JPH05141402A - Hydraulic control device - Google Patents

Abstract

(57) [Summary] [Purpose] In a hydraulic system in which multiple actuators are driven by a single hydraulic pump that has a limit discharge oil amount that is less than the total maximum required oil amount, the discharge pressure is a predetermined value without using a pressure sensor. When it becomes the following, the flow rate of the flow control valve is limited and the flow rate to the auxiliary actuator via this is limited,
Prevents a decrease in the amount supplied to the main actuator. In a configuration in which hydraulic oil from a variable displacement pump 1 is supplied to a hydraulic motor 2 via hydraulic suspension actuators 5a to 5d and a flow control valve 8, a piston provided with a restriction valve 19 when the discharge pressure decreases 47 pushes the spool in the closing direction to limit the supply of hydraulic oil to the hydraulic motor 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control system for operating a plurality of actuators with a single hydraulic pump, and more particularly to a hydraulic control system for a vehicle mounted and used in a vehicle.

[0002]

2. Description of the Related Art It is disadvantageous to dispose a separate hydraulic pump in each of a plurality of hydraulic control devices mounted on a vehicle because of problems such as mounting space of the vehicle. A hydraulic system for a vehicle in which a plurality of actuators, for example, a hydraulic motor for a cooling fan and an actuator for a hydraulic suspension are operated by is considered. That is, the hydraulic oil is supplied from the variable displacement pump having the flow rate control function by the discharge pressure feedback to the cooling fan hydraulic motor via the flow rate control valve, and the hydraulic suspension actuator is also supplied via the pressure control valve. Is also supplied with hydraulic oil.

At this time, the engine operating conditions are severe,
In addition, a large-capacity hydraulic pump may be used in order to prevent the flow rate from becoming insufficient even under operating conditions in which the slalom operation or the like is performed and both the cooling fan hydraulic motor and the hydraulic suspension actuator require the maximum flow rates. However, arranging such a large-capacity hydraulic pump is disadvantageous in terms of vehicle mounting space, and not only space saving effect cannot be expected but also fuel consumption during normal driving deteriorates, so energy saving effect can also be expected. Not practical. Therefore, in order to save space and save energy, it is sufficient to use a small capacity variable displacement pump that has a limit discharge oil amount that is less than the total maximum required oil amount for each actuator. Needless to say, there will be a shortage of oil. That is, in such a hydraulic system, the relationship between the discharge pressure P and the discharge flow rate Q of the variable displacement pump is a straight line L as shown in FIG.
If the total required oil amount for each actuator is less than or equal to the limit discharge oil amount QMAX of the variable displacement pump, for example, if the flow rate is Q1, then the corresponding hydraulic pressure value P1 will be reached, but the total required oil amount for each actuator will exceed the flow rate QMAX. Then, as indicated by the broken line in FIG. 3, the discharge pressure P of the pump suddenly drops. As a result, the hydraulic pressure supplied to each actuator will decrease at the same time, and the performance of each actuator will decrease at the same time.

Therefore, the present applicant has previously filed Japanese Patent Application No. 2-1560.
As No. 17, a pressure sensor 110 for detecting the discharge pressure of the variable displacement pump is provided as shown in FIG. 4, and when the discharge pressure becomes a predetermined value or less, the flow control valve 108 is throttled to supply the cooling fan hydraulic motor 102. The hydraulic suspension actuators 105a, 105b, 1
It was possible to avoid the situation in which the performance of each actuator is reduced at the same time by proposing one that secures the amount of hydraulic oil supplied to 05c and 105d. That is, in order to secure the hydraulic oil to the hydraulic suspension actuators 105a, 105b, 105c, 105d, which has a great influence on the riding comfort of the vehicle, the supply of the hydraulic oil to the cooling fan hydraulic motor 102 is restricted. Are hydraulic suspension actuators 105a, 105b, 105
The state in which c and 105d require the maximum flow rate is momentary, and the working oil is immediately supplied to the cooling fan hydraulic motor 102, so that the engine cooling water does not rise excessively.

In addition, the applicant of the present invention has a separate Japanese Patent Application No. 2-18290.
In No. 5, a throttle valve is provided in the hydraulic pipe upstream of the control valve that controls the operation of the sub-actuator, and when the discharge pressure drops, the supply of hydraulic oil to the sub-actuator is automatically stopped and It was proposed to secure the hydraulic oil supply.

[0006]

However, the technique described in Japanese Patent Application No. 2-156017 mentioned above requires a pressure sensor for detecting the discharge pressure of the variable displacement pump, and therefore is costly. There was a problem.

Further, even in the above-mentioned Japanese Patent Application No. 2-182905, a throttle valve must be newly provided in the hydraulic pipe, and there is a problem that space efficiency and mounting workability are not good and cost is increased. there were.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a pump with a discharge pressure of a predetermined value or less without providing a pressure sensor for detecting the discharge pressure of the pump or providing a throttle valve in the hydraulic pipe. , To limit the flow rate of hydraulic oil supplied to the sub-actuator.

[0009]

In order to achieve the above object, the present invention provides one hydraulic pump for supplying hydraulic oil, and a main actuator and an auxiliary actuator driven by the hydraulic oil distributed from this hydraulic pump. A flow rate control valve provided between the hydraulic pump and the sub-actuator, the flow rate control valve having a spool for changing the flow rate of hydraulic oil supplied to the sub-actuator. And a limiting valve for operating the spool in a direction to reduce the supply flow rate to the sub-actuator when the discharge pressure falls below a predetermined value.

[0010]

In the hydraulic control device having the above structure, the hydraulic oil supplied from one hydraulic pump is distributed to the sub-actuator through a flow control valve having a spool for changing the flow rate of the hydraulic oil, and the remaining Dispense the hydraulic fluid in the main actuator. When the discharge amount of the hydraulic pump becomes close to the limit discharge amount and the discharge pressure becomes equal to or lower than a predetermined value, the spool is operated by the pressing member provided in the limiting valve in the direction of reducing the supply flow rate to the auxiliary actuator. A decrease in the amount of hydraulic oil supplied to the main actuator to be operated is suppressed, and a sufficient amount of hydraulic oil is supplied.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a vehicle hydraulic control device that is an embodiment of the present invention.

As shown in FIG. 1, a variable displacement pump (hydraulic pump) 1 supplies hydraulic oil to a cooling fan hydraulic motor (auxiliary actuator) 2 via a flow control valve 8 and a pressure control valve 3 Through the hydraulic suspension actuators (main actuators) 5a, 5b,
Hydraulic oil is also supplied to 5c and 5d. The discharge pressure P and the discharge flow rate Q of the variable displacement pump 1 are within the section A shown in FIG. 3 when the actuators 2, 5a, 5b, 5c and 5d do not require a large amount of hydraulic oil at the same time. Balance.

The flow rate control valve 8 controls the flow rate of the hydraulic oil supplied to the cooling fan hydraulic motor 2.
1 and a pressure compensator 13 that compensates for the difference between the supply pressure and the output pressure of the flow rate controller 11 to be constant so that the control flow rate does not change due to the load of the cooling fan hydraulic motor 2. Have.

The flow rate control section 11 includes a spool 15 for changing the flow rate in the body 21, and the spool 1.
5 has a proportional solenoid 17 for operating 5 and a limiting valve 19 for moving the spool 15 so as to limit the flow rate when the discharge pressure of the variable displacement pump 1 becomes a predetermined value or less. The proportional solenoid 17 is controlled by a controller 7 that outputs a command value based on a signal from an engine water temperature sensor 6 that detects the water temperature of engine cooling water.

On the other hand, the pressure compensating section 13 moves in the body 61 in accordance with the pressure difference between the supply pressure and the discharge pressure of the flow rate control section 11 so that the pressure difference becomes constant. Have. The body 61 is the body 2
1 is integrally connected with a bolt and a nut (not shown).

FIG. 2 is an enlarged sectional view of the flow control valve 8 shown in FIG.

The flow rate control unit 11 has a cylindrical insertion hole 25 along the longitudinal direction in the body 21, and the spool 15 can slide in the insertion hole 25 in the axial direction. .. A supply port 27 and an output port 29 communicating with the insertion hole are formed in the body 21 at predetermined positions.

The spool 15 has lands 15a and 15b formed at both ends thereof and an annular groove 15 formed at the center thereof.
c and the rightmost side in the figure, the land 15a
As a result, the communication between the supply port 27 and the output port 29 is cut off, and when moving to the left side in the figure, the communication opening degree increases.

Further, oil chambers 31 and 33 are respectively formed facing both ends in the axial direction of the spool 15, and the spool 15 is provided in the oil chamber 31.
A spring 23 having a predetermined spring constant is inserted to press in the direction of decreasing the communication opening degree between the supply port 27 and the output port 29.

The proportional solenoid 17 is connected to the oil chamber 33.
A plunger 37, which is provided on the side, is movable in an insertion hole 35 formed in the body 21, and an exciting coil 39. An actuator 41 is fixed to the plunger 37, and the actuator 41 is extended into the oil chamber 33 by loosely inserting the hole 42 in the wall surface of the body 21, and the spool 1 is provided at the tip thereof.
5 can be activated. The exciting coil 39 is supplied with a command signal i consisting of a current value from the controller 7 shown in FIG. 1, the plunger 37 generates a thrust force proportional to the command signal, and causes the spool 15 to move in a direction opposite to the spring 23.
That is, the supply port 27 and the output port 29 are pressed in the direction of increasing the communication opening degree.

The restriction valve 19 is provided on the oil chamber 31 side and has an insertion hole 45 formed in the body 21.
And a piston (pressing member) 47 movable in the insertion hole 45, and a spring 49 having a predetermined spring constant for pressing the piston 47 toward the oil chamber 31 side. Oil chambers 51 and 53 are formed between both axial end surfaces of the piston 47 and both wall surfaces of the insertion hole 45, and the oil chamber 53 on the oil chamber 31 side is formed.
Is communicated with a supply port 55, which will be described later, by an oil passage 98, and the discharge pressure of the variable displacement pump 1 is directly transferred to the piston 47.
The spring 49 is pressed in the direction opposite to the spring 49, that is, in the left direction in the drawing. When the discharge pressure of the variable displacement pump 1 becomes less than P2 shown in FIG.
Is pushed over and the piston 47 is slid so that the oil chamber 53 decreases. On the other hand, a pin 57 is provided on the wall surface of the insertion hole 45 forming the oil chamber 51 so that the displacement of the variable displacement pump 1 does not fall below a predetermined volume due to the sliding of the piston 47 when the discharge pressure is P2 or higher. An actuator 61 is fixed to the axial end surface forming the oil chamber 53, and extends into the oil chamber 31 by loosely inserting a hole 62 in the wall surface of the body 25. When the volume of the oil chamber 53 is maximum, its tip does not come into contact with the spool 15, but comes into contact with it when the volume becomes less than a predetermined volume, and the spring 4
The pressing force of 9 pushes the spool 15 in a direction to reduce the communication opening degree between the supply port 27 and the output port 29.

The pressure compensating portion 13 has a cylindrical insertion hole 67 along the longitudinal direction in the body 61, and the spool 63 can slide in the insertion hole 67 in the axial direction. .. A supply port 55 communicating with the insertion hole 67 and an output port 91 are formed in the body 61 at predetermined positions. The output port 91 communicates with the supply port 27.

The spool 63 has lands 63a and 63b formed at both ends thereof and an annular groove 6 formed at the center thereof.
3c and the rightmost side in the figure, the supply port 5
5 and the output port 91 have the maximum communication opening, and the communication opening decreases when moving to the left in the figure.

Also, facing both ends in the axial direction of the spool 63,
The end surface pressure chambers 71 and 73 are respectively formed, and the end surface pressure chamber 71
Further, a spring 65 having a predetermined spring constant is inserted to press the spool 63 in a direction of decreasing the communication opening degree between the supply port 55 and the output port 91.

Further, the output port 29 and the end surface pressure chamber 71
Is communicated with an oil passage 99, and the output port 91 and the end surface pressure chamber 73 are communicated with an oil passage 97.

With the above configuration, when the discharge pressure P and the discharge flow rate Q of the variable displacement pump 1 are balanced within the section A shown in FIG. 3, the flow rate control valve 8 controls the flow rate according to the command value of the controller 7. Can be supplied to the cooling fan hydraulic motor 2, and a required flow rate can be supplied to the hydraulic suspension actuators 5a to 5d via the pressure control valve. At this time, the pressure compensating unit 13 can supply a constant flow rate by keeping the pressure difference between the supply port 27 and the output port 29 of the flow rate control unit 11 constant regardless of the load of the cooling fan hydraulic motor 2.

The hydraulic suspension actuators 5a to 5d are normally driven by the hydraulic pressure controlled by the pressure control valve 3. At this time, since the pressure equal to or higher than the discharge pressure P2 is acting on the oil chamber 53 of the restriction valve 19, the piston 47 is pressed leftward in the drawing, and its position does not change.

When the actuators 2, 5a to 5d require a large amount of hydraulic oil at the same time and cannot balance in the section A shown in FIG. 3, the discharge pressure P of the variable displacement pump 1 becomes a predetermined value P2 or less, and the restriction valve 1 and 2, the force for pushing the piston 47 to the left in FIG. 1 and FIG. 2 is reduced, and the force pushing the piston 47 to the right in the drawings is overcome by the spring 49, so that the piston 47 moves to the right in the drawings. When the piston 47 moves by a predetermined value or more, the actuator 61 comes into contact with the end surface of the spool 15 to move the spool 15 to the right in the figure, and as a result, the communication between the supply port 27 and the output port 29 is restricted.
Therefore, the amount of hydraulic oil supplied to the cooling fan hydraulic motor 2 is reduced, and the hydraulic oil is supplied to the pressure control valve 3 by that amount. That is, the hydraulic suspension actuators 5a to 5 which are desired to be operated with priority over the cooling fan hydraulic motor 2
Since the amount of hydraulic oil supplied to d can be secured, it can be normally driven and deterioration of the riding comfort of the vehicle can be prevented. Of course during this time, the cooling fan hydraulic motor 2
Although the amount of hydraulic oil supplied to the cooling fan is reduced, the condition in which the hydraulic suspension actuators 5a, 5b, 5c, 5d require the maximum flow rate is momentary, and the supply to the cooling fan hydraulic motor 2 is instantaneous. Since the discharge pressure immediately becomes P2 or more due to the reduction in the amount, the piston 47 returns to the original position, and the engine cooling water does not rise excessively.

As described above, in the present embodiment, a pressure sensor for detecting the discharge pressure of the conventional variable displacement pump is provided, and when it is judged from the detected value that the discharge pressure has decreased to a predetermined value or more, The cost can be reduced because a sensor for detecting the discharge pressure is not required as compared with the case where the supply to the sub-actuator is reduced.

Further, as compared with the conventional one in which a throttle valve is provided in the hydraulic pipe leading to the sub-actuator to reduce the supply to the sub-actuator when the discharge pressure becomes a predetermined value or less, the flow rate control valve is restricted. Since only the valve is provided, space efficiency and installation workability are improved and cost can be reduced.

In the present embodiment, the variable displacement pump is used as the hydraulic pump, but the hydraulic pump is not limited to this, and a fixed displacement pump may be used.

Further, in this embodiment, the hydraulic suspension actuator is used as the main actuator and the cooling fan hydraulic motor is used as the auxiliary actuator, but it is needless to say that the present invention can be applied to any hydraulic control system. .. Furthermore, each of the main actuator and the sub-actuator may be composed of a plurality of actuator groups. In short, it suffices to provide a flow rate control valve having a restriction valve that operates due to a decrease in hydraulic pressure in the hydraulic piping leading to the actuator with a lower priority. The flow control valve may have a rotary type spool.

Although a piston is used as the pressing member,
However, the present invention is not limited to this, and any device that can press the spool when the discharge pressure is reduced may be used.

[0034]

As described above, in the hydraulic control device of the present invention, when the discharge amount of the hydraulic pump becomes close to the limit discharge amount and the discharge pressure becomes equal to or less than the predetermined value, the pressing member provided with the restriction valve is provided. Causes the spool to operate so as to limit the flow rate to the sub-actuator, suppresses the decrease in the amount of hydraulic oil supplied to the main actuator that you want to operate preferentially, and supplies a sufficient amount of hydraulic oil. The energy saving effect of the system integration can be satisfied, and the performance of multiple actuators can be prevented from decreasing at the same time. The discharge pressure is detected using the conventional pressure sensor, and the flow rate is controlled according to the detected value. The flow rate of the valve was controlled, and a throttle valve was installed in the hydraulic pipe to the sub-actuator to reduce the supply of hydraulic oil to the sub-actuator when the discharge pressure dropped. It reduces the cost compared to, it is possible to improve the space efficiency and mounting workability.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a vehicle hydraulic control device that is an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the flow control valve shown in FIG.

FIG. 3 is a graph showing a relationship between a discharge pressure P and a discharge flow rate Q.

FIG. 4 is a configuration diagram of a conventional vehicle hydraulic control device.

[Explanation of symbols]

1 ... Variable displacement pump (hydraulic pump), 2 ... Cooling fan hydraulic motor (auxiliary actuator), 5a to 5d ... Hydraulic suspension actuator (main actuator), 8 ... Flow control valve, 15 ... Spool, 19 ... Limit Valve, 47 ... Piston (pressing member).

Claims (1)

[Claims] 1. A hydraulic pump for supplying hydraulic oil, a main actuator and a sub-actuator driven by the hydraulic oil distributed from the hydraulic pump, and a hydraulic pump provided between the hydraulic pump and the sub-actuator. A hydraulic control device comprising: a flow rate control valve having a spool for changing a flow rate of hydraulic oil supplied to the sub-actuator; a hydraulic pressure control device including a pressing member for exerting a hydraulic pump discharge pressure, the discharge pressure being lower than a predetermined value. The hydraulic control device is characterized in that a pressing valve is provided with a limiting valve that operates the spool in a direction to reduce the flow rate of the supply to the sub-actuator.