JP2693792B2 - Flow control valve device - Google Patents

Description

The present invention relates to a flow control valve device, and more particularly to a flow control having a pressure compensation function suitable for controlling the drive of a hydraulic actuator in a hydraulic machine such as a hydraulic shovel. Regarding the valve device.

<Prior Art> A conventional flow control valve device with a pressure compensation function is a PCT,
pub. No. WO83 / 01095, ie, as shown in FIG. 7, between a housing 3 with a main fluid passage having an inlet port 1 and an outlet port 2 and between the inlet port 1 and the outlet port 2. Is formed of a main valve 4 arranged to communicate with and shuts off the inflow port 1 and the outflow port 2, and a valve body of the housing 3 and the main valve 4, and applies a fluid pressure to the main valve body in a valve closing direction. A pilot valve for operating the main valve 4 by selectively opening and closing the pressure chamber 5, the auxiliary passage 6 for connecting the back pressure chamber 5 and the outflow port 2, and changing the fluid pressure in the back pressure chamber 5 7 and 7. The main valve 4 is configured as a seat valve, and a plurality of slits 9 forming a variable throttle are formed between the main valve valve body and a cylindrical sleeve 8 fixed to the housing 3, and the back pressure chamber 5 is The slot 9 communicates with the inflow port 1. Auxiliary passage 6
Is formed in the housing 10 adjacent to the housing 3, and the valve piston 11 of the pressure compensating valve is arranged between the pilot valve 7 and the back pressure chamber 5 of the auxiliary passage 6. This valve piston
The pressure of the inflow port 1 is guided to one end of the valve 11 via the first communication passage 12, and the pressure of the back pressure chamber 5 is guided to the other end of the valve piston 11 via the second communication passage 13. There is.

When the pilot lever 7 of the pilot valve 7 is operated to open the pilot valve 7, the fluid in the inflow port 1 flows to the outflow port 2 through the slit 9 of the variable throttle, the back pressure chamber 5, and the auxiliary passage 6, and the pilot flow. Is formed. At this time, since the fluid flowing from the inflow port 1 to the back pressure chamber 5 is throttled by the variable throttle, a pressure difference is generated between the inflow port 1 and the back pressure chamber 5, and the fluid pressure in the back pressure chamber 5 is It is lower than the fluid pressure in the inflow port 1. This opens the main valve body,
The fluid in the inflow port 1 flows out to the outflow port 2 through the main valve 4. At this time, since the pilot flow rate is determined by the set opening degree of the pilot valve 7 and the fluid pressure in the back pressure chamber 5 is determined by the flow rate flowing through the slit 9, that is, the pilot flow rate, the opening degree of the main valve body is eventually determined by the pilot valve. The flow rate proportional to the operation amount of the pilot valve 7 can be obtained in the main fluid passage.

In such a state, for example, when the fluid pressure in the inflow port 1 rises and the differential pressure between the inflow port 1 and the outflow port 2 increases, the flow rate through the main valve 4 tends to increase,
At the same time, the pilot flow rate also tries to increase, and the differential pressure between the pressure in the inlet side chamber 15 and the pressure in the outlet side chamber 16 of the pilot valve 7 increases. At both ends of the valve piston 11 of the pressure compensation valve, an inflow port 1 is provided via a first communication passage 12 and a second communication passage 13.
Since the differential pressure between the fluid pressure of the above and the pressure of the back pressure chamber 5 is introduced, the valve piston 11 is displaced according to the increase of the differential pressure, and throttles the pilot flow rate. As a result, the flow rate of the pilot is reduced, the throttling action of the slit 9 is reduced, the pressure in the back pressure chamber 5 is increased, and the opening degree of the main valve 4 is reduced. As a result, the flow rate flowing through the main fluid passage is maintained in a predetermined relationship, for example, constant, with respect to the pressure increase in the inflow port 1, and pressure compensation is performed.

<Problems to be Solved by the Invention> However, in this conventional flow control valve device, a highly accurate pressure compensation valve including the valve piston 11 is required, and a variable throttle is provided in the main valve body. A plurality of slits 9 having high dimensional accuracy are required, and the auxiliary passage 6 and the first communication passage 12 and the second passage are provided in the housings 3 and 10.
Since a fluid passage having a complicated path including the communication passage 13 of is required, there is a problem that the structure is complicated, manufacturing and assembling man-hours are increased, and the manufacturing cost is increased, and the pressure compensation increases the pilot valve flow rate. Since it is performed via a pressure compensating valve that is controlled, there is a problem that the followability to pressure changes is not sufficient.

An object of the present invention is to provide a flow control valve device having a pressure compensation function, which has a relatively simple structure, can reduce the number of manufacturing and assembling steps, and can reduce the manufacturing cost.

Another object of the present invention is to provide a flow rate control valve device having a pressure compensating function that is excellent in followability to pressure changes.

<Means for Solving the Problems> In order to achieve this object, the present invention provides a housing including a main fluid passage having an inflow port and an outflow port,
The main valve is disposed between the inflow port and the outflow port and connects and disconnects the inflow port and the outflow port, and is formed by the inner wall of the housing and the valve body back portion of the main valve, and the inflow port is connected to the inflow port through the throttle. A back pressure chamber that communicates,
An auxiliary passage that connects the back pressure chamber and the outflow port,
In a flow control valve device comprising a pilot valve for controlling opening / closing of the auxiliary passage and changing the fluid pressure of the back pressure chamber to operate the main valve, the flow control valve device is disposed in the main fluid passage, In the differential pressure generating means for generating a differential pressure according to the flow rate, a displacement body that is movable in the fluid flow direction of the main fluid passage, and a biasing body for the displacement body in a direction opposite to the fluid flow direction. Differential pressure generating means for defining a flow path between the displacement body and a wall surface of the fluid passage, the flow passage having an opening area increasing in accordance with an increase in the moving stroke of the displacement body, and the differential pressure generation means. With a control means for controlling the operating force of the pilot valve according to the differential pressure generated by the means, a displacement detection means for detecting the displacement of the displacement body, and a detection value output from the displacement detection means. Compensate the operating force of the pilot valve Are the configuration in which the correction means.

<Operation> In the present invention configured as described above, when an operation force corresponding to the command operation amount is applied to the pilot valve, the pilot valve is opened, and the fluid in the inflow port is throttled, the back pressure chamber,
A pilot flow is formed which flows through the auxiliary passage to the outflow port. At this time, since the fluid flowing from the inflow port to the back pressure chamber is throttled by the throttle, a pressure difference occurs between the inflow port and the back pressure chamber, and the fluid pressure in the back pressure chamber becomes the fluid pressure in the inflow port. It decreases in comparison. Due to this pressure drop, the main valve valve body opens, and the fluid in the inflow port flows out to the outflow port through the main valve. At this time, the differential pressure generating means arranged in the main fluid passage detects the flow rate as a differential pressure, and the control means controls the operating force of the pilot valve according to the differential pressure. As a result, the opening of the pilot valve is adjusted, the pressure of the back pressure chamber is changed, the opening of the main valve is adjusted, and a flow rate according to the operating force of the pilot valve can be obtained in the main fluid passage.

In such a state, for example, when the fluid pressure in the inflow port rises and the differential pressure between the inflow port and the outflow port increases, the flow rate through the main valve transiently increases, but the differential pressure generating means The operating force of the pilot valve is controlled according to the increase, and the opening degree of the pilot valve is reduced. Therefore, the pressure in the back pressure chamber increases, the opening degree of the main valve valve element decreases, and the flow rate of the main fluid passage decreases. As a result, the flow rate of the main fluid passage is maintained in a predetermined relationship with the increase in pressure of the inflow port, and the pressure compensation function is fulfilled.

Further, according to the present invention, the displacement of the displacement body is detected by the displacement detecting means, and the displacement of the displacement body corresponding to the operating force applied to the pilot valve is actually operated. If there is a deviation from the displacement of the displacing body, the correction means corrects the operation value to eliminate the above deviation according to the detection value of the detection means. It is possible to realize stabilization of the flow rate flowing through in a shorter time.

<Example> Hereinafter, the flow control valve device of the present invention will be described with reference to the drawings.

In FIG. 1 showing the first embodiment, the flow control valve device is generally designated by the numeral 20. Flow control valve device 20
Is a main fluid passage having an inflow port 21 and an outflow port 22
A main valve 25 is provided which has a housing 24 provided with 23 and which connects and disconnects the inflow port 21 and the outflow port 22 in the housing 24. The main valve 25 includes a valve body 27 housed in a valve chamber 26 formed in the housing 24 so as to be movable in the axial direction,
The valve body 27 is configured as a seat valve including a housing 24 with which the valve body 27 engages and a valve seat 28 that is integral with the valve body 27. Has a back 29. Also within the housing 24, as part of the valve chamber 26,
A back pressure chamber 31 is formed by the inner walls of the housings 24 and 30 and the back portion 29 of the main valve body 27, and the back pressure chamber 31 is provided in the inflow port 21 through the throttle 32 provided in the back portion 29 of the main valve body 27. Communicate with each other. A through hole 33 is formed in the main valve body 27, and a wall portion forming a back pressure chamber 31 of the housing 30 projects toward the main valve body 27, seals in the through hole 33, and relatively slides. It has a fixed guide 34 of the main valve valve body 27 which is made free, and this fixed guide 34 is coaxially provided with a through hole 35 in communication with the through hole 33.
Opening and closing of the through hole 35 is controlled by a pilot valve 36.

The pilot valve 36 is a valve spool 38 slidably disposed in a pilot cylinder chamber 37 formed in the housing 30.
And a poppet portion 39 as a valve body protruding in the direction of the through hole 35.
And a valve seat 40 integral with the housing 24 on which the poppet portion 39 is provided. A first pressure chamber 41 is formed at the upper end of the valve spool 38 in the figure, and a second pressure chamber 42 is formed at the lower end of the valve spool 38 in the figure. The second pressure chamber 42 is formed by a flow path 43 formed in the housing 30. Through the back pressure chamber 31. A return spring 44 for urging the valve spool 38 upward in the drawing is arranged in the second pressure chamber 42, and the return spring 44 is locked by a spring receiver 45 mounted on the valve spool 38. An auxiliary passage that connects the back pressure chamber 31 to the outflow port 22 is formed by the through holes 33 and 35, the second pressure chamber 42, and the flow path 43 described above.

Further, on the outflow port 22 side of the main fluid passage 23, a differential pressure generating means 46 that generates a differential pressure according to the flow rate of the main fluid passage 23 is arranged. The differential pressure generating means 46 has a displacement body 48 composed of a cone, which is movably supported in the fluid flow direction by a guide 47 integral with the housing 24, and a displacement body 48 is provided between the guide 47 and the displacement body 48. A spring 49 for urging in a direction opposite to the fluid flow direction is provided. Displacement body 48 is the main fluid passage
A flow path whose opening area increases in accordance with an increase in the movement stroke of the displacement body 48 is defined between the curved wall surface 50 and 23. The outer diameter of the displacement body 48 is smaller than the inner diameter of the outflow port 22. Here, the wall surface of the main fluid passage 23 has an opening area with the displacement body 48 with respect to the displacement amount x of the displacement body 48. The wall shape is a root function or a function close to the root function. A stopper or nut 52 for restricting the upward movement of the displacement body 48 is fastened to a support rod 51 forming the lower portion of the displacement pair 48 in the figure.

Further, for example, a proportional solenoid valve 53 is provided as a drive means for driving the pilot valve 36, and an output shaft 54 of the proportional solenoid valve 53 is in contact with an upper end surface of the valve spool 38 of the pilot valve 36 in the figure. The output shaft 54 of the proportional solenoid valve 53, the pilot valve 36, the main valve 25, and the differential pressure generating means 46 are arranged coaxially.

Further, as a control means for controlling the operating force of the pilot valve 36 in accordance with the differential pressure generated by the differential pressure generating means 46, it is formed over the two housings 24, 30 and has a passage portion on the downstream side of the displacement body 48. A passage 55 communicating with the above-mentioned first pressure chamber 41.
Is provided.

Further, the detection rod is attached to the lower end of the support rod 51 of the displacement body 48.
56 is connected, and the detection rod 56 is attached to the lower end of the housing 24 and penetrates into an electric displacement detector 58 having a detection coil 57. The detection rod 56 and the displacement detector 58 constitute displacement detection means for detecting the displacement of the displacement body 48.

The displacement detector 58 described above is connected to the comparison calculator 59,
This comparison calculator 59 is a displacement detector 58 via signal lines 60 and 61.
It is also connected to a command device (not shown) and is also connected to the control driver 63 via a signal line 62. The control driver 63 is connected to the proportional solenoid valve 53 via a signal line 64. The above-mentioned comparison calculator 59 is a displacement output corresponding to the signal (detection value) output from the displacement detector 58 via the signal line 60 and the command operation amount for driving the pilot valve 36 output via the signal line 55. The target displacement of the body 48 is compared and the calculation is performed. This comparison calculator 59 is a pilot valve according to the detection value output from the displacement detection means including the displacement detector 58.
It constitutes a correction means for correcting the operating force of 36. Also,
The comparison calculator 59 stores in advance, for example, the relationship shown by the characteristic line 65 in FIG. 3, that is, the desired functional relationship between the operating force Fc, which is the force applied to the pilot valve 36, and the displacement amount x of the displacement body 48. There is.

The inflow port 21 of this flow control valve device 20 is a hydraulic cylinder.
66, the outflow port 22 is connected to a tank 67, and the hydraulic cylinder 66, the tank 67, and the flow control valve device 20 constitute a meter-out control system, for example.

The operation of the embodiment thus configured is as follows.

When the proportional solenoid valve 53 is not driven and the pilot valve 36 is not operating, the poppet portion 39 of the pilot valve 36 is urged upward in the figure by the force of the spring 44, and the poppet portion 39 is seated in the valve seat.
Stick with 40. The pressure fluid in the inflow port 21 is guided to the back pressure chamber 31 via the throttle 32 of the main valve body 27. Therefore, the main valve body 27 is pressed downward in the figure due to the area difference between the end faces 68 and 69, abuts against the valve seat 28, and the inflow port 21
To block the flow of fluid from the outlet port 22 to the outlet port 22.

From this state, when a command device (not shown) is driven and its electric signal is given to the comparison calculator 59, the control driver 63 operates and the output shaft 54 of the proportional solenoid valve 53 moves downward in the drawing, and the pilot valve 36. Operating force Fc according to the operation command amount
give. As a result, the poppet portion 39 of the pilot valve 36 moves downward in the figure, and the valve seat 40 is opened. At this time, the fluid in the inflow port 21 is the throttle 32, the back pressure chamber 31, the flow path 43, the second
It flows into the through holes 35, 33 through the pressure chamber 42. Then, due to the throttle 32, the fluid pressure in the back pressure chamber 31 becomes lower than the fluid pressure in the inflow port 21. Here, when the force acting on the end face 69 overcomes the force acting on the end face 68 of the main valve body 27, the main valve body 27 moves upward in the figure, and the fluid in the inflow port 21 flows out to the outflow port 22. To do. Then, the fluid flowing into the outflow port 22 pushes the displacement body 48 of the differential pressure generating means 46 downward in the drawing. The fluid pressure on the downstream side of the displacement body 48 is introduced into the first pressure chamber 41 via the passage 55. On the other hand, the pressure on the upstream side of the displacement body 48 is guided to the second pressure chamber 42 via the through holes 33, 35.
Therefore, the differential pressure generated between the upstream side and the downstream side of the displacement body 48 is applied to the valve spool 38 of the pilot valve 36 as a force. Assuming that the cross-sectional area of the pilot cylinder chamber 37 is a and the above-mentioned pressure difference is ΔP, Fc = Fc = when the force of the spring 44 is set to a negligible amount in the state where the force of the valve spool 38 is balanced. a · ΔP. That is, a differential pressure ΔP corresponding to the operating force Fc of the pilot valve 36 is generated, and a flow rate corresponding to this differential pressure ΔP is obtained.
In this case, in a steady state, the opening degree of the poppet portion 39 of the pilot valve 36 is determined by the area ratio of the end face 68 and the end face 69 of the main valve body 27, the strength of the throttle 32, and the inclination angle of the poppet portion 39. It The degree of opening of the main valve body 27 is determined by the degree of opening between the displacement body 48 and the wall surface 50 and the pressure difference between the inflow port 21 and the outflow port 22.

Then, if the pressure of the inflow port 21 rises from such a state and the flow rate of the inflow port 21 tries to increase, the displacement body 48 is pushed downward in the figure against the spring 49, and the through hole 33 and the outflow port 22. The fluid pressure difference in the inside increases, whereby the valve spool 38 of the pilot valve 36 moves upward in the drawing, and the opening area of the poppet portion 39 is reduced. As a result, the pressure in the back pressure chamber 31 rises, the main valve body 27 moves downward, the valve opening is reduced, and the increase in the flow rate is suppressed. In this way, a desired flow rate according to the operating force Fc is obtained regardless of the fluid pressure difference between the inflow port 21 and the outflow port 22.

This can be expressed by the following formula. First, the opening area A between the displacement body 48 and the wall surface 50 is determined by the shape setting of the wall surface 50 as described above. It is represented by If the flow rate passing through this opening area A is Q, (C is a constant determined by the fluid density and shape). Further, if the spring constant of the spring 49 is k, then ΔP
Is represented by ΔP = kx / Ap (Ap is the pressure receiving area of the displacement body 48). This allows From the above Fc = a · ΔP, Becomes

From the above equation, it is found that the flow rate Q is linearly proportional to the operating force Fc, and therefore a flow rate characteristic linearly proportional to the operating force Fc of the pilot valve 36 can be obtained. Similarly, from the above equation, it is found that the flow rate Q is not affected by the differential pressure ΔP, and the flow rate Q can be kept constant even if the differential pressure ΔP increases, and the pressure compensation function is fulfilled.

In addition, when the influence of flow force is taken into consideration in the above equation, it becomes an equation in which the relational expression f (ΔP) of ΔP is added,
By changing the shape of the main valve 25 for the seat and using the flow force, the flow rate Q can be made to slightly depend on the differential pressure ΔP, whereby the flow rate having a predetermined relationship with the increase of the differential pressure ΔP can be obtained. It is possible to obtain the pressure compensation function to be ensured, and at the same time, to adapt it to the flow rate characteristic required by a specific hydraulic cylinder 66.

The above relationships are shown in FIGS. 2 (a) to 2 (d). That is, first, as shown in FIG. 2 (a), the operating force Fc generated in the proportional solenoid valve 53 in accordance with the input current value i corresponding to the command operation amount of the command device (not shown) has a substantially proportional relationship. As shown in Fig. 2 (b), the operating force Fc and the displacement body
The displacement amount x of 48 is in a proportional relationship, and the output flow rate Q from the main valve 25 and the displacement amount x of the displacement body 48 are in a proportional relationship as shown in FIG. 2 (c). Figure (d)
As shown in, the output flow rate Q and the operating force Fc have a proportional relationship.

However, as described above, the pilot valve 36 by detecting the differential pressure between the pressure on the upper fluid side and the pressure on the downstream side of the displacement body 48.
However, due to the swinging of the displacement body 48 caused by the change in the differential pressure, it takes a little time for the stabilization as shown by the characteristic line 70 in FIG.

This embodiment also takes the above points into consideration. That is, during the control of the pilot valve 36 by the above-mentioned differential pressure, the displacement amount x of the displacement body 48 is detected by the displacement detector 58 via the detection rod 56, and the detected value is input to the comparison calculator 59. Then, the comparison calculator 59 compares the target displacement of the displacement body 48 based on the command operation amount with the above-mentioned detected value. In this case, as described above, the relation between the desired operating force Fc shown by the characteristic line 65 in FIG. 3 and the displacement amount x of the displacement body 48 is stored in advance in the comparison calculator 59, but it is temporarily set as a target. Assuming that the command operation amount corresponding to the operation force F1 is given to the comparison calculator 59, the displacement amount x of the displacement body 48 from the characteristic line 65.
Is calculated as x2, and this x2 is the target displacement. However, the actual detection value detected by the displacement detector 58 is x1.
Then, a deviation of Δx = x2-x1 occurs between the target displacement x2 and the detected value x1. On the characteristic line 71 including the detected value x1, if the operating force that can give the displacement amount x2 is F2, correction that adds the correction amount ΔF obtained by ΔF = F2-F1 to the target operating force F1 can be performed. Thus, the desired target displacement x2 can be obtained.

In this way, the comparison calculator 59 calculates the target displacement x2 and the detected value x1.
Operational force F1 targeting the correction amount ΔF according to the deviation Δx
And the corresponding signal is output to the control driver 63 via the signal line 62. The proportional solenoid valve 53 drives the pilot valve 36 with an operating force of F1 + ΔF by the signal output from the control driver 63 via the signal line 64. As a result, as shown by the characteristic line 72 in FIG. 4, the time required for stabilization can be significantly shortened as compared with the case of the characteristic line 70.

In the first embodiment configured as described above, a flow rate characteristic that is substantially linearly proportional to the command operation amount and a pressure compensation function that secures a substantially constant flow rate with respect to an increase in differential pressure are achieved. You can Then, the flow rate control device 20 does not provide the pressure compensating valve and the slit of the variable throttle, and the displacement body 4
8. It has a relatively simple structure in which only the spring 49 is provided, and the passage structure is simplified by providing the through hole 33 as the through hole of the main valve body 27. Therefore, the number of manufacturing steps is small and the manufacturing cost can be reduced. Further, instead of using the pressure compensating valve for controlling the pilot flow rate, the differential pressure generating means 46 arranged in the main fluid passage 23 directly detects an increase in the flow rate, and further the displacement body 48 detected by the differential pressure detector 58 is detected. Since the operating force Fc is corrected according to the detected value of, the flow rate can be stabilized in a short time,
This makes it possible to perform differential pressure compensation with excellent followability.

FIG. 5 is a sectional view showing a second embodiment of the present invention.
In the second embodiment, the pilot valve 36 is provided integrally with the plunger 73 of the proportional solenoid valve 53, and the displacement body 48 of the differential pressure generating means 46 is dimensioned so as to also serve as a check valve. The control means for controlling the operating force of the pilot valve 36 is constituted by spring means for urging the displacement body 48 and the valve body 74 of the pilot valve 36 in the proximity direction, for example, a tension spring 75. This tension spring 75 is inserted into the through hole 35 formed in the main valve body 27, and the upper end in the figure is the valve body of the pilot valve 36.
74 is attached to the lower end of the figure and is a displacement body of the differential pressure generating means 46.
The pilot valve 36, the main valve 25 including the tension spring 75, and the displacement body 48 are coaxially arranged. The portion near the upper end of the through hole 35 of the main valve body 27 in the figure is a pilot valve.
36 movable valve seats 76 are formed. In addition, an auxiliary passage that connects the back pressure chamber 31 and the outflow port 22 is formed by the through hole 35 formed in the main valve body 27. Other configurations, i.e.
The configuration including the displacement detector 58, the comparison calculator 59 constituting the correction means, the control driver 63, etc. is, for example, equivalent to that of the first embodiment shown in FIG.

Since the displacement body 48 also serves as a check valve in the second embodiment, for example, the inflow port 21 is connected to the hydraulic pump 77 and the outflow port 22 is connected to the head side of the hydraulic cylinder 66 to form a meter-in circuit. can do.

The second embodiment configured in this way is provided with the displacement body 48 and the wall surface.
The opening area A with 50 depends on the shape of the wall surface 50, as described above. It is represented by The flow rate Q passing through the opening area A is, as described above, (C is a constant determined by the fluid density and shape). Here, the sum of the spring constants of the spring 49 and the tension spring 75 is k
Then, the differential pressure ΔP between the pressure on the upstream side and the pressure on the downstream side of the displacement body 48 is represented by ΔP = kx / Ap (pressure receiving area of the Ap displacement body 48).

This allows And, from the operating force Fc = k · x, Becomes

As described above, also in the second embodiment, the flow rate Q is linearly proportional to the operating force Fc and linearly proportional to the operating force Fc of the pilot valve 36 as in the first embodiment. Flow rate characteristics are obtained, and the flow rate Q is not affected by the differential pressure ΔP.
Can be kept constant, and the pressure compensation function is fulfilled.

Then, as in the first embodiment, the comparison calculator 59 corrects the operating force according to the detection value detected by the differential pressure detector 58, so that the flow rate can be changed in a short time as in the first embodiment. Stabilization can be realized and excellent followability can be obtained.

FIG. 6 is a sectional view showing a third embodiment of the present invention.
In the third embodiment, the drive means for driving the pilot valve 36 comprises an oil pressure supply device for supplying oil pressure. That is, a piston portion 78 is provided in the pilot valve 36, and pressure chambers 79,
80 is provided, a spring 81 for urging the pilot valve 36 in the direction of the main valve body 27 is provided, and passages 82, 83 communicating with the pressure chambers 79, 80 are provided. The passage 83 is in communication with a proportional solenoid valve 84, and the passage 82 is a tank.
67, and connect the control driver 63 to the signal line.
It is connected to the drive part of the proportional electromagnetic pressure reducing valve 84 via 64, and the proportional electromagnetic pressure reducing valve 84 is connected to the hydraulic pressure source 85.

The hydraulic power source 85, the proportional electromagnetic pressure reducing valve 84, the passages 82 and 83,
Pressure chambers 79, 80, piston part 78 of the pilot valve 36, spring 81
The hydraulic pressure supply device is configured by the above. The other structure is the same as that of the fourth embodiment shown in FIG.

In the third embodiment, the proportional electromagnetic pressure reducing valve 84 is driven via the drive of the control driver 63 according to the command operation amount given to the comparison calculator 59, and the pressure oil supplied from the hydraulic power source 85 is supplied. Is guided to the pressure chamber 80 via the passage 83, whereby the pilot valve 36 moves upward in the figure against the force of the spring 81. As shown in this third embodiment, the pilot valve 36 can be driven by hydraulic pressure.

Other operations in the third embodiment configured in this way,
The effect is the same as that of the second embodiment shown in FIG.

<Effects of the Invention> In the flow rate control valve device of the present invention configured as described above, since the differential pressure generating means and the control means can have a relatively simple structure, the overall structure is simplified. ,
The number of manufacturing and assembling steps is small. Further, instead of using the pressure compensating valve for controlling the flow rate of the pilot valve, the increase in the flow rate is directly detected by the differential pressure generating means including the displacement body arranged in the main fluid passage, and at the same time, the correction means detects the displacement detector. Since the operating force of the pilot valve is corrected according to the detected value, it is possible to perform differential pressure compensation with excellent followability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a flow control valve device of the present invention, and FIGS. 2 (a), (b), (c) and (d) are respectively the first embodiment shown in FIG. FIG. 3 is an explanatory diagram showing the basic characteristics obtained in the embodiment, FIG. 3 is a diagram for explaining the correction processing of the comparison operation unit provided in the first embodiment, and FIG. 4 is a follow-up obtained in the first embodiment. And FIG. 5 is a second diagram of the present invention.
FIG. 6 is a sectional view showing a third embodiment of the present invention, and FIG. 7 is a sectional view showing a conventional flow control valve device. 20 ... Flow control valve device, 21 ... Inflow port, 22 ... Outflow port, 23 ... Main fluid passage, 24, 30 ... Housing, 25
...... Main valve, 26 …… Valve chamber, 27 …… Valve element, 28 …… Valve seat, 29…
… Back, 31 …… Back pressure chamber, 32 …… Throttle, 33,35 …… Through hole, 34 …… Fixed guide, 36 …… Pilot valve, 37 …… Pilot cylinder chamber, 38 …… Valve spool, 39… … Poppet part, 40 …… Valve seat, 41 …… First pressure chamber, 42 …… Second pressure chamber, 43 …… Flow path, 44 …… Return spring, 45 …… Spring bearing, 46…
… Differential pressure generating means, 47 …… Guide, 48 …… Displacement body, 49 ……
Spring, 50 ... wall surface, 51 ... support rod, 52 ... nut,
53 …… Proportional solenoid valve, 54 …… Output shaft, 55 …… Passage, 56 ……
Detection rod, 57 …… coil, 58 …… displacement detector, 59 ……
Comparator, 60, 61, 64 …… signal line, 63 …… control driver, 66 …… hydraulic cylinder, 67 …… tank, 68,
69 …… End face, 73 …… Plunger, 74 …… Valve element, 75 …… Tension spring, 76 …… Movable valve seat, 77 …… Hydraulic pump, 78 …… Piston, 79,80 …… Pressure chamber, 81 ...... Spring, 82,83 ……
Passage, 84 ... proportional solenoid pressure reducing valve, 85 ... hydraulic source.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyo Kato, 650 Jinritsu-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory (56) References: Actual development Sho 60-62118 (JP, U)

Claims (14)

(57) [Claims] 1. A housing provided with a main fluid passage having an inflow port and an outflow port, a main valve arranged between the inflow port and the outflow port for communicating and blocking the inflow port and the outflow port, and the housing A back pressure chamber that is formed by an inner wall and a back portion of the valve body of the main valve and communicates with the inflow port through a throttle, an auxiliary passage that communicates the back pressure chamber and the outflow port, and opening and closing of the auxiliary passage. In a flow control valve device including a pilot valve for controlling and changing the fluid pressure of the back pressure chamber to operate the main valve, a differential pressure according to the flow rate of the main fluid passage, which is arranged in the main fluid passage. And a displacement body movable in the flow direction of the fluid in the main fluid passage, and a spring biasing the displacement body in a direction opposite to the flow direction of the fluid. The displacement body Depending on the differential pressure generated by the differential pressure generating means, which defines a flow path whose opening area increases with an increase in the moving stroke of the displacement body, between the wall surface of the main fluid passage and the differential pressure generated by the differential pressure generating means. A displacement detecting means for detecting the displacement of the displacement body and a control means for controlling the operating force of the pilot valve, and operating the operating force of the pilot valve according to a detection value output from the displacement detecting means. A flow control valve device, comprising: 2. The wall surface of the main fluid passage has a wall shape such that the opening area is a root function or a function approximate to the root function with respect to the moving stroke of the displacement body. 1) The flow control valve device as described above. 3. The control means comprises a passage means for guiding the upstream pressure of the displacement body of the differential pressure generating means to one end of the pilot valve spool and the downstream pressure to the other end of the pilot valve spool. The flow control valve device according to claim 1. 4. A fixed guide of the main valve body, which is provided on a wall portion forming a back pressure chamber of the housing, and projects toward the main valve body, and the auxiliary passage includes the main valve body and the main valve body. The fixed valve includes a through hole provided coaxially, and the pilot valve has a fixed valve seat integrated with a housing provided at one end of the through hole of the fixed guide.
The flow control valve device described. 5. The flow control valve device according to claim 1, wherein the main valve is a seat valve. 6. The flow control valve device according to claim 1, wherein the displacing bodies of the pilot valve and the differential pressure generating means are arranged coaxially with the main valve body interposed therebetween. 7. The displacement detection means includes a displacement detector for electrically detecting the displacement of the displacement body, and the correction means corresponds to the detected value detected by the displacement detector and the command operation amount for driving the pilot valve. A comparison calculator that performs a calculation including a comparison with a target displacement of the displacement body that performs the calculation.
The flow control valve device described. 8. A flow control valve device according to claim 1, wherein the drive means for driving the pilot valve comprises a proportional solenoid valve. 9. The flow control valve device according to claim 1, wherein the control means includes a spring means for urging the displacement body of the differential pressure generating means and the valve body of the pilot valve in the close direction. . 10. The flow control valve device according to claim 9, wherein the spring means is a tension spring arranged between the displacement body of the differential pressure generating means and the valve body of the pilot valve. 11. The flow control valve device according to claim 10, wherein the tension spring passes through a through hole of the main valve body. 12. The flow control valve device according to claim 1, wherein the displacement body of the differential pressure generating means also serves as a check valve. 13. The auxiliary passage includes a through hole provided coaxially with the main valve body, and the pilot valve has a movable valve seat integral with the main valve body provided at one end of the auxiliary passage. The flow control valve device according to claim 1. 14. A flow control valve device according to claim 1, wherein the drive means for driving the pilot valve is an oil pressure supply device for supplying oil pressure.