JPS5922082B2 - fluid equipment - Google Patents

Description

[Detailed Description of the Invention] This invention controls the discharge volume of a variable discharge volume pump using a pressure control valve, so that the differential pressure before and after the variable flow rate adjustment orifice provided in the main circuit is controlled to be approximately constant. This invention relates to an energy-saving fluid device.

Conventionally, this type of fluid device has a main flow circuit 103 between an actuator 102 and a variable discharge pump 101 that always attempts to discharge the maximum flow rate, as shown in FIG. 1, for example.
A primary port 106 and a secondary port are provided between the main circuit 103 and a swash plate control cylinder 105 that controls the swash plate 101a as a variable discharge rate element of the variable discharge rate pump 101. When a two-port pressure control valve 111 having a pressure control valve 101 is connected and the switching valve 120 is in the switching position to control the flow rate, the pressure control valve 11
The pressures before and after the variable flow rate adjustment orifice 104 are transmitted to both ends of the spool 1120 of the pressure control valve 11, respectively.
1 is opened and closed according to the differential pressure before and after the variable flow rate adjustment orifice 104, and the line 115 between the pressure control valve 1110 secondary port 10γ and the swash plate control cylinder 105 has a throttle 116 with a small opening degree. line 11
γ to tank 118 (U.S. Pat. No. 28
No. 92312).

The fluid device has a variable flow rate adjustment orifice 104.
If the differential pressure around 0 becomes smaller than a certain value corresponding to the spring pressure of the spring 113 that presses the other end of the spool 112 of the pressure control valve 111, the spool 112 will move upward in FIG. 1 due to the spring force of the spring 113. , the space between the primary port 106 and the secondary port 101 is closed, and the fluid on the side opposite to the spring of the swash plate control cylinder 1050 is throttled 116 by the spring force of the spring 119.
The swash plate 101a is tilted toward the maximum tilt side to increase the discharge amount of the variable discharge amount pump 101, thereby increasing the differential pressure before and after the variable flow rate adjustment orifice 1040, while increasing the flow rate. Adjustable orifice 1
The differential pressure around 040 is the spool 112 of the pressure control valve 111.
If the spring pressure of the spring 113 at the other end is greater than a certain value, the spool 112 is moved downward in FIG.
Open the connection between the next port 10γ and the swash plate control cylinder 1.
050 Fluid from the mainstream circuit 103 is supplied to the anti-spring side through the line 115, and while compressing the spring 119 of the swash plate control cylinder 105, the swash plate 101a is positioned at the neutral position, and the discharge volume of the variable discharge volume pump 101 is adjusted. When controlling the flow rate, the differential pressure before and after the variable flow rate adjustment orifice 1040 is controlled to be constant regardless of the load (not shown) on the actuator 1020, and the discharge volume and discharge pressure of the variable discharge volume pump 101 are controlled to be variable by flow rate adjustment. Control is performed according to the opening degree of the orifice 104 and the load on the actuator 102.

Therefore, the above fluid device has the advantage of low power loss and relatively energy saving.

However, in the above fluid system, the pressure control valve 111 is of a two-point type, and the line 115 between the pressure control valve 1110 secondary port 10γ and the swash plate control cylinder 105
into tank 1 via line 111 with aperture 116
18, in order to position the swash plate 101a on the neutral side, the pressure control valve 111 is opened and the main circuit 10 is connected to the
3 to the swash plate control cylinder 105, there is a completely wasteful leakage flow from the throttle 116 to the tank 118, so there is a drawback that the energy saving effect is not sufficient.

Further, as described above, in the above fluid system, when fluid is being supplied from the main circuit 103 to the swash plate control cylinder 105 in order to position the swash plate 101a on the neutral side, there is leakage from the throttle 116 to the tank 118. Therefore, the speed at which the swash plate 101a is positioned to the neutral side becomes slow, resulting in poor responsiveness in the direction of decreasing the discharge amount of the variable discharge amount pump 101. When the pressure control valve 111 is closed to increase the pressure,
Since the fluid on the pressure spring side of the swash plate control cylinder 105 is discharged to the tank 118 only through the throttle 116 which has a small opening degree, the speed at which the swash plate 101a returns to the maximum inclination side is slow, making it possible to vary the discharge amount. There is also a drawback that the responsiveness in the direction of increasing the discharge amount of the pump 101 is also poor.

The purpose of this invention is to eliminate the above-mentioned conventional drawbacks, and maintain the energy-saving effect of eliminating power loss by controlling the discharge volume and discharge pressure of a variable discharge volume pump according to demand. This eliminates the conventional leakage flow rate, reduces power loss, and
To improve responsiveness to increases and decreases in the discharge volume of the variable discharge volume pump, and when driving multiple actuators, if the required flow rate of all the multiple actuators is within the maximum discharge flow rate of the variable volume pump, it is possible to By controlling the differential pressure before and after each variable flow rate adjustment orifice corresponding to each of the actuators to be approximately constant, it is possible to compensate for the pressure of all actuators, while the required flow rate of one or more actuators as a whole is the maximum discharge flow rate of the variable discharge pump. In the case where the pressure difference exceeds the above, the pressure difference before and after the variable flow rate adjustment orifice for a specific actuator is preferentially controlled to be substantially constant, so that the pressure can be compensated preferentially for the specific actuator.

For this reason, the fluid device of the present invention has a restrictor pressure reduction control between the variable discharge pump and the actuator, which has a characteristic of biasing the variable discharge rate control element in the direction of maximum inclination to maintain the discharge rate at the maximum value. A pressure reduction control section and a variable flow rate adjustment orifice of a priority type pressure control valve having a section and a branch control section are sequentially connected from the upstream side, and the variable flow rate adjustment orifice is connected to one end of the spool of the priority type pressure control valve. The spool of the priority type pressure control valve is configured to transmit pressure at the front of the variable flow rate adjustment orifice to a back pressure chamber compressed with a spring at the other end of the spool. In response to the differential pressure between the two pressures transmitted to both ends, the differential pressure before and after the variable flow rate adjustment orifice is preferentially controlled to be approximately constant, and furthermore, a flow control section different from the flow control section of the priority type pressure control valve is used. Another variable flow rate adjustment orifice is connected between the actuator, and one end of the spool of a three-port pressure control valve having at least a primary port, a secondary port, and a tank port is connected in front of the variable flow rate adjustment orifice. The spool of the pressure control valve is configured to transmit the pressure at the rear of the variable flow rate adjustment orifice to a back pressure chamber compressed by a spring at the other end of the spool, and both pressures transmitted to both ends of the spool of the pressure control valve are In response to the differential pressure of By making it switchable and connectable to a tank line connected to the pump, the discharge amount of the variable discharge amount pump can be controlled, and the differential pressure before and after the variable flow rate adjustment orifice can be controlled to be approximately constant. By making it possible to control the discharge volume and discharge pressure of a variable discharge volume pump according to demand without requiring unnecessary leakage flow, it is possible to reduce power loss and increase and decrease the discharge volume of a variable discharge volume pump. In addition, if the required flow rate of multiple actuators as a whole exceeds the maximum discharge flow rate of the variable discharge rate pump, a variable flow rate adjustment orifice connected to the pressure reduction control part of the priority type pressure control valve is used. It is characterized by preferentially controlling the differential pressure across the front and rear at a constant level, and preferentially performing pressure compensation on a specific actuator corresponding to the variable flow rate adjustment orifice.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

In FIG. 2, a variable discharge amount pump 1 includes a cylinder 4 that displaces a variable discharge amount control element 2 such as a swash plate, using a trunnion shaft 3 as a fulcrum, and a spring 5 is installed in the cylinder 4. .

The spring 5 is installed at a position that urges the variable discharge amount control element 2 in the direction of maximum inclination, so that the pump 1
has the characteristic of always trying to maintain the discharge amount at the maximum value.

Further, the suction side of the pump 1 is connected to a tank γa via a circuit 6.
Also, the discharge circuit 8 connected to the discharge side is connected to the primary port 301 of the priority type pressure control valve 43, the first control circuit 8X is connected to the pressure reduction port 302 of the pressure control valve 43, and the second The control circuit 8z is connected to the pressure control valve 430 and the branch port 303, respectively.

The second control circuit 8z is connected to the actuator 50 via the flow direction control valve 10.

On the other hand, the flow rate directional control valve 10 is constructed by a block 1, as specifically shown in FIG. 3, which is a cross-sectional view of a part of FIG.
1, a P port P that connects the second control circuit 8z to the second control circuit 8z, two A ports A and B ports B that connect the actuator 50, a tank port T that connects the tank 1b, and a port that connects the pilot line 13. 14, and three lands 15, 16, 1γ type movable valve 18 inside.
is provided to form a center all port block shape.

Furthermore, the flow direction control valve 10 is a movable valve 18 as shown in FIG.
By displacing the central land 150, a variable flow rate adjustment orifice 19 is formed between the corners on both sides of the central land 150 and the block, and a feedback passage 2 having one end opened at the rear of the variable flow rate adjustment orifice 19 is formed.
0 is communicated with the port 14.

A vent switching portion 21 is formed on the outer periphery of the land 11 of the movable valve 18, and the vent switching portion 21 is formed of the outer periphery and an annular groove.
The vent passage 22, which is formed so as to communicate with the feedback passage 20, is opened and closed in the middle by movement of the vent switching section 21.

That is, the vent switching section 21 opens the vent passage 22 when the movable valve 18 is in the neutral position, and closes the vent passage 22 when the movable valve 18 is displaced from the neutral position.

Further, the pressure control valve 30 is of a three-port type, as shown in FIGS. 2 and 3, and has three main ports 24,
25, 26, and further a pilot port 21 and a drain port 28, the primary port 24 is connected to the second control circuit 8Z, the secondary port 25 is connected to the line 29, and the tank port 26 and drain port 28 are connected to the line 29. tank line 4
0, the pilot port 2γ is connected to the pilot line 1
3 are connected to each other.

Furthermore, a spool 31 is installed inside the no-Uji puffer fish 23, and the force of a spring 33 in a back pressure chamber 32 formed so as to communicate with the pilot port 21 is applied to the spool 31, so that the primary port 24 and the Next port 25
The space between the secondary port 25 and the tank port 26 is kept normally closed, and the space between the secondary port 25 and the tank port 26 is kept normally open.

The pilot valve 80 has a valve body 35 pressed against a valve seat 34 formed between the back pressure chamber 32 and the drain port 28 by the force of a spring 36.

Further, the line 29 connected to the secondary port 25 is connected to the opposite side of the cylinder 40 to the spring, and the line 39 connected to the spring side of the cylinder 4 is opened to the tank 1a.

On the other hand, as specifically shown in FIG. 5, the priority type pressure control valve 43 has a throttle pressure reduction control section Y and a branch flow control section Z between both corners of the land 46' of the spool 46 and the corner of the housing 300. By the displacement of the spool 46 against the spring 41 compressed in the back pressure chamber 48, when the throttle depressurization control part Y is in the controlled state with an opening smaller than the virtual line Y', the shunt control part 2 is not controlled. In contrast to this, when the branch flow control section Z is in a controlled state with an opening smaller than the virtual line Z', the throttle pressure reduction control section Y is in a non-controlled state. It has a structure that allows you to do it.

In the pressure control valve 43, the second control circuit 8Z is connected to the actuator 50 via the branch control section Z, while the first control circuit 8X communicating with the actuator 50X is throttled and the pressure reduction control section Y is connected. The back pressure chamber 48 on one end side of the spool 46 of the pressure control valve 43 and the rear of the flow rate adjustment variable orifice 19X of the flow direction control valve 10X provided in the first control circuit 8X are While communicating through the circuit 49, the other end of the spool 46 is connected to the front side of the variable flow rate adjustment orifice 19X through a passage '305.

The preferential type pressure control valve 43 shown in FIG.
The spool 46 is moved forward and backward by opposing the load pressure at the rear of the variable flow rate adjustment orifice 19X led to the back pressure chamber 48 and the spring pressure of the spring 4γ against the pressure at the front X.
The differential pressure before and after the variable flow rate adjustment orifice 19X is controlled to be approximately constant by the control action of the throttle pressure reduction control unit The excess fluid is diverted to the circuit 8Z, and the actuator 50 is operated with this surplus fluid.

Note that the back pressure chamber 48 of the priority type pressure control valve 43 is also provided with a pilot valve 80 having exactly the same structure as the pilot valve 80 provided in the back pressure chamber 32 of the pressure control valve 30.

The fluid device having the above configuration operates as follows.

Now, the basic operating state in which the flow rate directional control valve 10y is located at the neutral position and the flow rate directional control valves 10X, 10 are both located at the switching position will be explained in the following cases.

(2) When the total required flow rate of the actuators 50X and 50, that is, the total required flow rate of the variable flow rate adjustment orifices 19X and 19, is smaller than the maximum discharge flow rate of the variable discharge pump 1.

In this case, as shown in FIGS. 2 and 5, the spool 46 of the priority type pressure control valve 43 moves back and forth in the axial direction in response to the differential pressure of the fluid acting on both ends of the spool 46. , by controlling the opening degree of the throttle pressure reduction control section Y or the opening degree of the branch flow control section 2, the differential pressure before and after the variable flow rate adjustment orifice 19X is controlled to a constant value corresponding to the spring pressure of the spring 41 of the back pressure chamber 48. do.

On the other hand, surplus fluid discharged through the priority type pressure control valve 430 diversion control section Z and diversion port 303 is supplied toward the variable flow rate adjustment orifice 19 through the second control circuit 8Z, but the pressure control valve 430 The valve 30 operates as described below, and the variable discharge amount pump 1 is adjusted so that the differential pressure before and after the variable flow rate adjustment orifice 190 corresponds to the spring pressure of the spring IJ ring 33 of the back pressure chamber 32 shown in FIG. Control the discharge amount.

That is, the pressure in front of the variable flow rate adjustment orifice 19 acts on the primary port side 24 at one end of the spool 31 of the pressure control valve 30, and the pressure in front of the variable flow rate adjustment orifice 19 acts on the back pressure chamber 32 at the other end of the spool 31. Rear pressure and spring 3
3 acts, and the spool 31 moves forward and backward in the axial direction.

Therefore, when the pressure difference between the fluid pressure on the primary port 24 side of the pressure control valve 300 and the fluid pressure on the back pressure chamber 32 side is equal to or less than the spring pressure of the spring 33, the pressure control valve 30 is connected to the secondary port 25 and the tank port 26. The fluid on the opposite side of the cylinder 40 to the spring is discharged to the tank IC, and the variable discharge amount control element 2 is tilted toward the maximum flow rate discharge side, that is, the maximum inclination side, thereby increasing the discharge amount.

On the other hand, the pressure difference between the fluid pressure on the primary port 24 side of the pressure control valve 300 and the fluid pressure on the back pressure chamber 32 side causes the spring 3
When the spring pressure is equal to or higher than the spring pressure of 3, the pressure control valve 30 connects the primary port 24 and the secondary port 25, and supplies the fluid of the second control circuit 8Z to the opposite spring side of the cylinder 40 through the line 29. The discharge amount variable control element 2 is positioned on the neutral side, that is, on the minimum slope side, to reduce the discharge amount of the variable pump 1.

In this manner, the pressure control valve 30 controls the secondary port 25 to the primary port 24 in response to the fluid pressure difference between the primary port 24 side and the back pressure chamber 32, that is, the differential pressure before and after the variable flow rate adjustment orifice 190. Alternatively, it can be switched and connected to the tank port 26 to control the discharge amount and discharge pressure of the variable pump 1 according to the opening degree and load of the flow rate adjustment variable orifice 19 to prevent unnecessary fluid from being discharged.
The differential pressure before and after is controlled to a constant value corresponding to the spring pressure of the spring 33.

Therefore, power loss is reduced.

Furthermore, during the operation of the pressure control valve 30, when the fluid on the side opposite to the spring of the cylinder 40 is discharged to the tank γC in order to increase the discharge amount of the variable pump 1, the fluid is transferred to the secondary port 25 of the pressure control valve 300. and tank port 26
Since the moving speed of the cylinder 4 is fast, the responsiveness of the variable pump 1 in the direction of increasing the discharge amount is better than that of the conventional two-point type pressure control valve 111 as shown in FIG. This is faster than using a small restrictor 116 to drain the fluid on the opposite side of the cylinder to the tank.

In addition, when supplying fluid to the opposite spring side of the cylinder 4 in order to reduce the discharge amount of the variable pump 1, the fluid is supplied from the second control circuit 8Z through the pressure control valve 300 primary port 24, secondary port 25 and line 29. Transfer fluid to cylinder 4
Since the supply is made to the anti-spring side of the
Since there is no leakage flow discharged into the tank through the throttle 116 as in the conventional one shown in the figure, the moving speed of the cylinder 4 becomes faster, and the responsiveness of the variable pump 1 in the direction of decreasing the discharge amount becomes faster. There is.

Furthermore, the opening degree between the secondary port 25 and the primary port 24 or tank port 26 of the pressure control valve 300 is determined by a constant value corresponding to the differential pressure before and after the variable flow rate adjustment orifice 190 and the spring force of the spring 33. The response of the variable pump 1 in the direction of increasing and decreasing the discharge amount is extremely high.

Further, as described above, since there is no leakage flow rate discharged into the tank from between the secondary port 25 of the pressure control valve 30 and the cylinder 4, power loss is reduced.

(2) When the total required flow rate f of the actuators 50X and 50, that is, the total required flow rate of the variable flow rate adjustment orifices 19X and 19, is greater than the maximum discharge flow rate of the variable discharge rate pump 1;

In this case (see FIG. 5), the priority type pressure control valve 43 is
Operating as described above, the pressure is compensated preferentially so that the differential pressure before and after the variable flow rate adjustment orifice 19X becomes a constant value corresponding to the spring pressure of the spring 4γ, and excess fluid is discharged from the diversion port 303.

The surplus fluid is supplied to the variable flow rate adjustment orifice 19, but since the flow rate of the surplus fluid is insufficient, the differential pressure across the variable flow rate adjustment orifice 190 becomes lower than a predetermined constant value.

Therefore, as shown in FIG. 3, the differential pressure between the flesh pressures transmitted to both ends of the spool 31 of the pressure control valve 30 becomes lower than the spring pressure of the spring 33 of the back pressure chamber 32, causing the spool 31 to move as shown in FIG. By displacing it to the left, the secondary port 25 and tank port 26 are communicated, and the variable discharge amount element 2 is tilted toward the maximum discharge side, thereby causing the variable discharge pump 1 to discharge the maximum flow rate.

In this way, in this fluid system, when the total required flow rate is larger than the maximum discharge flow rate of the variable discharge rate pump 1, the priority type pressure control valve 430 reduces the pressure while causing the variable discharge rate pump 1 to discharge the maximum flow rate. The differential pressure before and after the variable flow rate adjustment orifice 19X on the port) 302 side is preferentially controlled to be constant, and the actuator 50X connected to the variable flow rate adjustment orifice 19X is preferentially compensated for pressure to accurately control the speed. In addition, excess fluid from the priority type pressure control valve 430 branch port 303 is supplied to other actuators 50.

In other words, this fluid device can compensate the pressure of the specific actuator 50X preferentially over other actuators 50 when the discharge flow rate of the variable discharge rate pump 1 is insufficient.

Note that while the pressure control valve 30.43 is in operation,
It is assumed that the pilot valve 80.80 is closed because the pressure in the back pressure chamber 32.48 is below its set pressure.

The embodiment shown in FIG. 6 has the main structure shown in FIG. The second control circuits 8X and 8Z are configured as closed circuits, and in the case of chart reading, the fluid controlled by the low pressure relief valve 44 is supplied to the suction side of the variable pump 1 by the charge pump 45.
However, since the replenishment flow rate only corresponds to the amount of leakage in a closed circuit, it is effective in that the volume of the tank can be made smaller than in an open circuit.

As is clear from the above description, the fluid device of the present invention is provided between a variable discharge rate pump and an actuator, which has a characteristic of biasing the variable discharge rate control element in the direction of maximum inclination to maintain the discharge rate at the maximum value. The pressure reduction control part and the variable flow rate adjustment orifice of a priority type pressure control valve having a throttle pressure reduction control part and a branch flow control part are connected sequentially from the upstream side, and one end of the spool of the priority type pressure control valve is connected in sequence from the upstream side. The configuration is such that the pressure at the front of the variable flow rate adjustment orifice is transmitted, while the pressure at the rear of the variable flow rate adjustment orifice is transmitted to a back pressure chamber compressed with a spring at the other end of the spool, and the pressure at the rear of the variable flow rate adjustment orifice is transmitted. The spool of the valve is made to respond to the differential pressure between the two pressures transmitted to both ends of the valve, and the differential pressure before and after the variable flow rate adjustment orifice is preferentially controlled to be substantially constant, and furthermore, the preferential type pressure control valve is divided into two types. Another variable flow rate adjustment orifice is connected between the control unit and the other actuator, while the above flow rate adjustment is connected to one end of the spool of a three-port pressure control valve having at least a primary port, a secondary port, and a tank port. The configuration is such that the pressure at the front of the variable orifice is transmitted, and the pressure at the rear of the flow rate adjustment variable orifice is transmitted to a back pressure chamber compressed with a spring at the other end of the spool, and the spool of the pressure control valve is connected to both ends thereof. In response to the differential pressure between the two pressures transmitted to the cylinder, a cylinder connected to the secondary port and driving the variable discharge amount control element is connected to the mainstream circuit in front of the variable flow rate adjustment orifice connected to the primary port. and a tank line connected to the tank port, so that the discharge volume of the variable discharge volume pump can be controlled and the differential pressure before and after the variable flow rate adjustment orifice can be controlled to be approximately constant. Since the discharge volume and discharge pressure of the variable discharge volume pump can be controlled according to demand without requiring unnecessary leakage flow, power loss can be reduced, and the discharge volume of the variable discharge volume pump can be controlled as required. Flow rate adjustment connected to the pressure reduction control section of the priority type pressure control valve can quickly control the increase and decrease of Various effects can be achieved by preferentially controlling the differential pressure across the variable orifice to a constant value and preferentially compensating the pressure of a specific actuator connected thereto.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional fluid device, FIG. 2 is a circuit diagram of an embodiment of the present invention, FIGS. 3 and 5 are partial sectional views of FIG. 2, and FIG. 4 is a flow rate directional control valve 10. FIG. 6 is a circuit diagram of a modified example. DESCRIPTION OF SYMBOLS 1...Variable discharge amount pump, 2...Variable discharge amount control element, 4...Cylinder, 1a, γb
...Evening, 8.8a, 8b... Mainstream circuit, 19X, 19... Variable flow rate adjustment orifice, 24... Primary port, 25・・・・・・
Secondary port, 26...tank port, 3043
......Pressure control valve, 31...Spool,
32... Back pressure chamber, 33... Spring.

Claims (1)

[Claims] 1. The discharge circuit 8 of the variable discharge pump 1, which has the characteristic of biasing the variable discharge rate control element 2 in the direction of maximum inclination to maintain the discharge rate at the maximum value, is equipped with a throttle pressure reduction control section Y and a diversion control section Z.
A first flow rate adjustment variable orifice 19X is provided in the first control circuit 8X via the pressure control valve 430 pressure reduction control section Y, and a first flow rate adjustment variable orifice 19X is provided downstream of the variable orifice 19X. While connecting the first actuator 50X, the spool 46 of the priority type pressure control valve 43
The pressure at the front side of the first variable flow rate adjustment orifice 19X is transmitted to one end, while the pressure at the rear side of the first variable flow rate adjustment orifice 19X is transmitted to the back pressure chamber 48 in which the spring 4γ is compressed at the other end of the spool 46. As a configuration for transmitting pressure, the spool 46 of the priority type pressure control valve 43 is made to respond to the differential pressure between both pressures transmitted to both ends thereof, so that the differential pressure before and after the first flow rate adjustment variable orifice 19X is kept approximately constant. furthermore, the priority type pressure control valve 430 branch flow control section Z
A second flow rate regulating orifice 19 is connected to the second control circuit 8z via the primary ports 24 and 2.
While transmitting the pressure at the front of the second flow rate adjusting orifice 19 to one end of the spool 31 of the three-port pressure control valve 30 having the next port 25 and the tank port 26,
The pressure at the rear of the second variable flow rate adjustment orifice 19 is transmitted to the back pressure chamber 32 in which the spring 33 at the other end of the spool 31 is compressed, and the spool 31 of the pressure control valve 30 is transmitted to both ends thereof. The cylinder 4, which drives the variable discharge control element 2 connected to the secondary port 25 in response to the differential pressure between the two pressures, is controlled by the second flow rate adjusting orifice 19 connected to the primary port 24. 2nd in front
The control circuit 8Z and the tank line connected to the tank port 26 can be switchably connected to control the discharge volume of the variable discharge volume pump 1, thereby adjusting the differential pressure before and after the second flow rate adjustment variable orifice 190. A fluid device characterized by being able to be controlled substantially constant.