JPH0610162Y2 - Hydraulic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a hydraulic control device in which a throttle control valve is used.

(Prior Art) As a hydraulic device using a throttle control valve, for example, a hydraulic rear wheel steering device as shown in FIG. 7 has been developed.

The steering wheel 3 will be described.
The piston 8 in the power cylinder 6 of the power steering device 4 is held in the neutral position during straight running of the vehicle in which is held in the neutral position, and the left chamber 9a and the right chamber 9b are in an equal pressure state. Therefore, in this case, the pilot signal pressure introducing chambers 36a and 36b of the throttle control type control valve 33 are provided.
Is held in an equal pressure state, and the spool 35 is also held in a neutral position, so that the hydraulic pressure does not act on the hydraulic actuator 24, and the rear wheels 2 and 2 are in a straight traveling state as shown by the solid line in FIG. Held in.

Further, when the vehicle in the high-speed running state is turned to the left, the piston 8 in the power cylinder 6 is moved to the right from the neutral position as the steering wheel 3 is steered. Therefore, the front wheels 1, 1 are steered to the left as shown by the dotted line in FIG. 7 in conjunction with the operation of the piston 8. Furthermore, when moving from the neutral position of the piston 8 in the power cylinder 6 to the right, the hydraulic pressure in the left chamber 9a is changed to the right chamber 9a.
It is higher than b. Therefore, the hydraulic pressure in the pilot signal pressure introducing chamber 36a on the left side of the control valve 33 becomes higher than the hydraulic pressure in the pilot signal pressure introducing chamber 36b on the right side, so that the spool 35 of the control valve 33 moves to the right and the spool 35 Between the first and third ports 40a and 40c of the spool 34 and the second and fifth ports 40b and 40e of the sleeve 34, respectively. , And the second valve chamber 39b of the spool 35 and the fourth and sixth ports 40d, 40f of the sleeve 34 are connected to each other for switching operation. In this way, the pilot signal pressure acting on the control valve 33 is substantially the pressure generated by the power steering device, and the control valve 33 controls the throttle amount according to the steering force to control the hydraulic pressure supplied to the hydraulic actuator 24. It has become a thing. Then, the hydraulic oil discharged from the oil pump 26 driven by the differential device 25 passes through the oil introducing passage 41 of the hydraulic circuit 32 to the control valve 3
3, the control valve 33 generates hydraulic pressure according to the amount of communication throttle with the return system passage 42 side, and is introduced into the right chamber 29b of the hydraulic cylinder 27 via the second oil passage 43b. The right chamber 29b of the cylinder 27 is in a high pressure state, and the left chamber 29a of the hydraulic cylinder 27 is in a low pressure state by being communicated with the reservoir tank 13 via the first oil passage 43a and the oil return passage 42. As a result, the piston 28 of the hydraulic cylinder 27 moves to the left, and the trailing arm 19, via the piston rod 30 and the operating rods 31, 31 is interlocked with the operation of the piston 28.
The rear end portions of the rear arms 21b and 21b of the 19 are pushed to the left and the rear wheels 2 and 2 are steered to the left. The rear wheels 2 are steered to the same phase as the front wheels 1 to run at high speed. It is intended to improve the running stability of the vehicle in the turning state.

Further, when the vehicle in the low speed traveling state is turned to the left, the piston 8 in the power cylinder 6 is moved to the right from the neutral position so that the hydraulic pressure in the left chamber 9a in the power cylinder 6 is greater than that in the right chamber 9b. The hydraulic pressure in the pilot signal pressure introducing chamber 36a on the left side of the control valve 33 becomes higher than the hydraulic pressure in the pilot signal pressure introducing chamber 36b on the right side, so that the spool 35 moves to the right, but at low speed traveling. Since the discharge flow rate of the oil pump 26 which is driven by the differential device 25 and rotates according to the vehicle speed is small and the hydraulic pressure generated by the control valve 33 is also small, the rear wheels 2 and 2 are not steered and are held straight. Note that the opposite operation to the above occurs when turning to the right.

(Problems to be solved by the invention) By the way, not only the above hydraulic rear wheel steering device,
In the hydraulic system using the throttle control valve, there is a problem that the viscosity of the hydraulic oil flowing in the hydraulic circuit changes depending on the temperature.

That is, when the oil temperature is low, the viscosity of the hydraulic oil is high, and when the oil temperature is high, the viscosity of the hydraulic oil is low. Therefore, in the above-mentioned configuration, even when the vehicle speed is the same and the steering force is the same (when the flow rate of hydraulic oil is the same and the throttle amount is the same), throttle control is performed when the oil temperature is low compared to when the oil temperature is high. There is a problem that the hydraulic pressure generated by
The steering angle of the rear wheels, which is determined by the hydraulic pressure applied to No. 4, changes depending on the oil temperature, which causes a problem that the steering characteristics of the rear wheels change depending on the temperature of the hydraulic oil.

That is, the conventional hydraulic pressure generator using a throttle valve has a drawback that the viscosity of the hydraulic oil changes depending on the temperature, so that the output pressure also changes depending on the temperature. That is, even with the same amount of throttle, the viscosity increases and the generated pressure also increases at low temperatures. On the contrary, it becomes low at high temperature.

As a method of eliminating this, it is conceivable to change the hydraulic oil to one having a characteristic of little change in viscosity, but the cost is usually high, and the effect is small and it cannot be completely eliminated.

There is also a method of changing the inflow flow rate depending on the temperature by adding a flow rate control device, but in a constant displacement type pump, 100% control is not possible with a simple method (the control structure becomes complicated and mechanical control is not possible). I can't handle it). In addition, if electronic control is used, the cost will be greatly increased, and the reliability will decrease.

[Constitution of device]

(Means for Solving Problems) The present invention was devised in view of the above, and controls the communication throttle amount of the high pressure oil passage to which the hydraulic oil is supplied from the hydraulic pressure source to the low pressure oil passage to A first throttle control valve configured to control the hydraulic pressure supplied to the hydraulic actuator side, and a volume expansion that is interposed between the high-pressure oil passage and the low-pressure oil passage and that is dependent on the temperature of the operating oil flowing therethrough. And a second throttle control valve configured to increase a communication throttle amount between the high pressure oil passage and the low pressure oil passage in accordance with a volume expansion of the wax. The gist is a characteristic hydraulic control device.

(Operation) According to the present invention, when the oil temperature rises with respect to the communication throttle amount controlled by the first throttle control valve, the generated hydraulic pressure decreases,
When the oil temperature decreases, the generated oil pressure tends to increase. However, on the second throttle control valve side, when the oil temperature rises, the wax expands, the amount of communication throttling to the low pressure oil passage increases, and the generated oil pressure increases. When the oil temperature decreases, the wax contracts and the amount of communication throttling to the low pressure oil passage decreases, so the generated hydraulic pressure tends to decrease. Therefore, the influence of the oil temperature (viscosity) generated on the first throttle control valve side Can be compensated by the second throttle control valve, and the problem that the generated oil pressure changes due to the oil temperature (viscosity change) is solved.

(Embodiment) Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS.

In this embodiment, the present invention is embodied in place of the control valve 33 of the rear wheel steering system shown in FIG. 7. The components corresponding to those in FIG. The description is omitted.

In FIG. 1, reference numeral 51 is a first throttle control valve, which has three chamfer parts 53 a, 53 b, 53 in a cylinder 52.
A spool 53 having c is slidably inserted. Left and right pilot signal pressure introducing chambers 54a and 54b are formed between both ends of the spool 53 and the cylinder 52, and these chambers 53a and 53b are connected to the oil passage 38a.
38b through the pressure chamber 9 of the power steering device 4
a and 9b, respectively. In addition, each room 54
Neutral springs 55a for biasing the spool 53 to the neutral position via sleeves 56a, 56b in a, 54b,
55b is interposed, these springs 55a,
55b is mounted in a preloaded state. Further, the cylinder 52 is provided with five ports 57a to 57e whose communication opening degree and communication throttle amount are controlled by the displacement position of the spool 53.
The a and 57c are communicated with the discharge port of the oil pump 26 via an oil passage 41 that forms a high-pressure oil passage. Further, the return port 57b communicates with the reservoir 13 via the return passage 42 which is a low pressure oil passage. Also, output port 5
7d and 57e are connected to the left and right pressure chambers 29a and 29b of the hydraulic actuator 24 through oil passages 43a and 43b.

Then, the first throttle control valve 51 having such a configuration
For example, when a signal pressure is introduced into the pilot signal pressure introduction chamber 54a on the left side, the spool 53 moves to the right and between the inflow port 57a and the output port 57d and between the output port 57e and the return port 57b. In the above, the communication throttle amount increases (the communication opening degree decreases), but the communication opening degree increases between the output port 57d and the return port 57b and between the inflow port 57c and the output port 57e. Therefore, the hydraulic oil supplied from the oil passage 41 flows in from the inflow port 57c, generates hydraulic pressure according to the amount of communication throttling with the return port 57b (the amount of overlap between the chamfer portion 53b and the cylinder inner wall), and outputs it. At the same time as being output from the port 57e, the hydraulic oil is returned from the output port 57d side to the return port 57b. Also,
When the signal pressure is introduced into the pilot signal pressure introducing chamber 54b on the right side, the operation reverse to the above is performed. On the other hand, reference numeral 61 in FIG. 1 is a second throttle control valve, and a spool 63 is slidably inserted in the cylinder 62. The spool 63 is slidably driven by a wax type control device 64 provided at one end of the throttle control valve 61. This wax type control device 64
Is provided in the return passage 42, a casing 65 fixed to the end of the cylinder 62 is formed with a temperature-sensitive greenhouse 66 in which hydraulic oil flows, and the temperature-sensitive drive unit 6 is provided in the temperature-sensitive chamber 66.
7 is provided and configured. The temperature-sensitive driving unit 67 has a rod 68 whose one end is fixed to the spool 63, and the rod 68 is slidably supported by a sleeve 69 fixed in the casing 65. An elastic member 71 formed in a hat shape is externally inserted and fixed to the other end of the rod 68, and an annular flange portion 70 formed on the opening side is fixed to the sleeve 69. The metal cup 72 is caulked and coupled to the sleeve 69 to form a fluid chamber with the elastic member 71. Wax 73 is enclosed in the fluid chamber and the temperature-sensitive drive unit 6 is provided.
7 are configured. Incidentally, 74 and 75 are seal rings, and 76 is a rubber ring.

In addition, a spool 63 in the cylinder 62 and a return spring 77 on the other end side are housed in a chamber 80,
Reference numeral 81 is for opening the atmosphere or guiding return oil.

Further, the cylinder 62 is formed with two inflow ports 78a and 78b which communicate with the oil passages 43a and 43b, respectively. The inflow port 78 depends on the position of the spool 63.
The amount of communication throttling between a and 78b is controlled.

Then, the second control valve 61 having such a configuration is
When the temperature of the hydraulic oil flowing into the greenhouse 66 from the return passage 42 rises, the wax 73 expands and the elastic member 7
While deforming 1, the rod 68 and the spool 63 move to the left in the drawing, and the amount of communication throttle between the ports 78a and 78b (the chamfer portion 63a of the spool 63 and the cylinder 6).
The amount of overlap with the inner wall of 2) increases, and the port 78
The pressure difference between a and 78b increases. On the contrary, when the temperature of the hydraulic oil decreases, the spool 63 moves to the right in the figure and the communication throttle amount decreases, so that the pressure difference between the ports 78a and 78b decreases.

As described above, according to the present embodiment in which the first throttle control valve 51 and the second throttle control valve 61 are provided, the following actions can be obtained.

First, when the inflow rate is constant (pump rotation speed is constant) and the throttle amount is constant (spool movement amount is constant, that is, pilot signal pressure is constant), the hydraulic pressure generated by the first throttle control valve 51 is
As shown in FIG. 2, the temperature rises at low temperatures and decreases at high temperatures.

Further, in the second throttle control valve 52, when the oil temperature changes with respect to a constant flow rate, the communication throttle amount increases as the oil temperature rises, so that the generated hydraulic pressure (pressure difference between ports) as shown in FIG.
Decreases at low temperatures and decreases at high temperatures.

Therefore, in the above embodiment, the change in the generated oil pressure due to the change in the oil temperature (viscosity) generated in the first throttle control valve 51 is caused by the output ports 57d, 5d of the first throttle control valve.
Compensated by the temperature dependence of the second throttle control valve that controls the communication throttle amount between 7e, and the oil passage 43a or 43b is compensated.
The hydraulic pressure supplied to the hydraulic actuator 24 via
It can be made almost constant with changes in oil temperature. Therefore, in the hydraulic rear wheel steering system as shown in FIG. 7, the steering angle of the rear wheel generated can be made substantially constant with respect to the oil temperature at a constant steering force and a constant vehicle speed, and the steering can be performed. Safety and safety are improved. 3 to 6 show a second embodiment of the present invention, which is an improvement of the structure of the chamfer portion 63a of the first embodiment, and the other structures are the same as those of the first embodiment. , Detailed description of other parts is omitted.

As shown in FIG. 3, the spool 6 of the second throttle control valve 61
The chamfered portion 63a of No. 3 is additionally formed with a cutout portion 80 whose cutout amount gradually changes in the length direction. Therefore, the second throttle control valve 61 is provided with the cutout portion 80.
In a region located in the vicinity of the ports 78a and 78b, the communication throttle amount (the overlap area between the chamfer portion 63a and the cylinder inner wall) changes non-linearly with respect to the displacement of the spool 63 (change of the oil temperature). Becomes

By the way, in the first embodiment, the non-linear temperature dependence generated in the first throttle control valve (the change in the viscosity with respect to the change in the oil temperature is a non-linear characteristic) is compared with the non-linear temperature dependence. Since it was compensated for by the second throttle control valve that it had, it was not possible to completely compensate for the change in the hydraulic pressure acting on the actuator due to the oil temperature. However,
According to the second embodiment, by providing the notch 80, the temperature dependence of the second throttle control valve 61 is opposite to that of the first throttle control valve as shown in FIG. Since the non-linear characteristic can be obtained, the effect that the hydraulic pressure supplied to the hydraulic actuator 21 can be made constant with respect to the change in the oil temperature is achieved.

In addition, in the present embodiment, the shape of the notch 80 is the fifth
The shape shown in FIG. 6 may be used.

[Effect of device]

As described above in detail with the embodiments, according to the present invention, the hydraulic pressure supplied to the hydraulic actuator can be stabilized against changes in the oil temperature.

[Brief description of drawings]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a configuration diagram, FIG. 2 is a characteristic diagram, and FIGS. 3 to 6 show a second embodiment of the present invention. Fig. 3 is a schematic diagram of the main parts, and Fig. 4
The figure is a characteristic diagram, FIGS. 5 and 6 are main part configuration diagrams showing a modified example of the second embodiment, and FIG. 7 is a schematic configuration diagram showing a conventional example. 51 ... First throttle control valve 61 ... Second throttle control valve 73 ... Wax

Claims (1)

[Scope of utility model registration request] 1. A hydraulic actuator is provided between a hydraulic power source and a hydraulic actuator by controlling a communication throttle amount of a high-pressure oil passage to which a hydraulic oil from the hydraulic power source is supplied to a low-pressure oil passage. A first throttle control valve configured to control hydraulic pressure, and a wax that is interposed between the high-pressure oil passage and the low-pressure oil passage and that has a volume expansion according to the temperature of the operating oil flowing therein is enclosed. And a second throttle control valve configured to increase the communication throttle amount between the high pressure oil passage and the low pressure oil passage in accordance with the volume expansion of the wax. apparatus.