JPH0434247Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydraulic system, for example, which is connected to an engine of an automobile or the like to operate a gear for driving a power steering device and a hydraulic motor for driving a cooling fan. The present invention relates to a hydraulic device applicable to a tandem pump device.

[Prior art] The configuration of the conventional tandem pump type hydraulic system is
As shown in the figure. This conventional hydraulic system includes an oil reservoir 100, a hydraulic pump 102 that receives oil from the oil reservoir 100 and sends out pressure oil through a flow rate control valve 101, and
a first hydraulic circuit A comprising a gear 103 for a power steering device which is driven by pressure oil from the oil reservoir 100 and discharges the oil into the oil reservoir 100; and a flow rate control valve which receives oil from the oil reservoir 100. Hydraulic pump 10 delivering pressure oil via 104
5, and a cooling fan driving hydraulic motor 106 that operates with pressure oil from the hydraulic pump 105 and discharges oil into the oil reservoir 100.

In the hydraulic system in the above-mentioned conventional technology, a first hydraulic circuit A that operates each hydraulic pump 102 and 105 and a second hydraulic circuit B are independent in terms of circuit configuration (however, the oil reservoir 100 may be shared). (Sometimes it has a different configuration.) The flow rate control valve 104 on the cooling fan drive side is equipped with an electromagnetic valve, and is designed to arbitrarily change the rotation speed of the cooling fan (see FIG. 4). Further, the controlled flow rate of the hydraulic pump 105 for driving the cooling fan is set such that 2 to 3 l/min of pressure oil is discharged in order to prevent heat generation inside the hydraulic pump 105 even when the radiator water temperature of the automobile is low.

[Problems to be Solved by the Invention] In the hydraulic system according to the above-mentioned conventional technology, the controlled flow rate of the hydraulic pump 102 that operates the drive gear 103 of the power steering device is maintained at a set value at room temperature. In cold weather, the resistance of the pipeline increases due to the increase in the viscosity of the oil, so the hydraulic pump 10
The internal pressure of 2 increases and energy loss occurs. That is, there was a problem in that the flow rate control valve 101 opened earlier than at room temperature, resulting in a decrease in the controlled flow rate. Furthermore, in cold weather, there is a problem in the relationship between the operating pressure of the power steering device and the steering wheel torque, in that the steering torque increases compared to at room temperature, and the steering characteristics deteriorate. Furthermore, even in cold weather, as mentioned above, the cooling fan rotates slowly to prevent heat generation inside the hydraulic pump 105, which has the disadvantage that the engine warm-up efficiency is hindered.

This invention solves the above problems,
The controlled flow rate of the hydraulic pump on the power steering device side is maintained at a flow level close to that at room temperature even in cold weather, eliminating the difference in steering characteristics between cold and room temperature, and eliminating unnecessary cooling fans in cold weather. It is an object of the present invention to provide a hydraulic device that can prevent rotation and improve the utilization efficiency of the discharge flow of a cooling fan side pump.

[Means for Solving the Problems] The hydraulic system of the present invention includes: an oil reservoir; a first hydraulic pump that receives oil from the oil reservoir and delivers pressure oil through a first flow control valve;
a first hydraulic actuator for power steering driven by pressure oil supplied from the first hydraulic pump and discharging oil into the oil reservoir; and a second hydraulic actuator receiving oil from the oil reservoir via a second flow control valve. a second hydraulic pump that delivers pressure oil; a second hydraulic actuation device that is driven by the pressure oil supplied from the second hydraulic pump and discharges the oil into the oil reservoir; and a second hydraulic actuator that is supplied to at least the first hydraulic pump. A temperature sensor that detects the temperature of oil is provided between the second hydraulic pump and the second hydraulic actuator, and the temperature sensor detects the temperature of the oil and controls the supply of pressure oil to the second hydraulic actuator.
It is characterized by comprising a hydraulic circuit switching valve that switches between the hydraulic operating device and the first hydraulic operating device via a bypass passage, and a control section that controls the hydraulic circuit switching valve based on input from the temperature sensor.

[Function] In the hydraulic system of the present invention, when the temperature of the oil detected by the temperature sensor is below a predetermined value, the control unit moves the hydraulic circuit switching valve to the first hydraulic actuating device side based on the input from the temperature sensor. acts to switch,
Pressure oil from the second hydraulically operated device is supplied to the first hydraulically operated device via the bypass passage. When the temperature of the oil is equal to or higher than a predetermined value, the hydraulic circuit switching valve is switched so that the pressure oil supplied from the second hydraulic pump is supplied only to the second hydraulic actuation device.

[Example] Hereinafter, a specific example in which the hydraulic system of the present invention is applied to a tandem pump type hydraulic system for automobiles will be described with reference to the drawings.

Figure 1 shows a circuit diagram of the hydraulic system according to this embodiment, and Figure 2 shows a graph showing the relationship between the rotation speed and the pressure oil supply system to the first hydraulic actuator for power steering in cold weather. , and a graph showing the same steering characteristics in cold weather is shown in FIG. 3.

As shown in FIG. 1, the hydraulic system according to this embodiment includes an oil reservoir 2, a first hydraulic pump 3,
A first hydraulic actuator 4 for power steering, a second hydraulic pump 5, a second hydraulic actuator 6 which is a hydraulic motor for driving a cooling fan, a temperature sensor 7 for detecting oil temperature, and a hydraulic circuit switching valve. 8 and a control section 9 as constituent elements.

The oil reservoir 2 is a tandem pump device 50
It has the function of supplying oil to the first hydraulic pump 3 and the second hydraulic pump 5 that make up the pump, and also functions as a tank to which used pressure oil is returned.

The first hydraulic pump 3 receives oil from the oil reservoir 2 through a suction passage 20 to its suction chamber (not shown), and receives pressure oil from its discharge chamber (not shown) through the first flow control valve 10 and the following components. It is sent to a first hydraulic actuator 4 for power steering, which will be described later. That is, a pressure difference is created before and after the first flow control valve 10 downstream of the first flow control valve 10.
0, a relief valve 1 that protects the first hydraulic pump 3 from an abnormal increase in the discharge side oil pressure.
3 and a lead-out passage 14 communicating with the first hydraulic actuator.
is connected to the circuit. A constant flow rate of pressure oil is supplied to the first hydraulic actuator 4 for power steering by the action of the first flow control valve 10 and the like, and the excess flow is drained into the suction chamber of the first hydraulic pump 3 through the branch passage 17. It is refluxed to the side.

The first hydraulic pump 3 has a rotor (not shown) mounted on a single drive shaft 16 that rotates in conjunction with the engine 15 of the automobile, and is driven to rotate simultaneously with the rotor (not shown) of the second hydraulic pump 5 . Although a vane pump is used as the first hydraulic pump 3 in this embodiment, the present invention is not limited to this.

The second hydraulic pump 5 receives oil from the oil reservoir 2 through a suction passage 30 to its suction chamber (not shown), and from its discharge chamber (not shown) to an electromagnetic flow control valve 18, which is a second flow control valve, and each of the following Pressure oil is supplied to a cooling fan drive hydraulic motor 6 (second hydraulic actuation device), which will be described later, through structural members.
Send to.

The electromagnetic flow control valve 18 includes an electromagnetic throttle 21 that continuously changes the opening degree of a throttle (not shown) built into the electromagnetic flow control valve 18, and the electromagnetic throttle 2.
Flow control valve 2 that operates according to the pressure difference before and after 1
It is composed of 2. A relief valve 23 is provided downstream of the electromagnetic flow control valve 18 and the electromagnetic throttle 21 to protect the second hydraulic pump 5 from an abnormal increase in the discharge side oil pressure. Pressure oil discharged from the second hydraulic pump 5 and passed through the electromagnetic flow control valve 18 and the electromagnetic throttle 21 is supplied to the cooling fan driving hydraulic motor 6 via the outlet passage 24. Further, a constant flow of pressure oil is supplied to the cooling fan driving hydraulic motor 6 by the action of an electromagnetic flow control valve 18 serving as a second flow control valve, and the excess flow is supplied to the second hydraulic pump 5 through a branch passage 27. It is refluxed to the suction chamber side. The cooling fan driving hydraulic motor 6 drives a cooling fan 26 attached to the tip of its drive shaft 25.

The temperature sensor 7 is attached to the housing 2a of the oil reservoir 2 and detects the temperature of the oil in the oil reservoir 2.

This temperature sensor 7 is connected to a control unit 9 along with a water temperature sensor 29 that detects the temperature of cooling water in the radiator 28.
It is connected to the. The control section 9 is further connected to an electromagnetic throttle 21 of the electromagnetic flow control valve 18 .

The electromagnetic direction switching valve 8 communicates a bypass passage 31 that connects the hydraulic circuit on the first hydraulic pump 3 side with the hydraulic circuit on the second hydraulic pump 5 side. By communicating or blocking this bypass passage 31, the first
Outlet passage 14 on hydraulic pump 3 side and 2 hydraulic pump 5
It acts to switch the flow of pressure oil to either side of the outlet passage 24.

The control unit 9 controls an electromagnetic direction switching valve 8 (hydraulic circuit switching control valve). Note that the bypass passage 31 is provided with a check valve 32 that allows pressure oil to flow only in the direction of the first hydraulic actuator 4 from the second hydraulic pump 5.

The operation of the hydraulic system of this embodiment will be explained below.

The control unit 9 receives detection signals from the temperature sensor 7 provided in the oil reservoir 2 and the water temperature sensor 29 provided in the radiator 28 . When the detection signal indicates a cold state (for example, below 0° C.), the control section 9 switches and sets the electromagnetic direction switching valve 8 to the state indicated by the reference numeral in FIG. Thereby, the discharge flow rate from the second hydraulic pump 5 that supplies pressure oil to the hydraulic motor 6 for driving the cooling fan is controlled via the bypass passage 31 to the hydraulic pressure on the side of the first hydraulic actuating device 4 for driving the power steering device. Supply to the circuit. Then, the assist characteristics of the first hydraulic actuating device 4 for driving the power steering device are set close to those at room temperature. At this time, due to the action of the check valve 32, the pressure oil from the second hydraulic pump 5 flows only in the direction of the first hydraulic actuator 4.

Next, when the temperature detected by the temperature sensor 7 and the water temperature sensor 29 is normal temperature, that fact is input from the control section 9 to the electromagnetic direction switching valve 8 . In this case, the electromagnetic direction switching valve 8 is switched to the state shown in FIG. The pressure oil does not flow in the direction of the first hydraulic actuator 4.

As described above, according to this embodiment, as shown in FIG. 2, in cold weather, the first hydraulic actuating device 4 side for the power steering device is configured to control the discharge flow rate from the first hydraulic pump 3 and the second hydraulic pressure. Pressure oil is supplied at a flow rate that is the sum of the discharge flow rate from the pump 5. As shown in Figure 2,
When it is cold, the electromagnetic flow control valve 18 opens earlier than when it is at room temperature, but by switching the electromagnetic direction switching valve 8, the flow is transferred from the hydraulic circuit side of the cooling fan drive hydraulic motor 6 to the power steering device drive gear 4. Since pressure oil is supplied, a constant flow of pressure oil flows on the power steering device drive gear 4 side. Therefore, the constant flow rate control range on the power steering device driving gear 4 side is expanded to the low speed side.

Also, in cold weather, the second
Since no pressure oil flows to the hydraulic actuation device 6, unnecessary rotation of the cooling fan as in the conventional case does not occur.

Furthermore, as shown in FIG. 3, it was confirmed that steering characteristics similar to those at room temperature could be obtained even in cold weather.

In this embodiment, the second hydraulic pump 5 is operated by the cooling fan driving hydraulic motor 6, but the second hydraulic pump 5 is not limited to this and may be used for other purposes.

Further, the first hydraulic pump 3 and the second hydraulic pump 5 may not be of a tandem pump type, but may be provided independently.

[Effects] According to the hydraulic system of the present invention, a temperature sensor that detects the temperature of oil, a control unit that receives input from this sensor, and a hydraulic circuit switching valve that switches the hydraulic circuit according to the input from the sensor are provided. As a result, even in cold weather, steering characteristics of the steering wheel can be obtained that are almost the same as those at room temperature. Moreover, unnecessary rotation of the cooling fan is prevented in cold weather, and the discharge flow from the second hydraulic pump side is effectively utilized. Furthermore, in cold weather, the viscosity of the oil increases, the pipe resistance increases, and the differential pressure increases, causing the flow rate control valve to open earlier than at room temperature. The discharge flow flows toward the hydraulic circuit for operating the power steering device. This allows the constant flow rate control range to be extended to the lower speed side.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the hydraulic circuit configuration of the hydraulic system of this embodiment. FIG. 2 is a graph showing the relationship between the flow rate of pressure oil supplied to the drive side of the power steering device and the rotational speed of the first hydraulic pump in cold weather. FIG. 3 is a graph showing the steering characteristics in cold weather. FIG. 4 is a diagram showing the configuration of a conventional hydraulic circuit. 2... Oil reservoir, 3... First hydraulic pump, 4... First actuating device, 5... Second hydraulic pump, 6... Second hydraulic actuating device, 7... Temperature sensor, 8... Electromagnetic direction Switching valve (hydraulic circuit switching valve),
9...Control unit, 31...Bypass passage, 32...
non-return valve.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) An oil reservoir, a first hydraulic pump that receives oil from the oil reservoir and sends out pressure oil through a first flow control valve, and supplies the oil from the first hydraulic pump. a first hydraulic actuator for power steering driven by the pressure oil supplied to the oil reservoir and discharging the oil into the oil reservoir; a hydraulic pump, a second hydraulic actuator driven by pressure oil supplied from the second hydraulic pump and discharging oil into the oil reservoir; and a temperature for detecting the temperature of at least the oil supplied to the first hydraulic pump. a sensor, the second hydraulic pump, and the second hydraulic pump;
a hydraulic circuit switching valve provided between the hydraulic actuating device and switching the supply of pressure oil to the second hydraulic actuating device and the first hydraulic actuating device via a bypass passage; A hydraulic device comprising: a control section that controls a hydraulic circuit switching valve. (2) The hydraulic device according to claim 1, wherein the bypass passage is provided with a check valve that allows pressure oil to flow only from the second hydraulic pump toward the first hydraulic actuator.