JPH09277947A - Emergency steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a compact form and an energy saving by providing a priority valve having a first port for arranging first and second check valves in order toward an accumulator and connecting them to the accumulator, and a second port directly connected to the accumulator. SOLUTION: In the neutral position So of a steering valve 3, an inflow port 34 of pressure oil from a hydraulic pump 1 and a drain port 35 are provided, and a first check valve 36 for stopping the oil flow from the inflow port 34 to the drain port 35 is arranged in the oil passage between both the ports 34, 35. A priority valve 6 has a first port 64 for connecting the first check valve 36 and a second check valve 8 for stopping the oil flow from an accumulator 5 to an unload relief valve 7 in order toward the accumulator 5 and connecting them to the accumulator 5, and a second port 65 directly connected to the accumulator 5. Thus, the device can be made compact, and energy saving can be attained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an emergency steering system.

[0002]

2. Description of the Related Art A self-propelled vehicle is equipped with a steering device having a steering valve in an oil passage from a hydraulic pump to a steering actuator, the steering valve being capable of supplying the steering actuator with a flow rate following the movement of a steering operation rod. There is something. Then, there is the following emergency steering device in which the hydraulic pump fails and, for example, when the lane is given to the following vehicle, steering is possible only during that time.

(1) An emergency hydraulic pump driven by an electric motor is added, and the current from the battery is guided to the electric motor to drive the emergency hydraulic pump, and the discharged oil is sent to a steering valve for emergency steering. What was made possible.

(2) An accumulator is added in the oil passage between the steering valve and the hydraulic pump to accumulate pressure, and this pressure oil is sent to the steering valve to enable emergency steering.

[0005]

However, the above-mentioned prior art has the following problems. (1) In a system in which an emergency hydraulic pump driven by an electric motor is added, it is necessary to secure a space for installing the electric motor and the emergency hydraulic pump, and securing a space for the installation is a problem in a small vehicle. In addition, it is difficult to perform emergency steering in the winter when the battery performance deteriorates.

(2) In the system in which the accumulator is simply added in the oil passage between the steering valve and the hydraulic pump, the accumulated pressure of the accumulator is added to the hydraulic pump as back pressure, so that the driving torque of the hydraulic pump increases. Energy loss.

The present invention has been made in view of the above-mentioned problems of the prior art,
It is an object to provide a compact and energy-saving emergency steering device.

[0008]

In order to achieve the above object, the first emergency steering device is, for example, as shown in FIG.
In the steering device having a steering valve capable of supplying to the steering actuator a flow rate that follows the operation of the steering operation rod in the oil passage from the hydraulic pump to the steering actuator, the neutral position So The steering valve 3 has a pressure oil inflow port 34 and a drain port 35, and a first check valve 36 for stopping an oil flow from the inflow port 34 to the drain port 35 in an oil passage between the ports 34, 35. An accumulator 5 provided upstream of the steering valve 3, an inlet port 63 for pressure oil from the hydraulic pump 1 on the upstream side, and an inlet port 72 for pressure oil on the upstream side on the downstream side. The downstream side has a drain port 73 that opens when the internal pressure of the accumulator 5 reaches a predetermined pressure. Unload relief valve 7
And the unload relief valve 7 from the accumulator 5
With a second check valve 8 for stopping the oil flow to the accumulator 5 and a first port 64 connected to the accumulator 5 and a second port 65 directly connected to the accumulator 5. It is characterized by having a valve 6.

According to the first emergency steering system, even if the steering valve 3 is in the neutral position So, the neutral position So is
In addition, since the first check valve 34 is provided, the second check valve 8 that stops the amount of oil upstream and the priority valve 6 that closes when the accumulator 5 has completed accumulating pressure are provided upstream of the accumulator 5. Since it is provided, the accumulated pressure in the accumulator 5 can be maintained. Further, in the flow path between the hydraulic pump 1 and the accumulator 5, the priority valve 6 and the second check valve 8 are provided.
And an unload relief valve 7 which is a relief valve when receiving pressure from the accumulator 5 when accumulating pressure, and an unload valve when pressure accumulation is completed, so that the accumulator 5 accumulates a predetermined amount of pressure ( That is, after the pressure accumulation is completed), the load on the hydraulic pump 1 disappears. That is, not only energy saving by the conventional accumulator 5 but also driving energy for the hydraulic pump 1 after the accumulator 5 has completed accumulating pressure can be saved.

On the other hand, the second emergency steering device, for example, referring to FIG. 2, supplies to the steering actuator a flow rate that follows the operation of the steering operation rod in the oil passage from the hydraulic pump to the steering actuator. In a steering device having a enabled steering valve, a variable displacement hydraulic pump 10, a pressure oil inflow port 34 and a drain port 35 at a neutral position So, and an oil passage between both ports 34, 35. A steering valve 3 having a first check valve 36 for stopping the oil flow from the inflow port 34 to the drain port 35, an accumulator 5 provided upstream of the steering valve 3, and an upstream provided upstream of the accumulator 5. Check valve 9 for stopping the oil flow to the third check valve Unloading, which is provided on the upstream side of the variable displacement hydraulic pump 10 and has a drain port 73 on the downstream side that opens when the internal pressure of the accumulator 5 reaches a predetermined pressure A relief valve 7 and a servo mechanism 11 that receives the internal pressure of the accumulator 5 and reduces the discharge oil amount of the variable displacement hydraulic pump 10 when the internal pressure is high.

According to the second emergency steering device, the hydraulic pump is the variable displacement hydraulic pump 10, and the inflow to the upstream is stopped in the flow path between the variable displacement hydraulic pump 10 and the accumulator 5. 3 check valves 9
When the internal pressure of the accumulator 5 is accumulated, the pressure is a relief valve, while when the pressure accumulation is completed, the unload relief valve 7 serves as an unload valve, and when the internal pressure of the accumulator 5 is high, the variable displacement hydraulic pressure Pump 1
Since it has the servo mechanism 11 for reducing the discharged oil amount of 0, pressure accumulation and replenishment can be performed rapidly, and drive energy of the variable displacement hydraulic pump 10 can be saved when pressure accumulation is completed. Even when the steering valve 3 is in the neutral position So, the neutral position So is the same as in the first emergency steering device.
Since the first check valve 34 is included in the accumulator 5, the pressure accumulation in the accumulator 5 can be maintained, and energy saving by the accumulator 5 can be obtained.

That is, in both the first and second emergency steering devices, unlike the prior art, an emergency hydraulic pump with an electric motor is not required to secure an additional space, is not affected by the weather, and saves energy. Has achieved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A first example will be described with reference to the schematic hydraulic circuit diagram of FIG. As shown in FIG. 1, a steering valve 3 is provided in an oil passage from the hydraulic pump 1 to the steering actuator 2. The hydraulic pump 1 is a fixed displacement type or a variable displacement type, and is driven by, for example, the engine M to supply pressure oil to the steering valve 3. In this example, the steering actuators 2 are two hydraulic cylinders provided separately on the left and right sides of the vehicle body of the self-propelled vehicle, and each head side and bottom side are cross-piped to the steering valve 3 for smooth steering operation. Connected. In order to protect the cross pipe and the hydraulic cylinder 2 from accidentally generated high pressure, the cross pipes are connected to each other by a crossover relief valve 4. The steering valve 3 is rotatably provided at a base end of a steering operation rod 31 (so-called steering wheel) together with a metering pump 32.
It is a position switching valve. 3 position is steering wheel 31
Has a left position SL and a right position SR based on the operating force of, and a neutral position So based on the biasing force of the neutral springs 33L and 33R. The neutral position So has an inflow port 34 and a drain port 35 for the pressure oil from the hydraulic pump 1, and the space between both ports is 3
In the oil passages 4 and 35, the inflow port 34 to the drain port 3
It has a first check valve 36 which shuts off the oil flow to 5.
An accumulator 5 is provided in the oil passage from the hydraulic pump 1 to the steering valve 3. Further, in the oil passage from the hydraulic pump 1 to the accumulator 5, there is an unloading port that has a pressure oil inflow port 72 on the upstream side and a drain port 73 that opens when the internal pressure of the accumulator 5 reaches a predetermined pressure on the downstream side. A relief valve 7 and a second check valve 8 for stopping the oil flow from the accumulator 5 to the unload relief valve 7 are sequentially arranged toward the accumulator 5 and connected to the accumulator 5;
It has a priority valve 6 having a second port 65 directly connected to the accumulator 5 and a downstream side.

That is, the priority valve 6 is at the position S.
1 and S2. Each of the positions S1 and S2 is a 3-port 2-position switching valve having one port 63 on the upstream side and one port 64 and the second port 65 on the downstream side. The port 63 is connected to the hydraulic pump 1. First port 64
Is connected to the accumulator 5 via the unload relief valve 7 and the second check valve 8. Second port 65
Is directly connected to the accumulator 5. At the position S1, the second port 65 is closed and the port 63 and the first port 64 are communicated with each other through the orifice 62a. At the position S2, the port 63 is branched and one side is the orifice 62b.
Through the first port 64, and the other communicates with the second port 65. This priority valve 6 is a spring 6
1 and normally maintains the position S1 by its urging force. The hydraulic pressure on the side of the first port 64 is guided to the spring 61 side as the pilot pressure P1, while the discharge pressure of the hydraulic pump 1 is guided to the counter spring side as the pilot pressure P2.

The basic steering operation in the first case is as follows. If the steering wheel 31 is cut to the left, this operating force pushes and contracts the neutral spring 33L to switch the steering valve 3 from the neutral position So to the left position SL. At the same time, the metering pump 32 is rotated by the amount corresponding to the turning of the steering wheel 31. Therefore, the metering pump 32 meters the flow rate from the steering valve 3 to the hydraulic cylinder 2. On the other hand, when the steering wheel 31 is stopped, since the operating force is lost, the neutral springs 33L and 33R balance each other and return the steering valve 3 to the neutral position So. That is, the steering valve 3 supplies the hydraulic cylinder 2 with a flow rate that follows the operation of the steering wheel 31.

On the other hand, the emergency steering operation in the first case is as follows. For example, it is assumed that the hydraulic pump 1 and the engine M cannot rotate. If the engine becomes unrotatable, it will be towed by another vehicle. At this time, if the steering wheel 31 is turned off, the pressure-accumulated oil in the accumulator 5 flows into the steering valve 3 to enable emergency steering. By the way, accumulator 5
Accumulation of pressure and release of pressure are performed as follows.

The priority valve 6 is, as described above,
Normally, the position P1 is maintained by the biasing force of the spring 61. However, immediately after the accumulator 5 is replaced, for example, the accumulator 5 is empty. At this time, since the internal pressure of the accumulator 5 is low, the following first action and second action occur. The first effect is that the unload relief valve 7 becomes a relief valve by the urging force of its spring 71, and enables the circuit pressure from the hydraulic pump 1 to the accumulator 5 (that is, pressure accumulation). The second effect is that when the hydraulic pump 1 is driven, the pressure oil from the hydraulic pump 1 flows into the accumulator 5, but the flow rate is extremely large,
The differential pressure across the orifice 62a becomes large (P1 <<
P2), the force based on this differential pressure overcomes the urging force of the spring 61 to move the priority valve 6 from the position S1 to the position S2.
To switch to.

When the position S1 is switched to the position S2 by the second action, the amount of oil from the hydraulic pump 1 flows into the accumulator 5 from the first port and the second port having a small internal resistance. When the accumulator 5 approaches full (that is, when the internal pressure of the accumulator 5 rises due to the first action), the flow rate flowing through the position S2 also gradually decreases, and the internal pressure of the accumulator 5 also increases, so that the orifice 62b at the position S2 The differential pressure between the front and back becomes smaller (P1-P2 =
(Small), the force based on this pressure difference is defeated by the biasing force of the spring 61 to return the priority valve 6 from the position S2 to the position S1. After that, when the force based on the internal pressure of the accumulator 5 overcomes the urging force of the spring 71 of the unload relief valve 7, the unload relief valve 7 is fully opened and becomes the unload valve.

Since the second check valve 8 and the position S1 of the priority valve 6 contain the internal pressure of the accumulator 5, the internal pressure of the accumulator 5 does not decrease, and the unload relief valve 7 is the unload valve. Therefore, the load on the hydraulic pump 1 is eliminated.

If the steering wheel 31 is not operated, the steering valve 3 will be in the neutral position So.
The first check valve 34 at the neutral position So maintains the internal pressure of the accumulator 5 without draining.

On the other hand, when the steering wheel 31 is operated to switch the steering valve 3 from the position So to the position SL (or SR), the internal pressure of the accumulator 5 decreases. When the force based on this internal pressure is reduced to the urging force of the spring 71 of the unload relief valve 7, replenishment of the amount of oil to the accumulator 5 starts. There are two ways to replenish.

First, when the steering wheel 31 is normally operated, the accumulator 5 receives a small amount of replenishment from the hydraulic pump 1 via the normal position S1 of the priority valve 6. Secondly, for example, the steering wheel 31
When the end cut operation of (the operation of switching from the stroke end of the hydraulic shilling 2 to one stroke end) is rapidly repeated, the amount of accumulated pressure in the accumulator 5 decreases sharply,
Along with this, the amount of replenished oil to the accumulator 5 and the hydraulic cylinder 2 increases rapidly. At this time, the priority valve 6 is moved to the position S due to the pressure difference effect of the orifice 62a.
Switching from 1 to the position S2, the large flow rate is replenished.

Regarding the replenishment to the accumulator 5 shown in the first and second above, the capacity of the accumulator 5 and the orifice 62 are used to determine the timing and the replenishment flow rate for switching the positions S1 and S2 of the priority valve 6.
It is appropriately set by a biasing force of a, 62b and the spring 61.

According to the first case, the steering valve 3
Even at the neutral position So, since the first check valve 34 is provided at the neutral position So, and also upstream of the accumulator 5,
Since the second check valve 8 for stopping the amount of oil to the upstream side and the priority valve 6 which is closed when the accumulator 5 has completed the pressure accumulation, the pressure accumulation in the accumulator 5 can be maintained. Further, in the flow path between the hydraulic pump 1 and the accumulator 5, the priority valve 6, the second check valve 8 and the accumulator 5 are internal pressures of the accumulator 5 and are a relief valve at the time of accumulating pressure, while a pressure accumulation is completed. Is equipped with an unload relief valve 7 serving as an unload valve, the hydraulic pump 1 is operated after the accumulator 5 has accumulated a predetermined amount of pressure (after the completion of pressure accumulation).
The load of is lost. That is, not only energy saving by the conventional accumulator 5 but also driving energy for the hydraulic pump 1 after the accumulator 5 has completed accumulating pressure can be saved.

The second case will be described with reference to the schematic hydraulic circuit diagram of FIG. The same elements as those in the first case in the description of the second case are designated by the same reference numerals, and the duplicated description will be omitted.

In the second case, as in the first case, the hydraulic cylinder 2 has a flow rate that follows the operation of the steering wheel 31 which is a steering operation rod, in the oil passage from the hydraulic pump to the two hydraulic cylinders 2 which are steering actuators. The steering valve 3 for supplying the Then, the steering valve 3 has the pressure oil inflow port 34 and the drain port 35 at the neutral position So as in the first example, and from the inflow port 34 to the drain port 35 in the oil passage between both ports 34, 35. Has a first check valve 36 for stopping the oil flow. The big difference between the second case and the first case is that the frame A of the first case shown in FIG. 1 in FIG. 1 becomes like the frame B of the second case shown in FIG. is there. Details are as follows.

However, the hydraulic pump 1 is a variable displacement hydraulic pump 10. An accumulator 5 is provided upstream of the steering valve 3. A third check valve 9 that stops the oil flow to the upstream is provided upstream of the accumulator 5. An unload relief valve 7 is provided upstream of the third check valve 9. The unload relief valve 7 has an inflow port 72 for pressure oil from the variable displacement hydraulic pump 10 on the upstream side, and an accumulator 5 on the downstream side.
Has a drain port 73 that opens when the internal pressure of the device reaches a predetermined pressure. It has a servo mechanism 11 that receives the internal pressure of the accumulator 5 and reduces the amount of oil discharged from the variable displacement hydraulic pump 10 when the internal pressure rises. The servo mechanism 11 may gradually decrease the amount of oil discharged from the variable displacement hydraulic pump 10 when the internal pressure gradually increases.

The steering operation and the emergency steering operation in the second case are the same as those already described in the first case.
By the way, in the second case, pressure accumulation and pressure release to the accumulator 5 are performed as follows.

For example, immediately after replacing the accumulator 5, the accumulator 5 is empty. At this time, first, the unload relief valve 7 becomes a relief valve because the internal pressure of the accumulator 5 is low. On the other hand, the servo mechanism 11 receives the internal pressure of the accumulator 5 and tilts the swash plate angle or the swash axis angle of the variable displacement hydraulic pump 10 to, for example, the maximum discharge amount side. At this time, as described above, since the unload relief valve 7 is a relief valve, it contributes to the accumulation of pressure in the accumulator 5. When the accumulated pressure is increased to a predetermined high pressure, the servo mechanism 11 reduces the discharge amount of the variable displacement hydraulic pump 10. As described above, the servo mechanism 11 may gradually decrease the amount of oil discharged from the variable displacement hydraulic pump 10 when the internal pressure gradually increases.

On the other hand, the unload relief valve 7 also receives the internal pressure of the accumulator 5, and when the force based on the internal pressure of the accumulator 5 overcomes the urging force of the spring 71 of the unload relief valve 7, the unload relief valve 7 becomes It comes to play the role of an unload valve, and drains all the discharge oil of the variable displacement hydraulic pump 10. At this time, the pressure accumulated in the accumulator 5 is maintained by the third check valve 9, so that the pressure accumulated oil in the accumulator 5 is not drained from the unload relief valve 7. Note that the first check valve 34 maintains the accumulated pressure of the accumulator 5 when the steering valve 3 is at the neutral position So, as in the first case.

That is, according to the second example, in the flow path between the hydraulic pump 1 and the accumulator 5, the third check valve 9 for stopping the inflow to the upstream side, and the internal pressure of the accumulator 5 are received to relieve when accumulating pressure. On the other hand, an unload relief valve 7 which is an unload valve when the pressure accumulation is completed, and a servo mechanism 11 which receives the internal pressure of the accumulator 5 and reduces the discharge oil amount of the variable displacement hydraulic pump 10 when the internal pressure is high. Since it has a pressure, the pressure can be rapidly accumulated and replenished, and when the pressure accumulation is completed, the variable displacement hydraulic pump 10
Driving energy can be saved. Even when the steering valve 3 is at the neutral position So, the first check valve 34 is provided at the neutral position So as in the first case.
Accumulator 5 can maintain the accumulated pressure, and accumulator 5
Energy savings can be obtained.

That is, in both the first and second cases,
As in the prior art, an emergency hydraulic pump driven by an electric motor is not required to secure an additional space, is not affected by the weather, and achieves energy saving.

[Brief description of drawings]

FIG. 1 is a schematic hydraulic circuit diagram of a first example.

FIG. 2 is a schematic hydraulic circuit diagram of a second example.

[Explanation of symbols]

 1 hydraulic pump 2 steering actuator 3 steering valve 31 steering operation rod 34, 63, 72 inflow port 35 drain port 36 first check valve 5 accumulator 6 priority valve 64 first port 65 second port 7 unload relief valve 73 drain port 8 Second check valve 9 Third check valve 10 Variable displacement hydraulic pump 11 Servo mechanism So Neutral position

Claims (2)

[Claims] 1. A steering device having a steering valve capable of supplying to the steering actuator a flow rate following the movement of a steering operation rod in an oil passage from a hydraulic pump to a steering actuator, wherein: A steering valve 3 having an inflow port 34 and a drain port 35, and a first check valve 36 for stopping the oil flow from the inflow port 34 to the drain port 35 in the oil passage between the ports 34, 35; An accumulator 5 provided upstream of the steering valve 3, and an inlet port 63 for pressure oil from the hydraulic pump 1 on the upstream side, and an inlet port 72 for pressure oil on the downstream side on the upstream side of the accumulator 5. An inlet having a drain port 73 on the downstream side that opens when the internal pressure reaches a predetermined pressure. Relief valve 7
And the unload relief valve 7 from the accumulator 5
With a second check valve 8 for stopping the oil flow to the accumulator 5 and a first port 64 connected to the accumulator 5 and a second port 65 directly connected to the accumulator 5. An emergency steering device having a valve 6. 2. A steering device having a steering valve capable of supplying to the steering actuator a flow rate that follows the operation of a steering operation rod in an oil passage from the hydraulic pump to the steering actuator. A first check valve having a pressure oil inflow port 34 and a drain port 35 at the neutral position So, and stopping an oil flow from the inflow port 34 to the drain port 35 in an oil passage between the ports 34, 35. A steering valve 3 having 36, an accumulator 5 provided upstream of the steering valve 3, a third check valve 9 provided upstream of the accumulator 5 for stopping an oil flow to the upstream, a third check valve 9 Inlet port 72 for the pressure oil from the variable displacement hydraulic pump 10 provided upstream of the An unload relief valve 7 having a drain port 73 on the downstream side that opens on the upstream side and opens when the internal pressure of the accumulator 5 reaches a predetermined pressure; and a variable displacement type when the internal pressure of the accumulator 5 is high and the internal pressure is high. An emergency steering device comprising: a servo mechanism 11 for reducing the amount of oil discharged from the hydraulic pump 10.