JPH0654124B2 - Electric one-liquid pressure controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is an improvement of an electro-hydraulic control device for converting an electric control signal into a hydraulic pressure and controlling the swash plate of a variable displacement pump with the hydraulic pressure. More specifically, the present invention relates to a device that does not require a nozzle-flapper mechanism.

(Prior Art) Generally, this type of electro-hydraulic pressure control device is provided with a nozzle-flapper mechanism as a mechanism for converting a displacement generated in a torque motor into hydraulic pressure. As shown in FIG. 7, this is composed of a flapper (a) of a torque motor and a pair of nozzles (b) whose tip portions face each other with a small gap t, t on the left and right sides of the flapper (a), respectively. Consists of (b) and
The nozzles (b) and (b) and the fixed orifices (d) and (d) provided in the oil supply passages (c) and (c) respectively communicate with both ends of the guide valve spool (e). At the same time, pressure oil is supplied to the nozzles (b) and (b) through the fixed orifices (d) and (d), and the flapper (a) is at a neutral position with respect to both nozzles (b) and (b). , The back pressures of both nozzles are balanced so that the spool (e) is positioned at the neutral position, and when the flapper (a) is slightly displaced toward one side, both nozzles are changed due to changes in the minute gaps t and t. When a differential pressure is generated between the back pressures, the spool (e) is moved by this differential pressure. (See US Pat. No. 3,065,735, drawings, etc.).

(Problems to be Solved by the Invention) However, in the above-mentioned conventional one, both nozzles (b),
The nozzle diameter of (b) is usually a small diameter of 1 mm or less. Therefore, there is a drawback in that it is easily affected by dust and the like, and it is necessary to manage dust sufficiently. Also,
The amount of displacement of the flapper (a) is within the range of the minute gaps t, t between the nozzles (b) and (b), and there is a drawback that precision is required and the cost is high.

The present invention has been made in view of the above point, and an object thereof is to convert an electric control signal into hydraulic pressure without using a nozzle-flapper mechanism and use the hydraulic pressure to swash plate of a variable displacement pump, etc. By controlling the unidirectional movement in one direction, the movement of the spool can be surely and accurately controlled even when dust or the like adheres, and the cost can be reduced.

(Means for Solving the Problems) In order to achieve the above object, the present invention uses a proportional solenoid to directly control the movement of the spool.

That is, the concrete solution of the present invention is slidably fitted in the valve body (1) having the pump port (4a), the cylinder port (4b) and the tank port (4c) as shown in the drawings. A spool (5) for switching the cylinder port (4b) between the pump port (4a) and the tank port (4c) and a force proportional to the value of the input signal connected to one end of the spool (5). There is provided an electro-hydraulic control valve (A) having a proportional solenoid (3) for generating and a spring (11) arranged at the other end of the spool (5). Further, the cylinder port (4) of the valve body (1) is
b) a variable displacement pump (B) having a controlled body (15) such as a swash plate that receives a force by a cylinder (7) communicating with b), and a controlled body of the variable displacement pump (B) (1
5) A moving amount detecting means (17) for detecting the moving amount, and a correction circuit (18) for comparing and subtracting an actual moving amount signal of the moving amount detecting means (17) with an input target amount signal. The output of the correction circuit (18) is input to the proportional solenoid (3) of the electro-hydraulic pressure control valve (A), and the controlled body (15) of the variable displacement pump (B) is A force proportional to the deviation between the actual movement amount and the target movement amount is generated in the proportional solenoid (3), and the generated force directly moves the spool (5) of the electro-hydraulic pressure control valve (A). It is a thing.

(Operation) According to the present invention, in the present invention, when the controlled body (15) of the variable displacement pump (B) is in the upright state and its actual movement amount is zero, the proportional solenoid (3) is Since an output equal to the value of the target amount signal is received from the correction circuit (18), the proportional solenoid (3) generates a force corresponding to the value of the target amount signal to generate a spring (11) at the other end of the spool (5). Move until it equilibrates with the urging force of. For this reason,
When the spool (5) moves and the cylinder port (4b) communicates with the pump port (4a), supply of hydraulic pressure to the controlled body (15) of the variable displacement pump (B) is started, The controlled body (15) begins to tilt greatly. In that case, the movement amount of the controlled body (15) is detected by the movement amount detecting means (17), and the target amount signal is subtracted and corrected in the correction circuit (18) according to the increase of the movement amount. Since the output of the circuit (18) gradually decreases, the force generated by the proportional solenoid (3) and the force gradually decrease, and the spool (5) slides in the opposite direction to the cylinder port (4b). When the communication area with the pump port (4a) is gradually reduced and the communication is eventually cut off, the controlled body (15) is controlled to a position corresponding to the value of the target amount signal.

On the other hand, when the controlled body (15) controlled to the target position corresponding to the target amount signal as described above is controlled to the target position smaller than the target position, the target input to the correction circuit (18) Since the quantity signal becomes a small value and the generated force of the proportional solenoid (3) decreases, the spool (5) is moved by the spring (11) at the other end, and this time, the cylinder port (4b) and the tank port (4c). ) And the communication area is increased, and the controlled body (15) has a gradually smaller inclination angle. With the operation of the controlled body (15), the output of the correction circuit (18) gradually becomes large, so that the generated force of the proportional solenoid (3) increases, and the spool (5) becomes Moves in the opposite direction and the communication area between the cylinder port (4b) and the tank port (4c) gradually becomes smaller, and when the communication is eventually cut off, the controlled body (15) becomes smaller as described above. The target position is controlled according to the value of the target amount signal.

Here, in feedback control of the movement amount of the controlled body (15) of the variable displacement pump (B), a proportional solenoid (3) is used instead of the conventional nozzle-flapper mechanism,
Since the spool (5) of the electro-hydraulic pressure control valve (A) is directly moved by the generated force of the proportional solenoid (3), the conventional nozzle-flapper mechanism is not required and strict management of dust is not required. In addition, the electric-hydraulic pressure control device can be constructed at low cost.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing.

1 and 2 show an electro-hydraulic control device according to the present invention. In FIG. 1 and FIG. 2, (A) is electric-
A hydraulic control valve, wherein in the electro-hydraulic control valve (A), (1) is a valve body, and inside the valve body (1) is a central axis direction (left and right direction in the drawing). A proportional solenoid having a first cavity (2) extending to the first cavity (2) and a rod (3a) facing the first cavity (2) at the left end of the valve body (1) in the figure. (3) is provided. The proportional solenoid (3) is a variable displacement pump (B) described later.
The rod (3a) is expanded and contracted in response to the output of the correction circuit (18) that receives the target amount signal for positioning the controlled body (15) such as the swash plate at the target position. As shown in the figure, the force F for extending the rod (3a) increases in proportion to the increase in the received control signal value i (that is, the output of the correction circuit (18)).

A sleeve (4) is slidably fitted in the first space (2) of the valve body (1) in the left-right direction in the drawing, and a spool is provided in the sleeve (4). (5) is slidably fitted in the left-right direction in the figure. A fluid pump (6) is provided at approximately the center of the sleeve (4) in the sliding direction.
And a variable displacement pump (B) located on the right side of the pump port (4a) in the figure.
The cylinder port (4b) communicating with the cylinder (7) that rotates the controlled body (15) constituted by the swash plate in the clockwise direction in the figure is opposite to the pump port (4a) of the cylinder port (4b). A tank port (4c) located on the side and opened to a tank (not shown) is provided. Further, the sleeve (4) has one end portion (right end portion in the figure).
Is urged to the left in FIG. 1 by a positioning spring (8) which is compressed between the main body cover (10) and the other end (left end in the figure) of the sleeve (4),
The neutral position adjusting mechanism (2) faces the second space (9) which is formed in the radial direction of the valve body (1) and whose lower portion is largely opened.
0) It is brought into contact with and engaged with the rear end portion and positioned at a predetermined position. On the other hand, the spool (5) has its left end in the figure connected to the tip of the rod (3a) of the proportional solenoid (3), and the right end in the figure of the spool (5) is the spool (5). ) Is urged in the left direction in the figure by a spring (11) which is contracted between the right end and the main body cover (10). Therefore, when the spool (5) is not controlled to move by the proportional solenoid (3), the spool (5) is positioned at the neutral position shown by the spring (11) at the right end of the spool (5), and the spool (5) is moved to the left end position (hereinafter, the neutral position). The spool (5) in the neutral position blocks the communication between the pump port (4a) and the cylinder port (4b), and also connects the cylinder port (4b) and the tank port (4a). To do. On the other hand, when the proportional solenoid (3) receives the target amount signal, the extension movement of the rod (3a) moves the spool (5) from the neutral position to the right in FIG. After moving the amount, the pump port (4a) is communicated with the cylinder port (4b).

Further, in the second space (9), a feedback link (1) in which the lower part of the central part extends downward from the opening part
2) is provided, and the feedback link (12) is rotatably supported on an intermediate shaft (13) rotatably provided on the valve body (1) at its upper portion, as shown in FIG. The feedback link (12) is connected via a connecting rod (14) to a controlled body (15) which is a swash plate of a variable displacement pump operated by the cylinder (7) through a connecting rod (14). Further, the intermediate shaft (13) is connected to the potentiometer (16), so that the controlled body (15) rotates from the upright state around the fulcrum (15a) in the clockwise direction in FIG. 1 or in the clockwise direction. When it rotates counterclockwise toward the upright direction after the rotation, the movement of the connecting rod (1
4), feedback link (12) and intermediate shaft (1
A movement amount detecting means (17) which transmits the movement amount to the potentiometer (16) via 3), detects the movement amount by the potentiometer (16), and generates an actual movement amount signal.
Are configured.

Further, as shown in FIG. 1, the movement amount detecting means (1
The actual movement amount signal of 7) is output to the correction circuit (18). The correction circuit (18) receives a target amount signal for positioning the controlled body (15) at a target position, compares and subtracts the target amount signal with the actual movement amount signal from the movement amount detecting means (17). A difference signal corresponding to the difference is generated, and the difference signal is output to the proportional solenoid (3) as the control signal i. Therefore, the target amount signal is obtained from the actual movement amount signal of the movement amount detecting means (17). It is configured to perform comparison and subtraction for correction.

As shown in FIG. 2, the valve body (1) is provided with an auxiliary manual mechanism (30) for manually controlling the movement of the spool (5) when the proportional solenoid (3) fails. The auxiliary manual mechanism (30) is fitted with a fitting member (31) rotatably fitted and supported on the valve body (1), and is pinned to the front end of the fitting member (31) as shown in FIG. Fulcrum (32a) as shown
An operating lever (3
2) and a projecting pin (33) (3rd) which is eccentrically planted at the rear end of the fitting member (31) and is disposed in the second cavity (9) close to the spool (5). (See figure) and
By rotating the operation lever (32), the fitting member (3
1) is rotated to move the projecting pin (33) in the left-right direction in FIG. 2, so that the projecting pin (33) is brought into abutting engagement with the spool (5) to move the spool (5) left and right in FIG. The movement is controlled in the direction. The protruding pin (33) of the auxiliary manual mechanism (30) and the protruding pin (33)
Land (5a) of the spool (5) located on both sides of the
(5b), the maximum amount of movement of the spool (5) by the operation of the proportional solenoid (3) (for example, 3mm)
The above gap is provided so that the auxiliary manual mechanism (30) is not driven by the movement of the spool (5) under the electric control.

Further, the neutral position adjusting mechanism (20) includes the spool (5).
For adjusting the neutral position of the sleeve (4) (adjustment of the amount of play on the left and right), and the structure thereof includes a fitting member (21) rotatably fitted and supported on the valve body (1), Adjustment screw (22) provided at the front end of the fitting member (21)
The fitting member (21) has a rear end portion formed to have a small diameter and to be eccentric with respect to the central portion as shown in FIG. By rotating the fitting member (21) to move the rear end portion in the left-right direction in FIG. 2, the sleeve (4) is moved in the left-right direction in FIG. 2 via the cushioning member (23), and the spool is moved. (5) The neutral position is adjusted (the left and right play amount of the spool (5) is adjusted).

Next, the operation of the above embodiment will be described. When the controlled body (15) of the variable displacement pump (B) is in the upright state, the proportional solenoid (3) causes the correction circuit (1) to operate.
8), when the output (control signal i) is not received, the spool (5) has the spring (1) at the right end in FIG.
It is positioned at a neutral position where the pump port (4a) and the cylinder port (4b) are closed by the urging force of 1) and the cylinder port (4b) and the tank port (4c) are opened. Therefore, the cylinder (7) is opened to the tank, and the upright state of the controlled body (15) is formed.

Now, when a target amount signal (for example, 1500 mA) corresponding to the target tilt angle of the controlled body (15) is input to the correction circuit (18), the value of this target amount signal is directly input to the proportional solenoid (3). The control signal i is input, and in the proportional solenoid (3), a force Fo proportional to the control signal value (for example, io) is generated based on the characteristic of FIG. 5, and the rod (3a) expands and moves. The extension movement of the rod (3a) causes the spool (5) to start moving rightward in FIG. Then, a predetermined play amount until the spool (5) blocks communication between the cylinder port (4b) and the tank port (4c) (value of the control signal i required to move the spool (5) by the predetermined play amount) Is, for example, 500m as shown in Fig. 6.
After moving (A), the pump port (4a) is connected to the cylinder port (4b), and the pressing force Fo of the rod (3a) and the spring on the right side in FIG. It stops at a position where the urging force of (11) is balanced. As a result, the flow rate according to the opening area of the cylinder port (4b) is supplied from the fluid pump (6) to the cylinder (7), and the controlled body (15) of the variable displacement pump (B) causes the spool ( From the time when 5) begins to move beyond the predetermined play amount, the first point centered on the fulcrum (15a)
It starts to rotate clockwise at a relatively high speed.

Then, as the controlled body (15) rotates,
The movement is the connecting rod (15), the feedback link (1
2) and transmitted to the potentiometer (16) via the intermediate shaft (13), the actual movement amount is continuously detected by the potentiometer (16), and is output to the correction circuit (18) as an actual movement amount signal. . As a result, in the correction circuit (18), the target amount signal is corrected to be smaller by the value of the gradually increasing actual movement amount signal, and the control signal i becomes gradually smaller, which causes a decrease in this signal value. In proportion to this, the rod pressing force of the proportional solenoid (3) gradually decreases. As a result, the spool (5) gradually returns to the left in FIG. 1 in order to balance with the urging force of the spring (11) on the right in FIG. 1, and the opening area of the cylinder port (4b) decreases, so that the cylinder The flow rate to (7) gradually decreases, and the rotational speed of the controlled body (15) gradually decreases. And
When the controlled body (15) rotates to the target tilt angle, the spool (5) blocks the communication between the pump port (4a) and the cylinder port (4b), so that the controlled body (15) moves to the target tilt angle. Will be controlled by holding. At this time, since the spool (5) is at a position where the predetermined play amount is moved from the neutral position, the value of the output (control signal i) of the correction circuit (18) is the output value required to move the predetermined play amount. (500mA, so the actual travel signal value is 1000m
A.

Further, as described above, the controlled object (1
When 5) is rotated counterclockwise toward its upright direction this time, the value of the target amount signal input to the correction circuit (18) becomes a small value (for example, 1500 mA to 1000 mA).
As a result, the control signal i output from the correction circuit (18)
The value of changes from 500mA to zero, and the force generated by the proportional solenoid (3) becomes zero. This allows the spool (5)
Is urged by a spring (11) on the right side of the cylinder and moves to the left in FIG. 1, and the cylinder port (4b) communicates with the tank port (4c). As a result, the oil supplied to the cylinder (7) begins to be discharged, the controlled body (15) of the variable displacement pump (B) begins to rotate counterclockwise in FIG. 1, and the inclination angle becomes smaller. Then, as the actual movement amount signal input to the correction circuit (18) gradually decreases, the output (control signal i) of the correction circuit (18) gradually increases and the rod pressing force of the proportional solenoid (3) increases. Since the spool (5) gradually increases, the spool (5) gradually moves to the left in FIG. 1, the opening area of the cylinder port (4b) and the tank port (4c) decreases, and the controlled body (15) tilts. When rotated to the angle, the spool (5) blocks communication between the cylinder port (4b) and the tank port (4c), so that the controlled body (15) is held and controlled at the target tilt angle. At this time, since the spool (5) is located at a position where the predetermined play amount is moved from the neutral position, the value of the output (control signal i) of the correction circuit (18) is the same as the above value when the predetermined play amount is moved. Output value required (500mA)
And the actual movement amount signal value is 500 mA.

In the above case, the tilt angle of the controlled body (15) is proportional to the amount of movement of the spool (5) to the right or left in FIG. 1, and this amount of movement corresponds to the rod pressing force of the proportional solenoid (3). Since they are proportional to each other, the tilt angle of the controlled body (15) eventually becomes an angle proportional to the value of the target amount signal input to the correction circuit (18) as shown in FIG. The portion indicated by (X) in FIG. 6 is a portion corresponding to the play amount of the movement of the spool (5), and the value of the target amount signal is, for example, 500 mA as described above.
When the target amount signal is 500 mA or less, the controlled body (15) is in the upright state and the actual movement amount signal is zero, so the output of the correction circuit (18) (control signal i)
Is 500mA in agreement with this target quantity signal value.

Here, the spool (5) is a proportional solenoid (3)
Since the movement is directly controlled by, the operation does not change even if dust or the like adheres, and strict control of dust and the like can be made unnecessary. Further, a proportional solenoid (3) is provided as a mechanism for controlling the movement of the spool (5).
Is used, the servo valve can be provided at a low cost as compared with the conventional one provided with the nozzle-flapper mechanism. Moreover, the movement control of the spool (5) is direct control by the proportional solenoid (3), and the feedback control of the controlled body (15) is based on the movement amount detecting means (17). ), The servo valve can be made highly responsive by the electric position feedback method which is performed by electrically detecting the servo valve.

In the above embodiment, the sleeve (4) inside the valve body (1)
Although the spool (5) is provided slidably with respect to the above, the spool (5) may be directly slidably provided with respect to the valve body (1).

(Effects of the Invention) As described above, according to the electro-hydraulic pressure control device of the present invention, a proportional solenoid is used when operating a controlled object such as a swash plate of a variable displacement pump. The spool of the electro-hydraulic control valve is directly operated and controlled, and the correction circuit performs subtraction correction between the actual movement amount and the target movement amount of the controlled object of the variable displacement pump, and inputs the deviation signal to the proportional solenoid. So the nozzle-
Electricity that does not require a flapper mechanism, and that electrically controls the controlled object of the variable displacement pump with high response, does not require strict management of dust and is inexpensive and highly responsive and can control operation of the controlled object in one direction. -A hydraulic pressure control device can be provided.

[Brief description of drawings]

1 to 6 show an embodiment of the present invention, FIG. 1 is an overall configuration diagram in the case of performing electrical feedback control of the inclination angle of a swash plate of a variable displacement pump, and FIG. 2 is electro-hydraulic control. A plan view in which a part of the valve is cut away, FIG. 3 is III-III in FIG.
A line sectional view, FIG. 4 is a front enlarged arrow view of the auxiliary manual mechanism, FIG. 5 is a diagram showing force generation characteristics with respect to a reception control signal of a proportional solenoid, and FIG. 6 is a tilt angle of a controlled object with respect to a target amount signal. It is a figure which shows a characteristic. Further, FIG. 7 is a schematic configuration diagram of a nozzle-flapper mechanism showing a conventional example. (A) ... electric-hydraulic control valve, (1) ... valve body,
(3) ... proportional solenoid, (4a) ... pump port, (4b) ... cylinder port, (4c) ... tank port, (5) ... spool, (11) ... spring, (12) ... … Feedback link, (B) …… Variable displacement pump, (15) …… Controlled body, (16) ……
Potentiometer, (17) ... Movement amount detection means, (1
8) ... correction circuit.

Claims (1)

[Claims] 1. A cylinder body having a pump port (4a), a cylinder port (4b) and a tank port (4c) slidably fitted therein.
a spool (5) for switching and connecting b) to a pump port (4a) and a tank port (4c); and a proportional solenoid (5) that is connected to one end of the spool (5) and generates a force proportional to the value of an input signal. 3) and an electro-hydraulic control valve (A) having a spring (11) arranged at the other end of the spool (5) and communicating with the cylinder port (4b) of the valve body (1). A variable displacement pump (B) having a controlled body (15) that swings by receiving a force by a rotating cylinder (7) and a movement amount of the controlled body (15) of the variable displacement pump (B) are detected. Moving amount detecting means (17)
And a correction circuit (18) for comparing and subtracting the actual movement amount signal of the movement amount detecting means (17) and the input target amount signal, and the output of the correction circuit (18) is the electro-hydraulic pressure. The control target (1) of the variable displacement pump (B) is configured to be input to the ratio solenoid (3) of the control valve (A).
A force proportional to the deviation between the actual movement amount and the target movement amount of 5) is generated in the proportional solenoid (3), and the spool (5) of the electro-hydraulic pressure control valve (A) is directly moved by this generated force. An electro-hydraulic pressure control device characterized by the above.