JPH059525Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a directional flow control valve for controlling a hydraulic cylinder constituting an active suspension of a vehicle.

(Prior Art) Conventionally, when controlling the position of a double-acting hydraulic cylinder a of an active suspension as shown in FIG. A directional flow rate control valve d having the structure shown in is provided, and the spool g of the valve d strokes in accordance with the strength of the current value input from the calculator f to the proportional solenoids e, e of the valve d. The direction and flow rate of the flow are controlled by making the opening area of the valve d, that is, the area of the flow rate control orifice, proportional to the current flow. In this case, signals from accelerometers j, load cells k, displacement sensors l, etc. installed on the sprung mass h and unsprung mass i of the vehicle are input to the computing unit f, and the signals are inputted to the computing unit f to match the vehicle condition. the valve d
The hydraulic cylinder a is controlled by the hydraulic cylinder a.

(Problem to be solved by the invention) The opening area of the above-mentioned directional flow control valve d can be set in proportion to the current value to the proportional solenoids e, but the flow rate changes depending on the difference between the pump pressure and the load pressure. Depending on the situation, it may change in various ways as shown in the third diagram.
There is a disadvantage that it is difficult to obtain stability of the suspension system. These inconveniences can be solved by connecting a pressure compensating valve O equipped with a spool n operated by the differential pressure between the pump pressure and the pressure of the hydraulic cylinder a extracted by the shuttle valve m as shown in the fourth figure to the pump circuit as shown in the fifth figure. Although this can be solved by providing the pressure compensation valve O and the directional flow rate control valve d, this is not suitable for use in vehicles that have strong demands for downsizing and compactness.

Also, the hydraulic cylinder a for suspension is the first
It is better to use a single-acting type as shown in Figure 6 than a double-acting type as shown in the figure because the number of hydraulic circuits is smaller and it is preferable for vehicles, but the flow to cylinder a is in the reciprocating direction. Therefore, in this case, it is necessary to provide two pressure compensating valves O, which is inappropriate from the viewpoint of miniaturization and compactness.

The object of the present invention is to solve the above-mentioned inadequacies when a single-acting type hydraulic cylinder is used as an active suspension hydraulic cylinder.

(Means for Solving the Problems) In order to achieve the above object, the present invention uses a spring to spring both ends of a spool slidably provided in the valve housing to hold the spool in a neutral position and to A movable member of a proportional solenoid is connected to each end, and the spool is slid by a distance depending on the magnitude of an electric signal to the proportional solenoid to allow fluid to flow in and out of a single-acting hydraulic cylinder of an active suspension. In the valve housing, a pump port connected to the hydraulic pump, a tank port connected to the tank, and two first and second cylinder ports connected to the hydraulic cylinder are formed in the valve housing. a first flow control orifice formed by a valve housing and a spool, and a first flow control orifice formed by a valve housing and a spool;
a first passage connecting to a cylinder port, and a second passage connecting the second cylinder port to a tank port through a second flow control orifice formed by a valve housing and the spool when the spool slides in the opposite direction. a first passage, which is actuated by a pressure difference before and after a first flow control orifice in the first passage to change the area of the first passage and control the pressure difference as constant as possible; A second compensator is provided with a compensator spool, and is operated by a pressure difference before and after a second flow control orifice in the second passage to change the area of the second passage and control the pressure difference to be as constant as possible. Added a spool.

(Function) When an electric signal is input to one proportional solenoid of the directional flow control valve, the spool of the directional flow control valve slides a distance corresponding to the magnitude of the electric signal, and for example, the pump port and the first cylinder port are moved. The valve housing and the sliding spool are connected via a first flow control orifice, and pressurized fluid flows from the hydraulic pump into the single-acting hydraulic cylinder for the active suspension, causing the active suspension to elongate. Given. In this case, the opening area of the first flow control orifice is a predetermined area, but the differential pressure between the pressure inside the hydraulic cylinder and the pressure of the hydraulic pump varies depending on the conditions such as the load on the vehicle and the speed. In order to keep the flow rate flowing through the first flow control orifice constant and to stably control the suspension, it is necessary to keep the differential pressure across the orifice constant. Therefore, when the differential pressure is larger than a predetermined value, the first compensator spool provided in the first passage connecting the pump port and the first cylinder port in the spool narrows the area of the first passage, and the differential pressure becomes small. The area of the first passage is expanded, the differential pressure before and after the orifice is controlled to be as constant as possible, and the flow rate through this or the flow rate flowing into the hydraulic cylinder is controlled to be constant.

Also, when an electric signal is input to the other proportional solenoid of the directional flow control valve, the spool slides a distance according to this signal, connecting the second cylinder port and tank port via the second flow control orifice. . In this case as well, a second compensator spool provided in a second passage connecting the second cylinder port and the tank port operates to vary the area of the second passage in accordance with changes in the differential pressure of the second flow control orifice; When the pressure difference is larger than a predetermined value, the area of the second passage is narrowed, and when it is smaller, the area is widened, and the pressure difference across the second flow rate control orifice is controlled to be constant, thereby controlling the passing flow rate to be constant.

The directional flow control valve compensates the pressure of the fluid flowing back and forth to the single-acting hydraulic cylinder of the active suspension using the two internal compensator spools, so there is no need to provide a separate pressure compensation valve, making it compact. An active suspension control device can be constructed at low cost.

(Example) To explain the example of the present invention with reference to attached drawings,
In Fig. 7, numeral 1 is a single-acting hydraulic cylinder of the active suspension, and 2 is a hydraulic pump 3.
A directional flow control valve is shown for supplying discharge fluid to the hydraulic cylinder 1 or discharging it from the hydraulic cylinder 1 to the tank 4. An example of the configuration of the directional flow rate control valve 2 is as shown in FIG. 8, in which both ends of a spool 6 slidably provided in the valve housing 5 are resiliently urged by springs 7 and 8, respectively, to neutralize the spool 6. A movable member 9 of proportional solenoids 9 and 10 is provided at both ends to hold the movable member 9 in position.
a, 10a are connected, and the spool 6 slides to the switching position by a distance corresponding to the magnitude of the electrical signal, eg, current value, to the solenoids 9, 10. Spool 6
A pump port 11 consisting of an annular hole, a first cylinder port 12, a tank port 13 and a second cylinder port 14 are sequentially formed in the valve housing 5 around the pump port 11. 13 is connected to the tank 4, and the first and second cylinder ports 12 and 14 are connected to the hydraulic cylinder 1, respectively. 15 is a first passage formed in the spool 6 to connect the pump port 11 to the cylinder port 13; 16 is a second passage formed in the spool 6 to connect the second cylinder port 14 to the tank port 13; Show the passage.

The first passage 15 includes a circular hole 17 in the axial direction of the spool 6, an inlet 18 that extends from the circular hole 17 in the radial direction and constantly communicates with the pump port 11 regardless of the sliding movement of the spool 6; An outlet 19 extends radially from the circular hole 17 and communicates with the first cylinder port 12 when the spool 6 slides in one direction, and when the outlet 19 communicates with the first cylinder port 12. The outlet 19 of the spool 6 and the valve housing constitute a first flow rate control orifice 20 that changes depending on the sliding distance of the spool 6. The second passage 16 also includes a circular hole 2 in the axial direction of the spool.
1, an inlet 22 extending in the radial direction from the circular hole 21 and constantly communicating with the second cylinder port 14 regardless of the sliding movement of the spool 6; an outflow port 23 that communicates with the tank port 13 when sliding in the direction, and when the outflow port 23 communicates with the tank port 13, the spool 6 slides between the outflow port 23 of the spool 6 and the valve housing 5. The second flow rate control orifice 24 is configured to change depending on the moving distance.

A first compensator spool 25 is slidably accommodated in the circular hole 17 of the spool 6. The compensator spool 25 has a land portion 26 that gradually narrows the inlet 18 by sliding, and a first flow rate control device. The pressure upstream of the orifice 20 is applied to one end surface 25 of the compensator spool 25.
An introduction hole 27 leading to a is formed. The other end surface 25b of the compensator spool 25
is configured such that the force of the compensator spring 28 and the pressure downstream of the first flow control orifice 20 introduced through the introduction hole 29 provided in the spool 6 act on the spool 6 and the pump port 11. When the first cylinder port 12 is slid to connect, the compensator spool 25 operates so that the differential pressure across the first flow control orifice 20 becomes constant. Specifically, when the differential pressure is larger than a set value, the compensator spool 25 is moved by deflecting the compensator spool 28,
Also, if it is smaller than the set value, it will move in the opposite direction,
The land portion 26 narrows or widens the inlet 18 to narrow or widen the area of the first passage 15, thereby controlling the differential pressure as constant as possible, and controlling the flow rate flowing through the first flow rate control orifice 20 according to its opening area. It is fixed according to

30 is a circular hole 21 in the second passage 16 of the spool 6.
A second compensator spool 30 is slidably accommodated in the second compensator spool 30, and the second compensator spool 30 forms a land portion 21 that gradually narrows the inlet 22 by sliding, and also controls the pressure upstream of the second flow rate control orifice 24. An introduction hole 32 leading to one end surface 30a of the second compensator spool 30 is formed. The force of the compensator spring 33 and the downstream pressure of the second flow rate control orifice 24 introduced through the introduction hole 34 provided in the spool 6 act on the other end surface 30b of the second compensator spool 30. When the spool 6 slides to connect the second cylinder port, the second compensator spool 30 operates so that the differential pressure across the second flow control orifice 24 becomes constant. Specifically, when the differential pressure is larger than the set value, the compensator spring 33 is bent and the second compensator spool 30 is
moves, and if it is smaller than the set value, it moves in the opposite direction, and the land portion 31 narrows or widens the inlet 22, narrowing or widening the area of the second passage 16, and reducing the differential pressure as much as possible. is controlled at a constant level,
The flow rate flowing through the second flow rate control orifice 24 is made constant according to its opening area.

In Figure 7, 34 is the neutral position, 35, 36
numeral 38 represents a switching position, and numeral 38 represents an arithmetic unit substantially similar to the conventional example, which outputs an electric signal to the proportional solenoids 9 and 10.

To explain the operation of the device of the above embodiment, when an electric signal of a certain magnitude is input from the calculator 38 to one proportional solenoid 9, the movable member 9a moves the spool 6 by a distance corresponding to the magnitude of the electric signal. Slide the pump port 11 and the first cylinder port 12
are in communication via a first passage 15, and supply pressure fluid from the hydraulic pump 3 to the hydraulic cylinder 1 of the active suspension. In this case, the pressure fluid flows through the first fluid control orifice 20, but when the differential pressure across the orifice 20 increases or decreases from the set value, the first compensator spool 25 slides in balance with the compensator spring 28, Since the pressure difference is controlled to be constant by changing the area of the first passage 15, the opening area of the first flow rate control orifice 20 is controlled regardless of the difference between the pressure of the hydraulic cylinder 1 and the pressure of the hydraulic pump 3. A constant flow rate proportional to 1 can be flowed to the cylinder 1, and a hydraulic circuit for an active suspension can be constructed compactly without providing a separate pressure compensation valve.

Also, the electric signal is connected to the other proportional solenoid 10.
, the spool 6 slides to connect the second cylinder port 14 and the tank port 13 via the second passage 16, and in this case, the second compensator 30 adjusts the difference before and after the second flow control orifice 24. It operates to keep the pressure constant and controls the flow rate from the second cylinder port 14 to the tank port 13 to be constant. As a result, the flow rate flowing from the hydraulic cylinder 1 of the active suspension to the tank can be controlled at a constant level without the need for a separate pressure compensation valve, and the active suspension system can operate at a constant level regardless of the mass it supports. .

(Effect of the invention) As described above, according to the present invention, a pump port, a tank port, and first and second cylinder ports are formed in the valve housing of a directional flow control valve for an active suspension operated by a proportional solenoid. death,
When sliding onto the spool of the directional flow control valve, the pump port is connected to the first through the first flow control orifice.
A first passage connecting to the cylinder port and a second passage connecting the second cylinder port to the tank port via a second flow control orifice are formed, and each of the first and second passages has a first passage and a second passage, respectively. Since the compensator spool is provided, the differential pressure between each of the first and second flow control orifices can be controlled to be constant, and the flow rate flowing back and forth through the directional flow control valve can be controlled without providing a separate pressure compensation valve. Since the hydraulic cylinders of the active suspension can be controlled accurately, it is possible to control the hydraulic cylinders of the active suspension with a compact device, and it is advantageous for controlling single-acting hydraulic cylinders with a small number of hydraulic circuits.

[Brief explanation of drawings]

Fig. 1 is a diagram of a conventional active suspension, Fig. 2 is a specific sectional view of the directional flow control valve shown in Fig. 1, and Fig. 3 shows the relationship between current value and flow rate of the conventional directional flow control valve. Figure 4 is a sectional view of a conventional pressure compensation valve, Figure 5 is a diagram when the pressure compensation valve shown in Figure 4 is installed in the active suspension shown in Figure 1, and Figure 6 is a single acting type. FIG. 7 is a diagram of the embodiment of the present invention, and FIG. 8 is a sectional view of a specific example of the directional flow control valve shown in FIG. 7. 1... Single-acting hydraulic cylinder, 2... Directional flow control valve, 3... Hydraulic pump, 4... Tank, 5...
... Valve housing, 6... Spool, 7, 8... Spring, 9,
10... Proportional solenoid, 9a, 10a... Movable member, 11... Pump port, 12... First cylinder port, 13... Tank port, 14... Second cylinder port, 15... First passage, 16 ……
Second passage, 20...First flow control orifice, 2
4...Second flow rate control orifice, 25...First compensator spool, 30...Second compensator spool.

Claims (1)

[Scope of utility model registration request] Both ends of a spool, which is slidably provided in the valve housing, are held in a neutral position by springing both ends of the spool, and movable members of a proportional solenoid are connected to each end of the spool, and the spool is connected to an electric current to the proportional solenoid. In a valve housing that controls the flow rate and flow of fluid into a single-acting hydraulic cylinder of an active suspension by sliding a distance depending on the magnitude of a signal, a hydraulic pump is attached to the valve housing. A pump port that is connected to the tank, a tank port that is connected to the tank, and two first and second cylinder ports that are connected to the hydraulic cylinder are formed in the spool. A first passageway connected to the first cylinder port via a first flow control orifice formed by the valve housing and the spool, and a first passage connecting the second cylinder port to the valve housing and the spool when the spool slides in the opposite direction. a second passageway connected to the tank port via a second flow rate control orifice formed by the flow control orifice; A first compensator spool is provided in the second passage to change the pressure difference and control the differential pressure to be as constant as possible, and the second passage is operated by the pressure difference before and after the second flow control orifice to control the area of the second passage. A directional flow control valve for an active suspension, characterized in that a second compensator spool is provided for controlling the differential pressure to be as constant as possible by changing the pressure difference.