JPH111171A - Emergency hydraulic steering system for hydraulic self-propelled vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an emergency hydraulic steering system for a hydraulic self-propelled vehicle dispensing with an emergency steering pump of conventional technique and unified by a hydraulic system. SOLUTION: An emergency hydraulic steering system for a hydraulic self-propelled vehicle having a traveling hydraulic motor 6 and a steering hydraulic actuator 11 has a first means (a pilot part of a second means 14) for detecting the steering pressure oil quantity being less than the specified quantity at the time of the steering hydraulic actuator 11 being operated and outputting detected information to the second means 14, the second means 14 for supplying travel pressure oil on the high pressure side between the inlet and outlet of the traveling hydraulic motor 6 to the steering hydraulic actuator 11 at the time of receiving the detected information of the first means (the pilot part of the second means 14), and has suction safety valves 15a, 15b at the inlet and outlet of the traveling hydraulic motor 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emergency hydraulic steering system for a hydraulic self-propelled vehicle.

[0002]

2. Description of the Related Art In a hydraulic steering type vehicle, if a hydraulic steering system is damaged or an engine or the like fails, steering cannot be performed. However, since the hydraulic steering system is a security device, an emergency hydraulic steering device is mounted on a so-called hydraulic steering vehicle so that the steering can be performed at any time and at any time. As an emergency hydraulic steering device, there is an example in which an emergency steering pump directly connected to an electric motor is driven by a current from a battery, and the hydraulic oil is transferred to a hydraulic steering system, thereby enabling emergency steering.

[0003]

However, the prior art has the following problems. (1) It is necessary to secure an emergency steering pump, a drive device for the emergency steering pump, and a space for mounting these components on the vehicle. (2) With a motor driven device, the emergency steering time is proportional to the capacity of the battery. However, in winter or the like, there is a problem that the battery capacity is unstable and sometimes emergency steering cannot be performed. In addition, when an emergency steering is performed for a long time (for example, 1 to 2 minutes) on an uneven road surface having a large steering resistance, there is a problem that the electric wire from the battery to the electric motor is heated and burned by a large current.

Some hydraulic self-propelled vehicles (in particular, construction machines) having a hydraulic working machine or the like have a hydraulic system as the traveling system in order to simplify the whole system with a hydraulic system.
In such a hydraulic self-propelled vehicle, it is required to provide an emergency hydraulic steering device. In this case, however, the problems (1) and (2) of the related art are solved, and the emergency hydraulic steering device is also entirely hydraulically operated. It is hoped that they will be unified.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an emergency hydraulic steering system for a hydraulic self-propelled vehicle, which does not require an emergency steering pump as in the prior art and is unified with a hydraulic system. And

[0006]

In order to achieve the above object, a first invention of an emergency hydraulic steering device for a hydraulic self-propelled vehicle according to the present invention comprises a traveling hydraulic motor, a steering hydraulic actuator, A first means for detecting that the steering pressure oil amount is smaller than a predetermined amount when the steering hydraulic actuator is actuated, and outputting detection information to the second means; When receiving the information, a second means for supplying the traveling hydraulic oil on the high-pressure side of either the entrance or the exit of the traveling hydraulic motor to the steering hydraulic actuator, and at the entrance and the exit of the traveling hydraulic motor It is characterized by having a suction safety valve.

According to the first aspect, the following operation and effect can be obtained. When the first means detects that the steering pressure oil amount is smaller than a predetermined amount when the steering hydraulic actuator is actuated, and outputs this detection information to the second means, the second means sets the inlet and outlet of the traveling hydraulic motor. The traveling pressure oil on the high pressure side is supplied to the steering hydraulic actuator. At this time, the shortage of the traveling pressure oil on the low pressure side is supplemented by the suction safety valve.

Therefore, even if the steering oil pressure is insufficient due to breakage of the steering hydraulic pump or steering pressure oil pipeline or engine failure, emergency steering of the hydraulic self-propelled vehicle becomes possible. Such an emergency steering pump becomes unnecessary. Therefore, a drive device such as an electric motor for driving the emergency steering pump is not required, and the configuration of the emergency hydraulic steering device is simplified, and an emergency hydraulic steering device for a self-propelled vehicle unified with a hydraulic system can be obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First to seventh embodiments of the present invention will be described with reference to FIGS.

Referring to FIG. 1, the structure of a first embodiment of the emergency hydraulic steering system according to the present invention will be described. The engine 1 is connected to a traveling hydraulic pump 2 and a steering hydraulic pump 3 so that they can be driven. The traveling hydraulic pump 2 and the tank 4
The self-propelled hydraulic circuit is connected to the traveling hydraulic motor 6 via the traveling operation valve 5 by a hydraulic pipeline to form an open circuit.
The output shaft of the traveling hydraulic motor 6 is drivably connected to the drive wheels 7. The discharge port of the steering hydraulic pump 3 is connected to the steering valve 10 via the check valve 8 and the steering pressure oil lines 9a and 9b, and the steering valve 10 and the steering hydraulic actuator 11 are connected by a hydraulic line. ing. The inlet / outlet of the traveling hydraulic motor 6 is connected to a relief valve 12a,
12b. The high pressure side of the entrance and exit of the traveling hydraulic motor 6 is connected to the steering pressure oil line 9 b via the shuttle valve 13 and the communication valve 14. In the first embodiment, the fact that the steering pressure oil amount is smaller than a predetermined amount is detected by the hydraulic pressure of the steering pressure oil line 9a. At the entrance of the traveling hydraulic motor 6, suction safety valves 15a and 15b capable of sucking oil from the tank 4 are provided. Although the traveling hydraulic pump 2 and the traveling hydraulic motor 6 are indicated by symbols of a variable discharge amount type, they may be of a fixed discharge amount type.

The operation of the configuration shown in FIG. 1 will be described.
(1) When the steering pressure oil is normally supplied to the steering pressure oil line 9a; the traveling pressure oil discharged from the traveling hydraulic pump 2 is supplied to the traveling hydraulic motor 4 according to the operation amount of the traveling operation valve 5.
And drives the hydraulic self-propelled vehicle by controlling the rotation direction and rotation speed of the drive wheel 5. The steering hydraulic pump 3
Is discharged by the check valve 8a and supplied to the steering pressure oil line 9b. The steering pressure oil is supplied to the steering hydraulic actuator 11 in accordance with the amount of operation of the steering valve 10 to steer the hydraulic self-propelled vehicle. The steering valve 10
The pipeline connecting the hydraulic actuator 11 and the steering hydraulic actuator 11 is restricted by the relief valves 16a and 16b so as not to exceed a predetermined pressure.

(2) When the pressure of the steering pressure oil drops due to a failure of the steering hydraulic pump 3 or the rupture of the steering pressure oil line 9a; the communication valve 14 is switched from the shut-off position a to the communication position b by the spring force. Be replaced. Therefore, the traveling pressure oil on the high pressure side of the traveling hydraulic motor 6 is supplied from the shuttle valve 13 to the steering pressure oil pipe 9b in accordance with the opening degree of the communication valve 14, then is shut off by the check valve 8 and is turned off by the check valve 8. Supplied to Therefore,
The hydraulic self-propelled vehicle is steered as in the normal state.

(3) When the hydraulic self-propelled vehicle becomes incapable of self-propelled due to a failure of the engine 1 or the traveling hydraulic pump 2, and the hydraulic self-propelled vehicle is towed and evacuated to a safe place;
Since there is no discharge pressure of the steering hydraulic pump 3, the communication valve 14 is at the communication position b. In this state, when the traveling operation valve 5 is operated to the neutral position c and the hydraulic self-propelled vehicle is towed, the discharge pressure oil of the traveling hydraulic motor 6 acting as a pump reduces the set pressure of the relief valve 12a or 12b. It is sucked into the traveling hydraulic motor 6 while being maintained. The traveling hydraulic motor 6
Is supplied to the steering pressure oil pipe 9b via the shuttle valve 13 and the communication valve 14, so that (1) and (2)
In this case, the hydraulic self-propelled vehicle can be steered. The shortage of the discharge pressure oil of the traveling hydraulic motor 6 supplied to the steering pressure oil line 9b is supplied from the tank 4 through the suction safety valve 15a or 15b.

A second embodiment of the emergency hydraulic steering system according to the present invention will be described with reference to FIG. The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. First,
The configuration of the second embodiment will be described. Steering pressure oil line 9b
An orifice 20 is interposed in the sensor to detect that the steering pressure oil amount is smaller than a predetermined amount due to a pressure difference between the upstream and downstream of the orifice 20. When the differential pressure of the orifice 20 is large, the communication valve 14 is switched to the shut-off position a, and when the differential pressure of the orifice 20 is small, the communication valve 14 is switched to the communication position b by the spring force. The other configuration is the same as that of the first embodiment, and the description is omitted.

The operation of the configuration shown in FIG. 2 will be described.
When the steering pressure oil is normally supplied to the steering pressure oil pipeline 9b, the steering pressure oil amount passing through the orifice 20 is large,
Since the differential pressure between the upstream and downstream of the orifice 20 is large, the communication valve 1
Reference numeral 4 denotes a blocking position a. Further, steering pressure oil discharged from the steering hydraulic pump 3 is shut off by the check valve 8 a and supplied to the steering valve 10. When the steering pressure oil amount in the steering pressure oil line 9b becomes lower than a predetermined amount due to a failure of the steering hydraulic pump 3 or the like, the differential pressure upstream and downstream of the orifice 20 decreases. To switch to the communication position b. Therefore, the traveling pressure oil of the traveling hydraulic motor 6 is supplied to the steering pressure oil pipeline 9 b via the shuttle valve 13. The other operation is the same as that of the first embodiment, and the description is omitted.

A third embodiment of the emergency hydraulic steering system according to the present invention will be described with reference to FIG. The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. First, the configuration of the third embodiment will be described. Since the steering is performed by the load sensing steering valve 10a, it is detected that the steering pressure oil amount is smaller than a predetermined amount due to a pressure difference between the load sensing steering valve 10a and the downstream. The oil discharged from the steering hydraulic pump 3 is supplied to the steering pressure oil line 9b and the working oil pressure line 25 by the oil amount switching valve 10b so that the pressure difference between the upstream and downstream of the load sensing steering valve 10a is constant. Since the load sensing steering control for switching is publicly known, the description is omitted. When the differential pressure of the load sensing steering valve 10a is large, the communication valve 14 is switched to the shut-off position a, and when the differential pressure of the load sensing steering valve 10a is small, the communication valve 14 is switched to the communication position b by spring force. The other configuration is the same as that of the first embodiment, and the description is omitted.

The operation of the configuration shown in FIG. 3 will be described.
When the steering pressure oil is normally supplied to the steering pressure oil pipe 9a and the operation oil amount of the load sensing steering valve 10a is smaller than the discharge oil amount of the steering pump 3, the upper and lower portions of the load sensing steering valve 10a. Of the communication valve 1
4 is switched to the blocking position a direction. Therefore, the traveling pressure oil of the traveling hydraulic motor 6 is not supplied to the steering pressure oil pipeline 9b. Further, when the operation oil amount of the load sensing steering valve 10a is larger than the discharge oil amount of the steering pump 3, the differential pressure between the upstream and downstream of the load sensing steering valve 10a decreases,
The communication valve 14 is switched in the direction of the communication position b by the spring force. Therefore, the traveling pressure oil of the traveling hydraulic motor 6 is supplied to the steering pressure oil line 9 b via the shuttle valve 13 in addition to the steering pressure oil discharged from the steering hydraulic pump 3. Therefore, the capacity of the steering hydraulic pump 3 can be reduced by the amount of the traveling pressure oil.
The amount of hydraulic oil discharged from the steering hydraulic pump 3 flowing through the hydraulic pump 5 can be reduced.

When the discharge pressure of the steering hydraulic pump 3 decreases due to a failure of the steering hydraulic pump 3 or the like,
The communication valve 14 is switched in the direction of the communication position b by the spring force, and the traveling pressure oil of the traveling hydraulic motor 6 is supplied to the shuttle valve 13.
Is supplied to the steering pressure oil pipeline 9b via the The other operations are the same as those of the first embodiment, and thus the description is omitted.

Referring to FIG. 4, a description will be given of a fourth embodiment of the emergency hydraulic steering system according to the present invention. The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
First, the configuration of the fourth embodiment will be described. Engine 1
Is connected so as to drive the traveling hydraulic pump 2. The traveling hydraulic pump 2 is a double swing type variable displacement hydraulic pump controlled by a displacement control device 2a, and is connected to a traveling hydraulic motor 6 via a hydraulic pipeline to form a self-propelled hydraulic closed circuit. doing. The hydraulic pressure of the discharge pressure oil of the charge pump 22 driven by the traveling hydraulic pump 2 is set by the charge pressure setting valve 23, and the suction safety valves 15c, 15d are set.
Is charged to a hydraulic pipeline connecting the variable displacement hydraulic pump and the traveling hydraulic motor 6 via the. The traveling hydraulic motor 6 is indicated by a variable discharge rate symbol, but may be a fixed discharge rate type.

The operation of the configuration shown in FIG. 4 will be described.
Traveling hydraulic pump 2 controlled by displacement control device 2a
The hydraulic self-propelled vehicle is driven by controlling the rotation direction and the number of rotations of the drive wheels 7 based on the discharge direction and the discharge oil amount of the traveling pressure oil discharged from the vehicle.

Regarding the case where the steering pressure oil is normally supplied to the steering pressure oil line 9a and the case where the hydraulic pressure of the steering pressure oil line 9a decreases due to the failure of the steering hydraulic pump 3, etc.
The operation is the same as in the first embodiment. The shortage of the traveling pressure oil supplied to the steering pressure oil line 9b is determined by the suction safety valves 15c and 15c.
It is supplied from the charge circuit 24 via d and 15e.
The other operations are the same as those of the first embodiment, and thus the description is omitted.

Referring to FIG. 5, a fifth embodiment of the emergency hydraulic steering system according to the present invention will be described. The same members as those in the fourth embodiment are denoted by the same reference numerals, and description thereof will be omitted.
First, the configuration of the fifth embodiment will be described. However, the configuration other than the configuration shown in FIG. 5 is the same as that of the fourth embodiment.

Under normal conditions, the switching valve 17 switches in the direction of the drain position a by the discharge pressure of the steering hydraulic pump 3, so that the communication valve 14 is drained by the pilot pressure and switched in the direction of the shut-off position a by the spring force. If the steering pressure oil amount is smaller than a predetermined amount, the steering oil pressure is reduced.
7 is switched to the communication position b by spring force, and the communication valve 14
Is configured to switch in the direction of the communication position b by the charge pressure. The communication valve 14 is set so as to switch in the direction of the shut-off position a before the charge pressure becomes equal to or lower than the set pressure.

The operation of the configuration shown in FIG. 5 will be described.
When the discharge pressure of the steering pressure oil pump 3 decreases due to a failure of the steering pressure oil pump 3 or the like, the switching valve 17 switches to the communication position b, and the communication valve 14 switches in the direction of the communication position b. In this state, when steering is performed by the traveling pressure oil supplied to the steering supply line 9b via the shuttle valve 13, the charge pressure decreases when the traveling pressure oil amount supplied to the steering supply line 9b increases. However, the communication valve 14 switches to the shut-off position a before the charge pressure becomes equal to or lower than the pressure set by the spring 14c. As a result, the amount of traveling pressure oil that can be used for steering decreases, and the steering speed is temporarily limited. However, the occurrence of cavitation in the traveling pressure oil pipeline can be prevented. In this manner, the communication valve 14 is switched to a position where the charge pressure and the spring 14c are balanced, so that the charge pressure is maintained at the set pressure, and a traveling pressure oil amount that can be used for steering is secured. The other operations are the same as those of the fourth embodiment, and the description is omitted.

Referring to FIG. 6, a description will be given of a sixth embodiment of the emergency hydraulic steering system according to the present invention. The same members as those in the second and fourth embodiments are denoted by the same reference numerals, and description thereof will be omitted. First, the configuration of the sixth embodiment will be described. The configuration not shown in FIG. 6 is the same as that of the fourth embodiment. Orifice 2
0 is connected to the pilot portion of the communication valve 14 at the drain position a when the charge pressure is lower than the spring force of the spring 18c, and at the communication position b when the charge pressure is higher than the spring force of the spring 18c. The switching valve 18 is provided for switching between the two.

The operation of the configuration shown in FIG. 6 will be described.
The charge pressure decreases when the amount of travel pressure oil supplied to the steering pressure oil line 9b increases, but when the charge pressure falls below the pressure set by the spring 18c, the communication valve 14 closes the shut-off position a.
Switch in the direction. As a result, the amount of traveling pressure oil that can be used for steering decreases, and the steering speed is temporarily limited. However, the occurrence of cavitation in the traveling pressure oil pipeline can be prevented. As described above, the communication valve 14 is connected to the charge pressure and the spring 18c.
By switching to a position where is balanced, the charge pressure is maintained at the set pressure, and a traveling pressure oil amount that can be used for steering is secured. The other operations are the same as those of the second and fourth embodiments, and thus the description is omitted.

Referring to FIG. 7, a description will be given of a seventh embodiment of the emergency hydraulic steering system according to the present invention. The same members as those in the third and fourth embodiments are denoted by the same reference numerals, and description thereof will be omitted. First, the configuration of the seventh embodiment will be described. The configuration not shown in FIG. 7 is the same as that of the fourth embodiment. When the charge pressure is lower than the spring force of the spring 18c, the pipe line connecting the downstream side of the load sensing steering valve 10a and the pilot portion of the communication valve 14 is located at the drain position a.
The switching valve 18 that switches to the communication position b when the spring force is higher than the spring force 8c is provided.

The operation of the configuration shown in FIG. 7 will be described.
When the traveling pressure oil amount supplied to the steering pressure oil pipeline 9b increases, the charge pressure decreases. However, when the charge pressure becomes equal to or less than the pressure set by the spring 18c, the communication valve 14 closes the shut-off position a.
Switch in the direction. As a result, the amount of traveling pressure oil that can be used for steering decreases, and the steering speed is temporarily limited. However, the occurrence of cavitation in the traveling pressure oil pipeline can be prevented. As described above, the communication valve 14 is connected to the charge pressure and the spring 18c.
By switching to a position where the spring force is balanced, the charge pressure is maintained at the set pressure, and the traveling pressure oil amount that can be used for steering is secured. The other operations are the same as those of the third and fourth embodiments, and the description will be omitted.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of an emergency hydraulic steering device according to the present invention.

FIG. 2 is a view showing a second embodiment of the emergency hydraulic steering device according to the present invention.

FIG. 3 is a diagram showing a third embodiment of the emergency hydraulic steering device according to the present invention.

FIG. 4 is a view showing a fourth embodiment of the emergency hydraulic steering system according to the present invention.

FIG. 5 is a view showing a fifth embodiment of the emergency hydraulic steering device according to the present invention.

FIG. 6 is a view showing a sixth embodiment of the emergency hydraulic steering system according to the present invention.

FIG. 7 is a view showing a seventh embodiment of the emergency hydraulic steering device according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 engine 2 traveling hydraulic pump 2a displacement control device 3 steering hydraulic pump 5 traveling operating valve 6 traveling hydraulic motor 7 drive wheel 8 check valve 9 steering pressure oil pipeline 10 steering valve 10a load sensing steering valve (first means) 10b Oil amount switching valve 11 Steering hydraulic actuator 12a, 12b, 16a, 16b Relief valve 13 Shuttle valve 14 Communication valve (second means) 15a to 15e Suction safety valve 17 Switching valve (first means) 18 Switching valve 20 Orifice (First) Means) 21 clutch 22 charge pump 23 charge pressure setting valve 24 charge circuit

Claims (1)

[Claims] In a hydraulic self-propelled vehicle having a traveling hydraulic motor and a steering hydraulic actuator, (1) detecting that a steering hydraulic oil amount is smaller than a predetermined amount when the steering hydraulic actuator is actuated; A first means for outputting detection information to the second means, and (2) when receiving the detection information of the first means,
A second means for supplying the traveling hydraulic oil on the high pressure side of either the inlet or the outlet of the traveling hydraulic motor to the steering hydraulic actuator, and (3) a suction safety valve at the entrance and the exit of the traveling hydraulic motor. An emergency hydraulic steering device for a hydraulic self-propelled vehicle.