump 11 is driven by an internal combustion engine (not shown) and is constituted by a vane type variable displacement pump. This pump 11 sucks up oil set in a reservoir 12 and discharges it to a hydraulic circuit 13.The oil sent to this hydraulic circuit 13 is configured, for example, by a gear type, vane type, piston type, etc. is supplied to the hydraulic motor 14. The oil that has passed through the hydraulic motor 14 is returned to the reservoir 12.

A hydraulic motor 14 constituting a load to which this hydraulic pressure is supplied rotates a cooling fan 15 . On the upstream side of the cooling air generated by the cooling fan 15, there is a radiator 16 through which cooling water for the internal combustion engine is circulated.
A condenser 17 through which the refrigerant of the cooling system mounted on the vehicle is circulated is arranged in series, and a fan 15 is arranged in series.
It is designed to be cooled by the cooling air generated by the

A pilot fluid circuit 18 is provided in parallel with the hydraulic circuit of the hydraulic motor 14. A pressure control valve 19 is installed in this pilot fluid circuit 18 to variably control the pressure in the pilot fluid circuit 18, and the pressure is supplied to the hydraulic motor 14 almost in proportion to the pressure in this pilot fluid circuit 18. The flow rate is controlled.

The pilot fluid passage 18 is further provided with a throttle mechanism 20, and the oil that has passed through the throttle mechanism 20 is supplied to the pressure control valve 19. A pressure difference with the downstream side is generated in accordance with the flow rate of oil passing through this pilot fluid circuit 18.

Here, the solenoid 191 that controls the pressure control valve 19 is controlled by the ECU 21, and the ECU 21 receives a detection signal from a water temperature sensor 22 set in the radiator 16, and also receives a detection signal from the air conditioner 23.
On/off signals are supplied, and the pressure of oil flowing through the pressure control valve 19 is controlled by commands from the ECU 21, and the rotational speed of the hydraulic motor 14 is variably controlled in accordance with the required cooling capacity. There is.

The capacity of the hydraulic pump 11 is the same as that of the cam ring 11.
It is configured to be variably controlled by an amount of eccentricity of 1. The amount of eccentricity of this cam ring 111 is determined by the displacement control piston 1
12 and 113, and the positions of the pistons 112 and 113 are controlled by their back pressures, respectively. Here, the piston 112 is set to act in a direction to increase the amount of eccentricity of the cam ring 111, and the piston 113 is set to act in a direction to decrease the amount of eccentricity.

The back pressure of the pistons 112 and 113 is set by hydraulic pressure supplied from ports 114 and 115, and the pressures of these ports 114 and 115 are controlled by a four-way valve 24.

The four-way valve 24 is supplied with the differential pressure through an upstream pressure port 244 communicating with the upstream side of the throttling mechanism 20 and a downstream pressure port 245 communicating with the downstream side thereof. Which of the ports 114 and 115 is communicated with the high pressure port 241 and the drain pressure port 242 is controlled by the balance between the high pressure port 241 and the spring 243.

In the device configured in this way, the ECU
21, when the rotation speed of the hydraulic motor 14 is controlled to be constant and stable, the variable displacement hydraulic pump 1
Assume that the rotation speed of the drive shaft No. 1 fluctuates.

In this state, when the rotational speed of the hydraulic pump 11 increases, the discharge amount of the pump 11 increases in accordance with the increased rotational speed. Therefore, pilot fluid circuit 18
The amount of oil flowing through the throttle mechanism 20 increases, and the differential pressure across the throttle mechanism 20 increases.

That is, the force generated by the pressure supplied to the four-way valve 24 from the upstream pressure port 244 is equal to the force generated by the downstream pressure port 245 and the spring 2
43, the high pressure port 241 is connected to port 115 and the drain pressure port 242 is connected to port 1.
14, respectively. Therefore, the back pressure of the displacement control piston 113 increases, and the cam ring 111 is displaced in a direction that reduces the displacement of the pump 11.

Although the discharge capacity of the pump 11 is reduced by such control, if the discharge capacity decreases too much and the hydraulic motor 14 cannot rotate at a predetermined rotational speed, the pilot fluid circuit 18 flow rate decreases. In such a state, the differential pressure across the throttle mechanism 20 decreases, and the four-way valve 24 is switched to open the high pressure port 24.
1 is brought into communication with port 112, and the discharge capacity of pump 11 is controlled in the direction of increasing.

Therefore, for example, even if the rotational speed of the internal combustion engine that drives the pump 11 is not constant and the rotational speed of the pump 11 fluctuates, the rotational speed of the hydraulic motor 14 is kept constant. The discharge capacity of No. 11 is now variably controlled.

Here, the control of the rotational speed of the hydraulic motor 14, that is, the rotational speed control of the cooling fan 15, is controlled based on, for example, the state of the on/off switch of the air conditioner 23, the temperature detected from the water temperature sensor 22 of the radiator 16, etc. EC
It is determined by U21, and the drive current to the solenoid 191 of the pressure control valve 24 is controlled based on the result of the determination.

For example, assuming that the heat load on the internal combustion engine increases and it becomes necessary to increase the rotational speed of the cooling fan 15, the ECU 21 controls the solenoid 19 to increase the set pressure of the pressure control valve 24. Controls drive current.

Increasing the set pressure of the pressure control valve 24 means that the pressure at the downstream pressure port 245 on the downstream side of the throttle mechanism 20 increases, and the differential pressure across the throttle mechanism 20 decreases. Therefore, the force generated by the pressure supplied to the four-way valve 24 from the downstream pressure port 245 and the force of the spring 243 are transferred to the upstream pressure port 245.
the force generated by the pressure of the high pressure port 241
is connected to port 114, and drain pressure port 242 is connected to port 115. Therefore, the back pressure of the displacement control piston 112 increases, and the cam ring 1
11 is displaced in a direction that increases the capacity of pump 11.

[0027] Through such control, the discharge capacity of the pump 11 is increased, and the flow rate supplied to the hydraulic motor 14 is increased.
Although the rotation speed of the cooling fan 15 is increased,
If the discharge capacity increases too much and the number of revolutions of the hydraulic motor 14 exceeds a predetermined value, the flow rate of the pilot hydraulic circuit 18 increases and the differential pressure across the throttle mechanism 20 increases.

Therefore, in this state, the four-way valve 24 is switched so that the high pressure port 241 is communicated with the port 113, and the discharge capacity of the pump 11 is controlled to decrease.

By controlling the pressure control valve 24 of the pilot hydraulic circuit 18 in this manner, the hydraulic motor 14
The flow rate of fluid supplied to the hydraulic motor 1 is controlled.
The rotation speed of the cooling fan 15 driven by the cooling fan 4 is controlled.

FIG. 2 shows an example of the control pattern. When the air conditioner device 23 is turned off, the cooling water temperature in the radiator 17 is supplied to the solenoid 191 of the pressure control valve 19 from T1 to T2. The drive current I is increased proportionally. That is, the flow rate of the pressure control valve 19 is proportionally reduced, and the rotation speed of the hydraulic motor 14, that is, the cooling fan 15, is increased in proportion to the water temperature in the radiator 17.

When the water temperature of the radiator 16 is below temperature T1, the drive current of the solenoid 191 is set to the minimum current value Imin, and when the water temperature exceeds T2, the drive current of the hydraulic motor 14 is set to Imax.
The rotation speed is constant.

Here, when the air conditioner 23 is operated with the switch on, the refrigerant is circulated to the condenser 17 and the heat load increases. Rotation speed (drive current I
min) is increased as shown by the dashed line in FIG.

In the above embodiment, a pair of pistons 112 are used to control the cam ring 111 of the hydraulic pump 11.
and 113 were used. However, this hydraulic pump 1
As shown in FIG. 3, the cam ring 111 that controls the displacement of the cam ring 111 can be configured to be controlled in displacement by a piston 112 and a spring 116 whose elastic force acts in the opposite direction to the piston 112 .

That is, the spring 114 constantly pushes the cam ring 111 toward the reduction side, and the piston 112
is operated against the force of this spring 116 , and a port 114 that applies back pressure to this piston 112 is supplied from the three-way valve 31 .

Specifically, when the oil flow rate in the pilot fluid circuit 18 increases and the pressure on the upstream side of the throttle mechanism 20 increases, the port 114 becomes the drain pressure port 242.
The cam ring 111 is displaced by the force of the spring 116 in a direction that reduces the discharge capacity. Conversely, when the flow rate of the pilot fluid circuit 18 is reduced, the port 114 is communicated with the high pressure port 241,
The cam ring 111 is displaced by the piston 112 against the spring 116, and the discharge capacity of the hydraulic pump 11 is increased.

FIG. 4 shows yet another embodiment, in which a filter 30 is provided in the pilot fluid circuit 18 instead of the throttle mechanism 20 in the embodiments shown in FIGS. 1 and 3. .

The filter 30 removes dust and contaminants from the fluid flowing into the pilot fluid circuit 18, protects the pressure control valve 19, and at the same time performs a throttling action on the pilot fluid circuit 18 similar to a throttling mechanism.

Furthermore, in this embodiment, the pressure control valve 1
9 and the drain pressure passage of the three-way valve 31 is connected to the hydraulic pump 11.
Therefore, the components within the system 28 surrounded by the dashed line can be integrated, and the device can be easily miniaturized.

FIG. 5 shows an example of the configuration of the hydraulic pump 11 used in FIGS. 3 and 4.
A cam ring 111, a rotor 101, and a plurality of vanes 1 are provided in a chamber constituted by the housing 10.
02 etc.

The rotor 101 includes a shaft 103, and is rotationally driven by an internal combustion engine (not shown) via the shaft 103. Further, the cam ring 111 is arranged to be swingable about a pin 104 fixed to the housing 10 as a fulcrum.

A discharge port 105 formed in the housing 10 is located between the axis of the pin 104 and the rotor 101.
They are arranged asymmetrically with respect to a center line 106 connecting the axes of , so that the left side in the figure is larger than the right side.

Therefore, a force acts on the cam ring 111 in the direction of reducing the amount of eccentricity that is approximately proportional to the discharge pressure, thereby assisting the action of the spring 116. Therefore, the set load of this spring 116 can be reduced, and its size can be reduced.

In the embodiments described above, the high pressure port 24 is connected to the upstream side of the throttle mechanism 20 set upstream of the pressure control valve 19 set in the pilot fluid circuit 18.
1 is provided, and a drain pressure port 242 is further communicated with the downstream side of the pressure control valve 19. However, the upstream pressure port 244 only needs to be connected to the upstream side of the throttle mechanism 20. For example, as shown in FIG. You may also do so.

Further, as shown in FIG. 6B, a pressure control valve 19 and a throttle mechanism 20 are arranged in sequence from the upstream side of the pilot fluid circuit 18, and a high pressure port 241 is arranged upstream of the pressure control valve 19. It is also possible to communicate with the drain pressure port 242 on the downstream side of the throttle mechanism 20.

[0045]

As described above, according to the pump discharge pressure control device according to the present invention, when controlling the working fluid for a load such as a hydraulic motor, the pressure in the pilot fluid circuit is controlled by the pressure control valve. The pressure control valve is controlled in accordance with the flow rate required by the load, and the flow rate of the working fluid relative to the load is stably controlled by controlling the pressure of the fluid flowing into the pilot fluid circuit.
In a state where the differential pressure across the throttling mechanism provided in the pilot fluid circuit increases or decreases, the displacement of the hydraulic pump is variably controlled in response to the pressure in the pilot fluid circuit. Therefore, even if a hydraulic pump is directly driven by an internal combustion engine to apply a constant fluid pressure to a load in an automobile cooling system, for example, the discharge volume cannot be controlled in accordance with the rotational speed of the hydraulic pump. executed to provide a stable working fluid to the load.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram illustrating a pump discharge pressure control device according to an embodiment of the present invention using a cooling device for an internal combustion engine as an example.

FIG. 2 is a diagram illustrating an aspect of flow rate control of a pilot fluid circuit.

FIG. 3 is a configuration diagram illustrating another embodiment of the invention.

FIG. 4 is a configuration diagram illustrating still another embodiment of the invention.

FIG. 5 is a diagram illustrating an example of the structure of a pump used in the device according to the present invention.

FIGS. 6A and 6B are configuration diagrams illustrating other embodiments of the present invention, respectively.

FIG. 7 is a configuration diagram showing another example of a conventional engine cooling device.

FIG. 8 is a diagram illustrating a surplus flow rate when load control is performed using a control valve.

[Explanation of symbols]

11...Hydraulic pump, 111...Cam ring, 112,
113... Piston (for capacity control), 114, 115
...Port, 14...Hydraulic motor, 15...Cooling fan, 1
6... Radiator, 17... Capacitor, 18... Pilot fluid circuit, 19... Pressure control valve, 20... Throttle mechanism, 21...
Electronic control unit, 24... Four-way valve, 241... High pressure port, 242... Drain pressure port, 31... Three-way valve.

Claims (1)

[Claims] 1. A variable displacement pump whose discharge capacity for pumping working fluid is controlled; The pump is supplied with the working fluid discharged from the pump, and is driven in accordance with the amount of the supplied working fluid. a load device; a pilot fluid circuit that is set in parallel to the load device and to which working fluid discharged from the pump is supplied separately from the fluid circuit to the load device; and a pilot fluid circuit provided in the pilot fluid circuit. comprising a throttle action mechanism, a pressure control valve that controls the pressure of the pilot fluid circuit, and a switching valve mechanism that detects fluid pressures before and after the throttle action mechanism and is controlled based on the pressure difference, A pump discharge pressure control device, characterized in that a discharge capacity of the pump is controlled in accordance with a set pressure of the pressure control valve.