JP3690839B2 - Pressure control device for flow control of negative control variable displacement pump hydraulic circuit - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a hydraulic circuit of a negative control type variable displacement pump, and more particularly to a pressure generating device for controlling the flow rate thereof.
[0002]
[Prior art]
In general, a flow control pressure generator (hereinafter referred to as a flow control pressure generator or simply a pressure generator) of a negative control type variable displacement pump hydraulic circuit, as shown in FIG. The pressure generator 18 is provided on the outlet side of the center bypass passage 16a of the control valve 16 that supplies the pressure oil 12 to the actuator 14 and the like, and the upstream pressure (control pressure) p of the pressure generator 18 is set to the signal line 20. The discharge flow rate of the variable displacement pump 10 is negatively controlled by being applied to the pump controller 10a via The pressure oil (hydraulic oil) in the pressure generator 18 is discharged from the tank line 22 into the tank 24. Here, the pressure generator 18 has a throttle function part 18a and a relief function part 18b. As shown in FIG. 4, when the control pressure pc generated by the throttle function part 18a exceeds a predetermined value p ', the relief function part 18a is provided. The part 18b is activated to protect the controller 10a.
[0003]
In other words, the pressure generator 18 is formed of a poppet 34 that is slidably disposed with respect to the cap 32 in the casing 30 with reference to FIG. More specifically, the poppet 34 has a front pressure chamber 36 and a rear pressure chamber 40 communicated with the front pressure chamber 36 through a communication hole 38, and the pump line 12 is connected to the front pressure chamber 36. The tank line 22 is connected via the seat surface 42, and the tank line 22 is connected via the casing pocket 44 and the orifice 46 (that is, the aforementioned throttle function part 18a). The rear pressure receiving section 48 is set to be larger than the area a of the rear pressure receiving section 48, and the rear pressure receiving section 48 is loaded with a spring 50 having a predetermined urging force.
[0004]
Therefore, according to the pressure generator 18 configured as described above, when the discharge pressure oil from the pump 10 flows into the tank line 22 through the pump line 12, the front pressure chamber 36, the orifice 46 and the casing pocket 44, As described above (see FIG. 4), a pressure p corresponding to the flow rate Q is generated in the front pressure chamber 36. Then, this pressure is applied as a control pressure pc to the pump controller 10a through the communication hole 38, the rear pressure chamber 40, and the signal line 20. In this case, if an excessive flow Q passes through the orifice 46 and an excessive pressure p is generated in the front pressure chamber 36, the differential pressure related to both areas A and a increases, and the poppet 34 is attached to the spring 50. The hydraulic oil (pump discharge pressure oil) is bypassed directly from the seat surface 42 into the casing pocket 44 (without going through the orifice 46). That is, as described above, when the control pressure pc generated in the throttle function unit 18a exceeds the predetermined value p ′, the relief function unit 18b including the spring 50 and the like is activated to protect the controller 10a.
[0005]
Thus, according to this type of pressure generator, the flow control of the negative control type variable displacement pump hydraulic circuit can be reliably achieved with a relatively simple configuration. Therefore, this type of pressure generator is widely used especially for flow control in mother machines such as construction machines.
[0006]
[Problems to be solved by the invention]
However, the conventional pressure control device for flow control has the following problems.
[0007]
That is, in the conventional pressure generating device, as described above, the control pressure is such that the discharge pressure oil from the pump is discharged from the front pressure chamber of the pressure generating device through the orifice (throttle function portion) in the casing pocket. It is generated by jetting out. However, in this configuration, a large differential pressure (pressure loss) is required before and after the orifice. In other words, the jet flow from the orifice must be set at a high speed. For this reason, in the conventional pressure generator, the high-speed jet from the orifice collides with the casing pocket wall and generates an impact sound. As a result, a mother machine such as a construction machine equipped with this type of pressure generator is used. The problem of noise generation was pointed out. In view of the recent environmental problems, there has been a strong demand for improvement.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure control device for flow control of a negative control variable displacement pump hydraulic circuit that can suppress noise (impact sound) and can be configured relatively easily.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a flow control pressure generator for a negative control type variable displacement pump hydraulic circuit according to the present invention comprises:
Controls the discharge flow rate of the variable displacement pump by introducing the upstream pressure of the pressure generator provided on the outlet side of the center bypass passage of the control valve that supplies the discharge pressure oil of the variable displacement pump to the pump controller of the variable displacement pump. In the pressure generator in the negative control type variable displacement pump hydraulic circuit, the pressure generator is
A poppet having a communication hole that forms a seat surface facing the front pressure chamber formed in the casing into which pressure oil from the control valve is introduced;
A cap having a front and a rear inner peripheral surface that is screwed and fixed to the casing from the opposite side of the front pressure chamber of the casing and slidably supports the outer peripheral surface of the poppet;
A rear pressure chamber for storing a spring for pressing the seat surface toward the casing is formed at the rear portion of the communication hole of the poppet,
A casing communicating with the back pressure chamber formed between the outer peripheral portion of the poppet and the inner peripheral portion of the cap excluding the front and rear inner peripheral surfaces and the back pressure chamber and the tank line. A second orifice formed between the front inner peripheral surface and the poppet outer peripheral portion is provided between the pocket and the pocket.
In that case, the flow passage areas of the first orifice and the second orifice can be sequentially increased from the upstream side to the downstream side.
[0010]
[Action]
In the present invention, the throttle function portion of the pressure generator is formed from a plurality of stages of orifices (orifices), and the flow passage area is set to increase sequentially from the upstream side to the downstream side. Therefore, according to the present invention, even if the differential pressure of the entire throttle function section is the same as the conventional one, the differential pressure across the individual orifices constituting the throttle function section is reduced, and as a result, the jet flow from the final stage orifice The speed can be set to be much slower than before. That is, it is clear that the impact sound that the jet from the orifice collides with the casing pocket wall portion is suppressed, and as a result, the noise in the mother machine such as a hydraulic machine is suppressed. The pressure generator of the present invention has the advantage that it can be constructed relatively easily.
[0011]
【Example】
Next, embodiments of a pressure control device for flow control of a negative control type variable displacement pump hydraulic circuit according to the present invention will be described in detail with reference to the accompanying drawings. For convenience of explanation, the same components as those of the conventional configuration shown in FIGS. 3 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.
[0012]
First, the basic configuration of the pressure generator according to the present invention is the same as that of the conventional one (FIG. 5). That is, although it overlaps, when it demonstrates again, in FIG. 1, the pressure generator 18 of this invention is formed in the casing 30 from the poppet 34 arrange | positioned so that sliding with respect to the cap 32 is possible. The poppet 34 has a front pressure chamber 36 and a rear pressure chamber 40 communicated with the front pressure chamber 36 through a communication hole 38, and the pump line 12 has a seat surface 42 with respect to the front pressure chamber 36. The tank line 22 is connected via the casing pocket 44 and the throttle function part 60 (which will be described in detail later). The area A of the seat surface 42 is set larger than the area a of the rear pressure receiving portion 48 of the poppet 34, and a spring 50 having a predetermined urging force is loaded on the rear pressure receiving portion 48.
As shown in FIGS. 1 and 2, the cap 32 slidably supports the outer peripheral surface of the poppet 34 on the front and rear inner surfaces thereof, and has a cylindrical body having a front inner peripheral surface. And a member having a rear inner peripheral surface screwed inside the right end portion of the cylindrical body. Here, the said cylindrical body and member comprise the 1st member in this invention, and a 2nd member. A concave portion communicating with the rear pressure chamber 40 is formed in the member (second member), and a flow control pressure is led from the concave portion to the pump controller 10a as an upstream pressure of the pressure generator .
[0013]
Accordingly, in this configuration, when the discharge pressure oil from the pump 10 flows out to the tank line 22 through the pump line 12, the front pressure chamber 36, the throttle function unit 60, and the casing pocket 44, the flow rate Q (FIG. 4 is generated in the front pressure chamber 36, and this pressure is applied as a control pressure pc to the pump controller 10a via the communication hole 38, the rear pressure chamber 40, and the signal line 20. In this case, if an excessive flow rate Q passes through the orifice 46 and an excessive pressure p is generated in the front pressure chamber 36, this excessive pressure p increases the differential pressure related to both areas A and a. The poppet 34 moves to the right in the drawing against the biasing force of the spring 50 (that is, the relief function is activated), and the hydraulic oil is bypassed directly from the seat surface 42 into the casing pocket 44, so that Can be prevented.
[0014]
However, in the present invention, in the above-described configuration, the above-described throttle function unit 60 is formed from first and second orifices (throttles) 60a and 60c arranged in series in the flow path direction (see FIG. 2). These orifices 60a and 60c are set and configured such that the flow passage area is larger on the downstream side (second orifice 60c) than on the upstream side (first orifice 60a). A back pressure chamber 60b is formed between the orifices 60a and 60c.
[0015]
Therefore, according to the present invention, even if the differential pressure of the entire throttle function section 60 is the same as the conventional one, the differential pressure before and after the individual (first and second) orifices 60a and 60c constituting the throttle function section 60. As a result, the jet velocity from the final stage (second) orifice 60c is set to be much lower than in the prior art. That is, the impact sound that the jet flow from the orifice (throttle function part) collides with the casing pocket wall part is suppressed, and as a result, the noise in the mother machine such as a hydraulic machine is suppressed.
[0016]
In addition, the pressure generator of the present invention has an advantage that it can be configured relatively easily (without greatly changing the conventional structure). In this embodiment, the throttling function portion is composed of two front and rear orifices 60a and 60c, but the present invention is not limited to this, that is, it may be composed of three or more orifices. In this case, it is preferable that the flow path area of the orifice is set to increase sequentially from the upstream side to the downstream side.
[0017]
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and many design changes can be made without departing from the spirit of the present invention.
[0018]
【The invention's effect】
As described above, the pressure control device for flow control of the negative control type variable displacement pump hydraulic circuit according to the present invention includes:
Controls the discharge flow rate of the variable displacement pump by introducing the upstream pressure of the pressure generator provided on the outlet side of the center bypass passage of the control valve that supplies the discharge pressure oil of the variable displacement pump to the pump controller of the variable displacement pump. In the pressure generator in the negative control type variable displacement pump hydraulic circuit, the pressure generator is
A poppet having a communication hole that forms a seat surface facing the front pressure chamber formed in the casing into which pressure oil from the control valve is introduced;
A cap having a front and a rear inner peripheral surface that is screwed and fixed to the casing from the opposite side of the front pressure chamber of the casing and slidably supports the outer peripheral surface of the poppet;
A rear pressure chamber for storing a spring for pressing the seat surface toward the casing is formed at the rear portion of the communication hole of the poppet,
A first orifice communicating with the back pressure chamber formed between the outer peripheral portion of the poppet and the cap inner peripheral portion excluding the front and rear inner peripheral surfaces from the communication hole, and a casing communicating with the back pressure chamber and the tank line By providing a second orifice formed between the front inner peripheral surface and the poppet outer peripheral portion with the pocket ,
Even if the differential pressure of the entire throttle function section is the same as before, the differential pressure across the individual orifices constituting the throttle function section will be small, and the jet velocity from the final stage orifice should be set much lower than before. Can do.
[0019]
Therefore, according to the present invention, the impact sound that the jet flow from the orifice collides with the casing pocket wall portion is suppressed, and as a result, the noise in the hydraulic circuit mother machine is suppressed. The pressure generator of the present invention has the advantage that it can be constructed relatively easily.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a pressure control device for flow control according to the present invention.
2 is a cross-sectional view taken along line AA of the flow rate control pressure generator shown in FIG. 1. FIG.
FIG. 3 is a circuit diagram showing a flow rate control method of a negative control type variable displacement pump hydraulic circuit.
FIG. 4 is a pressure p-flow rate Q characteristic diagram of a flow control pressure generator.
FIG. 5 is a cross-sectional view showing a conventional pressure control device for flow control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Variable capacity pump 10a Pump controller 12 Pump line 14 Actuator 16 Control valve 16a Center bypass passage 20 Signal line 22 Tank line 24 Tank 30 Casing 32 Cap 34 Poppet 36 Front pressure chamber 38 Communication hole 40 Rear pressure chamber 42 (A) Sheet surface (area)
44 Casing pocket 48 (a) Rear pressure receiving part (area)
50 Spring 60 Restriction function portion 60a First (upstream side) orifice 60b Back pressure chamber 60c Second (downstream side) orifice

Claims (2)

Controls the discharge flow rate of the variable displacement pump by introducing the upstream pressure of the pressure generator provided on the outlet side of the center bypass passage of the control valve that supplies the discharge pressure oil of the variable displacement pump to the pump controller of the variable displacement pump. In the pressure generator in the negative control type variable displacement pump hydraulic circuit, the pressure generator is
A poppet having a communication hole that forms a seat surface facing the front pressure chamber formed in the casing into which pressure oil from the control valve is introduced;
A cap having a front and a rear inner peripheral surface that is screwed and fixed to the casing from the opposite side of the front pressure chamber of the casing and slidably supports the outer peripheral surface of the poppet;
A rear pressure chamber for storing a spring for pressing the seat surface toward the casing is formed at the rear portion of the communication hole of the poppet,
A casing communicating with the back pressure chamber formed between the outer peripheral portion of the poppet and the inner peripheral portion of the cap excluding the front and rear inner peripheral surfaces and the back pressure chamber and the tank line. A pressure control device for flow control of a negative control type variable displacement pump hydraulic circuit, wherein a second orifice formed between the front inner peripheral surface and the poppet outer peripheral portion is provided between the pocket and the pocket . 2. The negative control type variable displacement pump hydraulic circuit according to claim 1, wherein the flow passage areas of the first orifice and the second orifice are set to increase sequentially from the upstream side to the downstream side. Pressure control device for flow rate control.

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