JPH026083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a feedback mechanism in a hydraulic control valve, and in particular, to a feedback mechanism in a hydraulic control valve, which is provided in the middle of a liquid passage and moved in the forward direction by an actuator such as a solenoid or a manual operation mechanism. In a hydraulic control valve equipped with a hydraulic pressure control member that increases the hydraulic pressure in the upstream side of the liquid passage when the liquid is moved in the opposite direction, and decreases the hydraulic pressure when the liquid is moved in the opposite direction, the hydraulic pressure control member This invention relates to a mechanism that feeds back forces related to hydraulic pressure in an upstream portion of a liquid passage.

Prior Art In one type of the above feedback mechanism, an elastic member such as a spring is interposed between a piston operated by hydraulic pressure controlled by a hydraulic pressure control member and the hydraulic pressure control member, and this elastic member There is one that generates an elastic force corresponding to the displacement of the hydraulic pressure control member and feeds it back to the hydraulic pressure control member.

However, a hydraulic pressure control valve equipped with this type of feedback mechanism has the disadvantage that overshoot tends to occur when the hydraulic pressure is suddenly increased. Feedback force on the hydraulic pressure control member does not occur unless the piston moves forward and elastically deforms the elastic member by a certain amount, so if the hydraulic pressure increases rapidly, the feedback force increases accordingly. As a result, the feedback force becomes temporarily too small, causing the hydraulic pressure control member to move beyond the position where it should originally stop, causing the hydraulic pressure to temporarily become higher than the target value.

Purpose of the Invention The present invention has been made against the background of the above circumstances, and therefore, its purpose is to provide a solution that is provided in the middle of a liquid passage and moved in the forward direction by an actuator. In a hydraulic control valve equipped with a hydraulic pressure control member that increases the hydraulic pressure in the upstream side of the liquid passage and decreases the hydraulic pressure when moved in the opposite direction, the hydraulic pressure control member has the hydraulic pressure in the upstream side of the liquid passage. A mechanism that feeds back a force related to the hydraulic pressure in the direction of moving the hydraulic pressure control member in the opposite direction, and prevents or reduces the occurrence of overshoot even when the hydraulic pressure is suddenly increased. The objective is to provide a feedback mechanism for

Structure of the Invention In order to achieve the above object, the feedback mechanism according to the present invention includes (a) a driving piston that receives hydraulic pressure in a first chamber and hydraulic pressure in a second chamber, respectively, on pressure receiving surfaces facing oppositely to each other; (b) connected directly or indirectly to the hydraulic control member of the hydraulic control valve through another member, and
A driven piston receives hydraulic pressure in the third chamber and hydraulic pressure in the fourth chamber, respectively, on pressure receiving surfaces facing oppositely to each other, and (c) the hydraulic pressure is controlled by a hydraulic pressure control valve in a liquid passage in the first chamber. The second chamber communicates with the third chamber, the third chamber communicates with the fourth chamber through a liquid passage with a throttling effect, and the fourth chamber communicates with the liquid pressure of the liquid passage. (d) a means for communicating with a portion downstream of the control valve; and (d) a means provided between the driving piston and the hydraulic pressure control member, which controls the hydraulic pressure control member with an elastic force that changes in response to changes in their relative positions. and an elastic member that biases in the opposite direction.

Functions and Effects of the Invention In the feedback mechanism configured as described above, in a steady state, both the driving piston and the driven piston are stationary, and the elastic force of the elastic member is applied to the hydraulic pressure control member as a feedback force. In the process where the hydraulic pressure is rapidly increased, the driving piston moves forward at high speed, increasing the hydraulic pressure in the second and third chambers, and the force applied to the driven piston due to this increase in hydraulic pressure is applied to the elastic member. This will be applied to the hydraulic pressure control member as a feedback force together with the elastic force of . When the driving piston moves forward, the volume of the second chamber decreases, and the working fluid in the second chamber is pushed out to the third chamber, which is in communication with it, and then from the third chamber to the fourth chamber. However, the communication passage that connects the third and fourth chambers is said to have a throttling effect, so if the forward speed of the driving piston is high, the flow between the second and third chambers will be reduced. When hydraulic pressure is generated and the driving piston is moving forward, and the elastic force of the elastic member has not yet been sufficiently increased, the force based on this hydraulic pressure compensates for the lack of elastic force of the elastic member. This prevents the hydraulic pressure control member from moving beyond its original target value due to a temporary lack of feedback force.

Embodiments Hereinafter, some embodiments of the present invention will be described in detail based on the drawings.

In FIG. 1, reference numeral 10 denotes a housing which is the main body of the hydraulic control valve.For convenience of manufacture, it is divided into two parts, but after assembly, it functions as an integrated housing. This housing 10 has a pressure port 1
2 and a drain port 14 are provided, the pressure port 12 being connected to a pump circuit 20 by a line 18 with a restriction 16, while the drain port 14 is connected to a tank 24 by a line 22. It is connected. Therefore, from tank 24 to pump 2
A part of the hydraulic oil pumped up by 6 is transferred to pipe 1.
8 to the pressure port 12, and is returned to the tank 24 from the drain port 14 via the conduit 22.

The flow path from the pressure port 12 to the drain port 14 is constricted by a spool 28 serving as a hydraulic control member. The spool 28 is fitted into a spool hole formed in the housing 10 substantially oil-tightly and slidably in the axial direction, and is provided with a land 30 at one end.
Land 30 connects pressure port 12 and drain port 14
However, this land 30 is formed with a notch 32 as shown enlarged in FIGS.
The hydraulic oil guided by the spool 28 is spouted from the annular groove 34 of the spool 28 through the notch 32 into the low pressure chamber 36. Moreover, as is clear from FIG. 2, the notch 32 is formed to become deeper toward the end of the land 30, so that the spool 28
As it moves to the right in the figure, the flow path area in the notch 32 decreases, and the throttling effect on the hydraulic oil flowing from the pressure port 12 to the drain port 14 increases.

An armature tube 38 is fixed to the end of the housing 10 on the low pressure chamber 36 side by screwing, and an armature 40 is disposed within the armature tube 38 so as to be movable in the axial direction. A working protrusion 42 protruding from one end surface of the armature 40 is adapted to come into contact with one end of the spool 28. Further, a solenoid coil 44 is fixed to the outside of the armature tube 38, and this solenoid coil 44 is connected to an AC power source 46 whose voltage is variable. Therefore, when the solenoid coil 44 is supplied with current, the armature 40
4 and applies a force in the positive direction, that is, to the right in FIG. 1, to the spool 28 via the working projection 42. This force in the positive direction increases or decreases as the voltage applied to the solenoid coil 44 by the AC power source 46 increases or decreases. In this embodiment, the solenoid assembly configured as described above is used as a hydraulic control member. It functions as an actuator for driving the spool 28 in the forward direction.

A force in the opposite direction, ie, to the left, is also applied to the spool 28 by the feedback mechanism 50, and at a position where this force and the force in the positive direction by the armature 40 are balanced, the spool 28
has been stopped. The feedback mechanism 50 includes a driving piston 52 and a driven piston 54.
It is equipped with The driving piston 52 consists of a piston main body 56 that is fluid-tightly and slidably fitted into the housing 10 and a plunger 58 fixed thereto, and has a first chamber 6 on opposite pressure receiving surfaces.
0 oil pressure and the second chamber 62 oil pressure. The first room 60 has a feedback passage 6.
3 leads to the hydraulic pressure of the pressure port 12. Further, 64 is a low pressure chamber, which is always communicated with the tank 24 via a drain port 66 and a conduit 68. On the other hand, the driven piston 54 is provided at a position concentrically facing the driving piston 52, and is fixed to one end of the spool 28.
The hydraulic pressure of the third chamber 70 and the fourth chamber 72 are received by pressure receiving surfaces facing oppositely to each other. The third chamber 70 is formed to be continuous with the second chamber 62, and the fourth chamber 72 is a communication passage 74 with a throttle effect formed between the outer peripheral surface of the driven piston 54 and the housing 10. communicated by. The fourth chamber 72 is communicated with the low pressure chamber 36 through a communication passage 76.

A spring 78 is provided between the driving piston 52 and the housing 10, and urges the driving piston 52 toward the retreating side, that is, toward the first chamber 60.
Further, a spring 80 as an elastic member is provided between the driving piston 52 and the driven piston 54. Note that the spring 78 is provided to share a portion of the operating force of the driving piston 52, since a large solenoid assembly would be required if the spring 80 were to receive all of the operating force of the driving piston 52. It is something that exists. In this embodiment, spring 78 is better than spring 8.
Although the spring force is greater than 0, the spring 78 may be omitted if the hydraulic pressure acting on the driving piston 52 is low.

When a constant voltage is applied by the AC power supply 46 to the solenoid coil 44 of the hydraulic control valve configured as described above, and a constant hydraulic pressure is introduced from the pump circuit 20 to the pressure port 12, the spool 28 is stable in the position shown in FIG. That is, the armature 40 applies a positive force to the spool 28 based on the attraction force of the solenoid coil 44, and the spring 80 applies a positive force to the spool 28.
The force applied in the opposite direction is balanced.

As the voltage of the AC power supply 46 is gradually increased from this state, the positive force applied by the armature 40 to the spool 28 increases, causing the spool 28 to move to the right against the elastic force of the spring 80. As a result, the flow path area in the notch 32 is reduced and the throttling effect is enhanced, so that the oil pressure in the pressure port 12 increases and is transmitted to the plunger 58 of the driving piston 52 through the feedback passage 63. As a result, the driving piston 52 is moved by the spring 7.
It moves forward against the elastic force of springs 8 and 80, and
0 is compressed and the force in the opposite direction on spool 28 increases. That is, as the pressure in the pressure port 12 increases, the driving piston 58 moves forward;
This forward movement increases the elastic force of the spring 80, and as a result, the amount of pressure increase in the pressure port 12 and the amount of increase in the force in the opposite direction applied to the spool 28 are proportional. Then, the spool 28 stops when this force in the opposite direction and the force in the forward direction by the armature 40 described above are balanced, so the pressure at the pressure port 12 is equal to the suction force of the armature 40, that is, the voltage of the AC power source 46. The pressure can be changed arbitrarily by changing the pressure, and the hydraulic pressure of this pressure port 12 can be taken out and used for various purposes.

The above is the operation when the voltage of the AC power supply 46 is gradually increased, and when the voltage is suddenly increased, the operation is as follows. If the voltage is suddenly increased, the armature 40 will cause the spool 2 to
The positive force applied to 8 also increases rapidly,
As a result, the oil pressure in the pressure port 12 is rapidly increased. This rise is then transmitted to the first chamber 60 through the feedback passage 63, causing the driving piston 52 to move forward at high speed. When the driving piston 52 moves forward, the volume of the second chamber 62 decreases, and the hydraulic oil there is supplied to the third chamber 70 and further pushed out to the fourth chamber 72 via the communication passage 74. The passage 74 is narrowed to provide a throttling effect, so that the second chamber 62 and the third chamber 7
Oil pressure is generated at 0, and the driven piston 54 receives a leftward force due to this oil pressure. That is, when the voltage of the AC power source 46 is suddenly increased, not only the elastic force of the spring 80 but also the force based on the oil pressure is applied to the spool 28 via the driven piston 54 as a feedback force. The force based on the hydraulic pressure increases as the forward speed of the driving piston 52 increases, that is, as the hydraulic pressure at the pressure port 12 increases rapidly, it counteracts the force in the positive direction of the armature 40, and the spool 28 suddenly moves in the positive direction. This prevents them from moving to.

Examples of experimental results conducted to confirm this effect are shown in FIGS. 4 and 5. The graph in FIG. 4 shows the pressure when voltage is applied to the solenoid coil 44 for a certain short period of time in a state where the passage area of the communication passage 74 is sufficiently large so that no feedback force based on oil pressure is obtained. This shows a change in the oil pressure at port 12, and a clear overshoot has occurred. On the other hand, FIG. 5 shows the result when the flow area of the communication passage 74 is sufficiently reduced to give a throttling effect, and it is clear that according to the present invention, the occurrence of overshoot can be prevented. It is clearly shown.

FIG. 6 shows another embodiment of the invention. In this embodiment, the present invention is applied to a pilot pressure control valve that controls the pilot pressure of a seating valve type main hydraulic control valve. The main hydraulic control valve 82 includes a valve seat 84 formed in the housing 10 and a poppet valve 86, and one end of a spring 88 that biases the poppet valve 86 in the closing direction is held by a spring receiver 92 fixed to a piston 90. As the pilot pressure acting on the piston 90 increases, the piston 90 moves forward while compressing the spring 94, thereby compressing the spring 88 and increasing the elastic force acting on the poppet valve 86. The hydraulic pressure of the pressure port 96 is configured to be increased. A pilot pressure control valve having the spool 28 as its main body is provided in the middle of the drain passage of the main hydraulic control valve 82, so that the controlled hydraulic pressure is applied to the piston 90 as pilot pressure. -ing

Since the configuration of this pilot pressure control valve is the same as that of the hydraulic control valve of the previous embodiment, corresponding parts are given the same reference numerals and detailed explanation is omitted. A piston 90 for controlling the valve opening pressure of the feedback mechanism 5
It is used as the driving piston of 0. That is, the arm 100 is extended from the piston 90, and the spring 80 is disposed between the arm 100 and the driven piston 54.

Therefore, the oil chamber formed at the rear of the piston 90 functions as the first chamber 60, and the oil chamber formed at the front functions as the second chamber 62.

Another embodiment of the invention is shown in FIG. In this embodiment, the present invention is applied to a pilot pressure control valve for controlling the pilot pressure of a spool type directional flow rate control valve. In the figure, 102 is a housing, and P port 10 is connected to the pump.
4, an A port 106 and a B port 108 connected to an actuator such as a hydraulic cylinder, and a T port 110 connected to a tank. A spool 112 is provided within the housing 102 so as to be slidable in the axial direction.
The spool 112 is normally kept in a neutral position by a pair of springs 114 and spring receivers 116 provided on both sides, blocking communication with all ports, but if any one of the pressure-receiving surfaces at both ends When the pilot pressure acting on the port is increased, it is moved to the left or right against the elastic force of the spring 114, causing the P port 104 to communicate with either the A port 106 or the B port 108, and the T port 110 is communicated with the remaining port to control the direction, and the flow rate between these ports is also controlled depending on the distance traveled from the neutral position.

The pilot pressure acting on both ends of the spool 112 is controlled by two sets of pilot pressure control valves, which are constructed symmetrically to each other, and the construction of one set is shown in FIG. Since it is almost the same as the example shown, only one set has the first
The same reference numerals as those in the illustrated embodiment are used, and detailed explanation will be omitted. Furthermore, as is clear from the figure,
In this embodiment, the spool 112 functions as a driving piston, and when the left pilot pressure control valve is activated, the oil chamber formed on the right side of the spool 112 functions as the first chamber 60.

Another embodiment is shown in FIG. In this embodiment, a piston 118 is moved by hydraulic pressure supplied to an oil chamber 120 against the elastic force of a spring 122, and a driven member 1 is engaged with the piston 118.
24 (for example, a control pin for controlling the inclination angle of the swash plate of a swash plate type variable displacement pump). It is something. In this embodiment, the piston 118 of the actuator 126 is used as a driving piston, and the oil chamber 120 functions as the first chamber. Since this embodiment is the same as the embodiment shown in FIG. 1, corresponding parts are the same. The detailed explanation will be omitted. In this embodiment, a bypass passage 128 is formed from the third chamber 70 to the communication passage 76, and a variable throttle 13 is provided in the middle of the bypass passage 128.
0 is provided so that the throttling effect of the communication path 74 can be adjusted.

In this embodiment, the force acting on the piston 118 is not only the force based on the oil pressure led to the oil chamber 120 and the elastic force of the springs 80 and 122, but also the reaction force from the driven member 124, so that the force acting on the piston 118 is The elastic force and the oil pressure in the oil chamber 120 do not necessarily have a one-to-one correspondence. That is, if the reaction force from the driven member 124 increases while the device of this embodiment is stable, the piston 118 will move toward the oil chamber 120, but as a result, the elastic force of the spring 80 will decrease. The spool 28 moves in the forward direction and the notch 32
The oil pressure in the pressure port 12 increases in order to enhance the throttling effect, and as a result, the oil pressure in the oil chamber 120 increases to a value that can counteract the reaction force from the driven member 124. As a result, the oil pressure in the oil chamber 120 generates a force in the opposite direction on the spring 80 that is the same magnitude as the force in the positive direction applied from the armature 40 to the spool 28, regardless of the reaction force from the driven member 124. It is controlled as follows.

Yet another embodiment of the invention is shown in FIG. In this embodiment, an oil chamber 120 is provided in the piston 118.
Another oil chamber 1 that applies hydraulic pressure in the opposite direction to the hydraulic pressure of
32 are provided. And this oil chamber 132
The hydraulic pressure of the pump circuit 20 is guided to the pump circuit 20 by a passage 134. The pressure receiving area of the piston 118 on the oil chamber 132 side is approximately one half of the pressure receiving area on the oil chamber 120 side.
When approximately half the hydraulic pressure of the pump circuit 20 is applied to the oil chamber 120, the piston 118
The forces acting on it are balanced. This oil chamber 132 includes the driving piston 52, the piston 90, the spool 112, etc., as well as the springs 78, 94, 114, 122, etc.
It applies a force in the opposite direction to the force applied to the piston 118, etc. by the hydraulic pressure in the first chamber 60, oil chamber 120, etc. In this sense, the oil chamber 132, together with the above-mentioned springs, serves as a counterforce applying means. It should be referred to collectively.

Yet another embodiment of the invention is shown in FIG.

This embodiment differs from the embodiment of FIG. 1 in that feedback passage 63 is adapted to be placed in alternative communication with pressure port 12 and drain port 14 by the action of spool 28. That is, the port that was the pressure port 12 in the embodiment of FIG. 1 is the pressure outlet port 140 in this embodiment, and the pressure port 1 is
2 is provided separately. Spool 28
In addition to the land 30 and notch 32, a land 142 and a notch 144 are provided,
Feedback passage 63 and pressure outlet port 140 are communicated with drain port 14 and pressure port 12 through cutouts 32 and 144, respectively.

The functions and effects of this embodiment are almost the same as those of the embodiment shown in FIG. 1, so the explanation will be omitted.
This has the advantage that only a small amount of hydraulic oil is required to be refluxed. In addition, in this embodiment, pressure port 1
Of the oil passage from 2 to the drain port 14, a short portion that is constantly in communication with the pressure extraction port 140 is an upstream portion whose hydraulic pressure is controlled by the spool 28, which is a hydraulic control member.

Although several embodiments of the present invention have been described above,
The present invention can further be implemented in various embodiments. For example, in all of the above embodiments, the spool, which is a hydraulic control member, is actuated by an AC solenoid assembly in which the armature is attracted by an AC solenoid.
In this case, the suction force of the solenoid is less likely to change depending on the temperature, and the hysteresis when the oil pressure rises and falls is small, which has the advantage of providing a hydraulic control valve with excellent stability and precision. However, it is also possible to operate the armature by a DC solenoid assembly in which the armature is attracted by a DC solenoid, or by other actuators such as a manual operating mechanism. The hydraulic control member is also not limited to the spool, but is a member that can control the hydraulic pressure by balancing the driving force in the forward direction applied by the actuator with the feedback force in the opposite direction applied by the feedback mechanism. It's good to have it. Furthermore, the communication passage having a throttling effect connecting the third chamber and the fourth chamber is not necessarily limited to the annular gap formed between the outer circumferential surface of the driven piston and the housing; The driven piston may be fitted in a fluid-tight manner into the housing, forming a communication passage with a throttling effect in the driven piston, or, as in the embodiment shown in FIG. A diaphragm may also be provided. Further, in each of the above embodiments, the fluid whose pressure is controlled is hydraulic oil, but it may be any other liquid such as a suspension.

Although not illustrated in detail, it is of course possible to carry out the present invention in various modifications and improvements based on the expertise of those skilled in the art without departing from the spirit of the invention.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of a hydraulic control valve including a feedback mechanism, which is an embodiment of the present invention. FIG. 2 is a partially cutaway front view showing only the spool of the hydraulic control valve, and FIG. 3 is a plan view showing a portion of the spool. 4 and 5 are graphs showing an example of an experiment conducted to confirm the effects of the present invention. FIG. 3 is a diagram showing hydraulic control characteristics. FIG. 6 is a front view showing an embodiment in which the present invention is applied to a pilot pressure control valve that controls the pilot pressure of a main hydraulic control valve. FIG. 7 is a front sectional view showing an embodiment in which the present invention is applied to a pilot pressure control valve for controlling the pilot pressure of a spool type directional flow rate control valve. FIGS. 8 and 9 are front sectional views showing respective embodiments in which the present invention is applied to a hydraulic control valve that controls the working oil pressure of an actuator. FIG. 10 is a front sectional view showing another hydraulic pressure control valve equipped with a feedback mechanism, which is an embodiment of the present invention. 10: Housing, 12: Pressure port, 14:
Drain port, 28,112: Spool, 30,
142: Land, 32, 144: Notch, 40:
Armature, 44: Solenoid coil, 46:
AC power supply, 50: feedback mechanism, 52: driving piston, 54: driven piston, 60: first chamber, 62: second chamber, 63: feedback passage,
70: Third chamber, 72: Fourth chamber, 74, 76: Communication path, 78, 80, 94, 114, 122: Spring, 82: Main hydraulic control valve, 90, 118: Piston, 120, 132: Oil chamber , 126: Actuator, 140: Pressure extraction port.

Claims (1)

[Claims] 1. Provided in the middle of a liquid passage, when moved in the forward direction by an actuator, increases the liquid pressure in the upstream side of the liquid passage, and when moved in the opposite direction, increases the liquid pressure In the hydraulic control valve equipped with a hydraulic pressure control member that lowers the hydraulic pressure, a force of a magnitude related to the hydraulic pressure in the upstream portion of the liquid passage is applied to the hydraulic pressure control member to move the hydraulic pressure control member in the opposite direction. It is a mechanism that provides feedback in the direction of movement, and includes a driving piston that receives hydraulic pressure in a first chamber and hydraulic pressure in a second chamber, respectively, on pressure receiving surfaces facing oppositely to each other, and a driving piston that receives hydraulic pressure in a first chamber and hydraulic pressure in a second chamber, respectively, and connects the hydraulic pressure control member directly or with another member. a driven piston that is indirectly connected through the piston and receives the hydraulic pressure of the third chamber and the hydraulic pressure of the fourth chamber on pressure receiving surfaces facing oppositely to each other; the second chamber communicates with the third chamber, the third chamber communicates with the fourth chamber through a communication passage having a throttling effect, and the fourth chamber is connected to the downstream side of the liquid passage. means for communicating with the hydraulic pressure control member, the means being provided between the driving piston and the hydraulic pressure control member, and controlling the hydraulic pressure with an elastic force that changes in response to a change in the relative position between the driving piston and the hydraulic pressure control member. A feedback mechanism for a hydraulic control valve, comprising: an elastic member that biases the control member in the opposite direction.