JPH08233136A - Control valve and hydraulic driving circuit - Google Patents

Abstract

PURPOSE: To realize a high accuracy and a stable control along the whole scope in the flow rate control and the pressure control, by connecting an inlet other than the first inlet of a control valve mechanism to a tank hole at first, as well as facing the pilot hole of a valve main body to a spring chamber, and after that, connecting all the inlets to the tank hole. CONSTITUTION: In a pressure matching condition, since the hydraulic pressure of a hydraulic line 25 is given to the other end face 8s of a spool 8 through a flow rate limiting choke 27, a pilot hole 10, and a spring chamber, and the hydraulic pressure at the first inlet 3i of control valve mechanisms 1x and 1y is given to a chamber one end face 8f of the spool 8 is faced, the hydraulic pressure of the hydraulic line 25 is bled off so as to make the differential pressure between the inlet and the outlet of the flow rate control valve 25 constant. That is, an outlet/inlet port 4i other than the first inlet 3i is connected to a tank hole 6, and the hydraulic pressure is returned to an oil tank. Consequently, a pressure control matching to a load pressure can be carried out. And after that, all the inlets 3 and 4 of the pressure control mechanisms 1x and 1y are connected to the tank hole 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control valve and a hydraulic drive circuit suitable for use in an injection molding machine or the like.

[0002]

2. Description of the Related Art Conventionally, a power matching circuit using a variable discharge pump, a flow rate matching circuit using an accumulator, a fixed pump and a differential relief valve have been used as a hydraulic drive circuit for an energy saving used in an injection molding machine. There are known pressure matching circuits and pump matching circuits using a plurality of different pumps.

As the pump matching circuit, a type of loading or unloading the pump on the large capacity side by an electric signal according to the magnitude of the command value, a differential relief valve for pressure matching and an unload valve are combined. Known types. An example of the latter is disclosed in, for example, Japanese Patent Laid-Open No. 57-57969. In the circuit disclosed in the publication, a spool that constantly closes a passage between a pump and a tank provided in a valve body by a spring on the secondary pressure chamber side is provided with a throttle that connects the circuit pressure chamber and the secondary pressure chamber at both ends of the spool. An unload valve is used which penetrates a choke and is provided with a passage for an external pilot pressure valve which causes a differential pressure between the circuit pressure chamber and the secondary pressure chamber in the secondary pressure chamber.

[0004]

However, in the conventional pump matching circuit in which the differential relief valve and the unload valve are combined, the relief valve and the unload valve to be used usually have a difference in dynamic characteristics. Since it is not possible to perform highly accurate and stable control over the entire range of the flow rate control and the pressure control, and the number of independent control valves increases, there is a problem that the cost and size of the entire circuit increase.

The present invention solves the problems existing in the prior art as described above. It is possible to perform highly accurate and stable control over the entire range of flow rate control and pressure control, and to reduce the cost of the entire circuit. An object is to provide a control valve and a hydraulic drive circuit that can be downsized and downsized.

[0006]

A control valve 1 according to the present invention
Is a valve body 2 provided with at least two or more inlets 3i, 4i (5i) and one or more tank inlets 6 (7), and coaxially has two or more spool members 8x, 8y (8z) integrally formed. Built-in spool 8 having, one end surface 8 of the spool 8
The pilot port 1 that communicates the chamber facing f with one inlet (first inlet) 3i, presses the other end surface 8s of the spool 8 with the spring 9, and faces the spring chamber housing the spring 9
When 0 and 10 are provided in the valve body 2 and the spool 8 is displaced against the spring force, first the inlets 4i other than the first inlet 3i
(5i) is connected to the tank port 6 (7), and then two or more control valve mechanisms 1x, 1y (1z) configured to connect all the inlets 3i, 4i (5i) to the tank port 6 are provided. It is characterized by being prepared as one.

Further, the hydraulic drive circuit 20 according to the present invention is
The control valve 1 was used, a small capacity fixed pump 21 using a hydraulic pump was connected to the first inlet 3i of the control valve 1, and a hydraulic pump was used for the inlets 4i (5i) other than the first inlet 3i. Connect a large-capacity fixed pump 22 (23),
Further, all the inlets 3i, 4i (5i) are connected via a flow control valve 24 to a hydraulic actuator, for example, a hydraulic line 25 leading to a hydraulic cylinder C provided in the injection molding machine M, and the hydraulic pressure is applied to the pilot ports 10, 10. Line 25
And a relief valve 26 are connected.
In this case, the pilot port 10 and the hydraulic line 25 are connected via the flow rate limiting choke 27. The flow rate limiting choke 27 can be built in the valve body 2.

[0008]

The control valve 1 according to the present invention has the function of integrating both the differential relief valve and the unload relief valve by integrally including two or more control valve mechanisms 1x and 1y (1z). Therefore, the hydraulic drive circuit 20 including the control valve 1 is switched to the pressure matching circuit and the pump matching circuit by the unload function.

In the case of pressure matching, the pressure oil discharged from the small-capacity fixed pump 21 is directly supplied to the flow rate control valve 24, and further, through the hydraulic line 25, the hydraulic cylinder C.
Is supplied to. At the same time, the large-capacity fixed pump 22
The pressure oil discharged from (23) is also directly supplied to the flow control valve 24 and further supplied to the hydraulic cylinder C via the hydraulic line 25. At this time, the oil pressure of the oil pressure line 25 is applied to the other end surface 8s of the spool 8 via the flow rate limiting choke 27, the pilot port 10 and the spring chamber, and the oil pressure at the first inlet 3i is applied to the one end surface 8f of the spool 8. Since it is applied to the facing chamber, the pressure oil in the hydraulic line 25 is bleed off so that the pressure difference between the inlet and outlet of the flow control valve 24 becomes constant. That is, the entrance / exit 4i other than the first entrance 3i
(5i) is connected to the tank port 6 (7), and the pressure oil is returned to the oil tank. Therefore, pressure control matching the load pressure becomes possible, and energy saving is achieved.

On the other hand, in the case of pressure control, the pressure oil discharged from the large-capacity fixed pump 22 (23) is returned to the oil tank with no load and the small-capacity fixed pump 21.
The pressure oil discharged from is also returned to the oil tank. As a result, pressure control is performed by the small-capacity fixed pump 21,
From this aspect, energy saving can be achieved.

Therefore, high speed and high responsiveness which cannot be obtained when the variable discharge pump is used (power matching circuit) are realized, and highly accurate and stable control is possible over the entire range of flow rate control and pressure control. . Further, since the unload circuit for the large capacity pump based on the command value control is eliminated and the two control valves are integrated, the cost and size can be reduced.

[0012]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the structure of the control valve 1 according to the present invention will be described with reference to FIGS. 1, 3 and 4.

In the figure, the control valve indicated by reference numeral 1 comprises a valve body 2. The valve body 2 has a first inlet / outlet 3 composed of a first inlet 3i and a first outlet 3o on the left side in FIG. 1, and a second inlet / outlet 4 composed of a second inlet 4i and a second outlet 4o on the right side.
Further, a tank port 6 is provided at an intermediate portion between the first entrance / exit 3 and the second entrance / exit 4. The valve body 2 has a spool 8
The spool 8 is allowed to have a constant displacement in the axial direction. The spool 8 is coaxial with the two spool members 8
x and 8y are integrally formed, and a spool passage 8c extending from one end face 8f to the first inlet / outlet 3 is provided. On the other hand, the other end surface 8s of the spool 8 is pressed by the spring 9. Also, the valve body 2
Has two pilot ports 10, 10 facing the spring chamber accommodating the spring 9. Therefore, the control valve 1 integrally includes two control valve mechanisms 1x and 1y. In this case, the spool 8
The configuration, positional relationship, etc. of the inlets / outlets 3, 4 and the tank port 6 are as follows. First, in the natural state, the spool 8 pressed by the spring 9 is located at the left end as shown in FIG.
As a result, the inlets and outlets 3 and 4 and the tank port 6 are connected to the spool 8
Is shut off by On the other hand, when the spool 8 is displaced against the spring force of the spring 9, the second inlet / outlet port 4 is first connected to the tank port 6, and then all the inlet / outlet ports 3 and 4 are connected to the tank port 6.
Connected to. The valve opening gain by the spool members 8x and 8y is set so that the spool member 8y side is larger than the spool member 8x side.

Next, a hydraulic drive circuit 20 in an injection molding machine using such a control valve 1 will be described with reference to FIGS.
Will be described with reference to.

In FIG. 1, M indicates an injection molding machine. In the injection molding machine M, reference numeral 51 is a heating cylinder having a screw 52 built therein. An injection nozzle 53 is provided at the tip of the heating cylinder 51, and a hopper 54 for material supply is provided at the rear of the heating cylinder 51. On the other hand, a hydraulic cylinder C that constitutes an injection cylinder is connected to the rear end of the heating cylinder 51. Further, the hydraulic cylinder C has a built-in double rod type piston 55, the front rod is coupled to the screw 52, and the rear rod is spline coupled to the rotary shaft 56s of the oil motor 56.

On the other hand, 20 is a hydraulic drive circuit for driving the injection molding machine M, and this hydraulic drive circuit 20 is for the control valve 1
Is provided. A small-capacity fixed pump (hydraulic pump) 21 is connected to the first inlet 3i of the control valve 1 facing the in-spool passage 8c, and a large-capacity fixed pump (hydraulic pump) 22 is connected to the second inlet 4i. Connect. Also,
An oil tank 31 is connected to the tank port 6. On the other hand, the first outlet 3o (first inlet 3i) is connected to the inlet of the flow rate limiting valve (electromagnetic proportional flow valve) 24, and the second outlet 4o.
The (first inlet 4i) is connected to the inlet of the flow rate limiting valve 24 via the check valve 32, and the outlet of the flow rate limiting valve 24 is connected to the hydraulic line 25. The hydraulic line 25 and the oil tank 31 are connected to the front oil chamber Cf and the rear oil chamber Cr of the hydraulic cylinder C via a switching valve (servo valve) 33. Further, the hydraulic line 25 is connected to the pilot port 10 via a flow rate limiting choke 27, and a relief valve (electromagnetic proportional pressure valve) 26 is further connected to the other pilot port 10. Note that FIG. 2 shows a hydraulic drive circuit 20 in which the control valve 1 is symbolized.

Next, the operation of the hydraulic drive circuit 20 including the function of the control valve 1 will be described with reference to FIGS.

The control valve 1 has two control valve mechanisms 1x and 1y.
Since it is provided as an integral part, it exhibits the function of integrating both the differential relief valve and the unload relief valve. Further, the hydraulic drive circuit 20 including such a control valve 1 can be switched to the pressure matching circuit and the pump matching circuit by the unload function.

First, the case where the fixed pumps 21 and 22 are not operated is shown in FIG. In this case, since pressure oil is not supplied to the control valve 1, the spool 8 pressed by the spring 9
Is located at the left end of the valve body 2. Therefore, both the first inlet / outlet 3 and the tank opening 6 and the second inlet / outlet 4 and the tank opening 6 are blocked by the spool 8 (spool members 8x and 8y).

On the other hand, when the fixed pumps 21 and 22 are in operation and the pressure is being matched, the operation is as follows. In this case, the spool 8 of the control valve 1 is displaced to the position shown in FIG. Therefore, in FIG. 1, the pressure oil discharged from the small-capacity fixed pump 21 is supplied to the inlet of the flow rate control valve 24 through the first inlet / outlet 3 of the control valve 1, and further the hydraulic line 25 and the switching valve 33. It is supplied to the hydraulic cylinder C via. At the same time, the pressure oil discharged from the large-capacity fixed pump 22 is supplied to the inlet of the flow rate control valve 24 via the second inlet / outlet 4 and the check valve 32, and further via the hydraulic line 25 and the switching valve 33. It is supplied to the hydraulic cylinder C. At this time, the hydraulic pressure of the hydraulic line 25 is applied to the other end surface 8s of the spool 8 via the flow rate restriction choke 27, the pilot port 10 and the spring chamber, and the hydraulic pressure at the first inlet / outlet 3 is transferred via the in-spool passage 8c. Since it is applied to the one end face 8f of the spool 8, the hydraulic line 25 is arranged so that the differential pressure at the inlet and outlet of the flow control valve 24 becomes constant.
Pressure oil is bleed off. That is, the second inlet / outlet 4 is connected to the tank port 6, and the pressure oil is returned to the oil tank 31. In addition, in FIG. 3, the arrow W shows the path | route of pressure oil. Therefore, pressure control that matches the load pressure is performed.

On the other hand, in the case of pressure control, it operates as follows. In this case, the spool 8 of the control valve 1 is displaced to the position shown in FIG. Therefore, in FIG. 1, the pressure oil discharged from the large-capacity fixed pump 22 is returned to the oil tank 31 with no load, and the small-capacity fixed pump 2 is supplied.
Part of the pressure oil discharged from No. 1 is also returned to the oil tank 31. As a result, pressure control by the small-capacity fixed pump 21 is performed. In FIG. 4, an arrow W indicates the path of pressure oil.

FIG. 5 shows the pressure-flow rate characteristic of the hydraulic drive circuit 20 using the control valve 1. In the figure, Ka, Kb,
Kc ... indicates characteristic lines corresponding to different set flow rates. Further, in the figure, the Lx portion shows a state where the large-capacity fixed pump 22 is unloaded, and the Ly portion shows a pressure control state by the small-capacity fixed pump 21.

Therefore, such a control valve 1 has the function of integrating both the differential relief valve and the unload relief valve, and the hydraulic drive circuit 20 functions as a pressure matching circuit and a pump matching circuit by the unload function. Since it can be switched, high speed and high responsiveness can be realized, and over the entire range of flow rate control and pressure control,
Highly precise and stable control can be performed. Moreover,
Since the two control valve mechanisms 1x and 1y are integrated, the cost and size of the entire circuit can be reduced.

Next, a control valve 1 according to a modified embodiment of the present invention.
The hydraulic drive circuit 20 will be described with reference to FIGS. 6 to 8.

FIG. 6 shows the control valve 1 shown in FIG.
The valve main body 2 has the same structure, but differs in that the positions of the first inlet / outlet 3 and the second inlet / outlet 4 are exchanged. Therefore, the in-spool passage 8c provided in the spool 8 is longer than in the control valve 1 shown in FIG. The hydraulic drive circuit 20 is the same as in the case of FIG. Therefore, it basically functions as in the embodiment of FIG. In FIG. 6, the same parts as those in FIG. 1 are designated by the same reference numerals to clarify the configuration.

Further, FIG. 7 shows the control valve 1 shown in FIG. 1 in which the outlets 3o and 4o of the valve body 2 are eliminated and the spool passage 8c provided in the spool 8 is eliminated. Therefore, the flow control valve 24 is directly connected to the fixed pump 21, and the check valve 32 is connected to the fixed pump 2.
2, the valve body 2 facing the one end face 8f of the spool 8 is further provided with a pressure port 2c.
That is, the chamber facing the one end face 8f of the spool 8 and the first inlet 3i
The control valve 1 is basically the same as the control valve 1 shown in FIG. On the other hand, flow restriction choke 2
7 illustrates a case where the valve body 2 is built in. In FIG. 7, the same parts as those in FIG. 1 are designated by the same reference numerals to clarify the configuration.

On the other hand, in FIG. 8, a third inlet / outlet 5 consisting of a third inlet 5i and a third outlet 5o is further provided next to the second inlet / outlet 4 in the control valve 1 shown in FIG. The third control valve mechanism 1z is added by providing the tank port 7 next to the No. 5 and providing the spool member 8z. Therefore, when the hydraulic drive circuit 20 is configured, the third inlet 5i is not connected to the control valve 1.
Is connected to a large capacity fixed pump 23, and an oil tank 31 is connected to the tank port 7.
o is connected to the inlet of the flow control valve 24 via the check valve 34. As a result, the fixed pump 23 can be additionally used in addition to the large-capacity fixed pump 22. In addition,
8, the same parts as those in FIG. 1 are designated by the same reference numerals to clarify the configuration.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The detailed configuration, shape, quantity, use, etc. can be arbitrarily changed without departing from the scope of the present invention.

[0030]

As described above, the control valve according to the present invention is a spool having a valve body provided with at least two or more inlets and one or two or more tank ports, and coaxially having two or more spool members integrally. With a built-in valve, the chamber facing one end surface of the spool communicates with one inlet (first inlet), the other end surface of the spool is pressed by a spring, and the pilot port facing the spring chamber containing the spring is located in the valve body. When the spool is provided and the spool is displaced against the spring force, first the inlets other than the first inlet are connected to the tank opening, and then all the inlets are connected to the tank opening. Since the control valve mechanism is integrally provided, and the hydraulic drive circuit according to the present invention uses the control valve, the following remarkable effects are obtained.

The control valve has a function of integrating both the differential relief valve and the unload relief valve, and
The hydraulic drive circuit can be switched to the pressure matching circuit and the pump matching circuit by the unload function, so high speed and high responsiveness can be realized, and highly accurate and stable control is performed over the entire range of flow rate control and pressure control. be able to.

Since the two control valve mechanisms are integrated,
The number of control valves can be reduced, and the cost and size of the entire circuit can be reduced.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic drive circuit including a control valve according to the present invention,

FIG. 2 is a hydraulic circuit diagram of the hydraulic drive circuit including a symbolized control valve,

FIG. 3 is a partial cross-sectional configuration diagram of a control valve at the time of pressure matching of the hydraulic drive circuit,

FIG. 4 is a partial cross-sectional configuration diagram of a control valve during pressure control of the hydraulic drive circuit,

FIG. 5 is a pressure flow rate characteristic diagram of the hydraulic drive circuit,

FIG. 6 is a hydraulic circuit diagram of a hydraulic drive circuit including a control valve according to a modified embodiment of the present invention,

FIG. 7 is a hydraulic circuit diagram of a hydraulic drive circuit including a control valve according to another modified embodiment of the present invention,

FIG. 8 is a hydraulic circuit diagram of a hydraulic drive circuit including a control valve according to another modified embodiment of the present invention,

[Explanation of symbols]

 1 control valve 1x control valve mechanism 1y control valve mechanism 1z control valve mechanism 2 valve body 3i inlet (first inlet) 4i inlet (second inlet) 5i inlet (third inlet) 6 tank port 7 tank port 8 spool 8x spool member 8y Spool member 8z Spool member 8f One end face 8s The other end face 9 Spring 10 Pilot port 20 Hydraulic drive circuit 21 Small capacity fixed pump 22 Large capacity fixed pump 23 Large capacity fixed pump 24 Flow rate limiting valve 25 Hydraulic line 26 Relief valve 27 Flow rate restriction choke C Hydraulic cylinder M Injection molding machine

Claims (6)

[Claims] 1. A valve body having at least two or more inlets and one or more tank openings, a spool having a coaxially two or more spool members integrally formed therein, and a chamber facing one end surface of the spool. One inlet (first inlet) is made to communicate, the other end surface of the spool is pressed by a spring, and a pilot port facing the spring chamber accommodating the spring is provided in the valve body to displace the spool against the spring force. When first, the inlets other than the first inlet are connected to the tank inlet, and after this,
A control valve comprising integrally two or more control valve mechanisms configured such that all inlets are connected to a tank port. 2. A valve body provided with at least two inlets and one or more tank inlets, and a built-in spool having two or more spool members integrally coaxially, and a chamber facing one end surface of the spool. One inlet (first inlet) is made to communicate, the other end surface of the spool is pressed by a spring, and a pilot port facing the spring chamber accommodating the spring is provided in the valve body to displace the spool against the spring force. When first, the inlets other than the first inlet are connected to the tank inlet, and after this,
Equipped with a control valve that integrally has two or more control valve mechanisms configured so that all the inlets are connected to the tank port, a small capacity hydraulic pump is connected to the first inlet, and a large capacity to the inlets other than the first inlet. Hydraulic drive characterized in that it is connected to the hydraulic pump, and all the inlets are connected to the hydraulic line leading to the hydraulic actuator via the flow control valve, and the hydraulic line and the relief valve are connected to the pilot port. circuit. 3. The hydraulic drive circuit according to claim 2, wherein the hydraulic pump is a fixed pump. 4. The hydraulic drive circuit according to claim 2, wherein the pilot port and the hydraulic line are connected via a flow rate limiting choke. 5. The hydraulic drive circuit according to claim 4, wherein the flow rate limiting choke is built in the valve body. 6. The hydraulic actuator is a hydraulic cylinder provided in an injection molding machine.
4. The hydraulic drive circuit according to 4 or 5.