JPH0384204A - Confluence valve device for load sensing type hydraulic circuit - Google Patents

Abstract

PURPOSE:To save the energy of pump driving force by applying each delivery pressure of both variable delivery pumps and the effective differential pressure between the delivery pressure and control pressure opposedly to both sides of a confluence valve. CONSTITUTION:The sum of the delivery pressure PA of a variable delivery pump 10 and the differential pressure P of a control part 24, and the delivery pressure PB of a variable delivery pump 12 are applied to one side of a confluence valve 34 provided between the pressure oil delivery lines 18, 20 of both variable delivery pumps 10, 12. The sum of the delivery pressure PA of the variable delivery pump 10, the delivery pressure PB of the variable delivery pump 12 and the differential pressure P of a control part 26 is applied to the other side of the confluence valve 34. The delivery flow control lines 36, 38 of both variable delivery pumps 10, 12 are further connected through shuttle valves 40, 42 and the confluence valve 34. Accordingly, at the time of supplying the delivery pressure oil of the variable delivery pump on the high pressure load side into an actuator on the low pressure load side, the delivery pressure of the variable delivery pump on the low pressure load side is not needed to be boosted, and therefore the energy of pump driving force can be saved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a load sensing type hydraulic circuit equipped with a pair of variable discharge pumps 1 each capable of operating a plurality of hydraulic actuators. The present invention relates to a merging valve device (hereinafter referred to as a merging valve device for a load-sensing hydraulic circuit), and more specifically, to a merging valve device that can efficiently merge the discharged oils of both variable discharge pumps.

[Conventional technology]

Generally, in this type of load sensing type hydraulic circuit, when the amount of oil supplied to the actuator belonging to one variable discharge pump is insufficient, this actuator can be supplied with the discharge oil of the other variable discharge pump.
The respective pressure oil discharge lines of both variable discharge pumps are connected via a merging means.

FIG. 2 shows such a merging means. In other words, in FIG.
variable discharge pumps 10, 12, and a plurality of actuators At, At... and B, B,... connected to each of these variable discharge pumps 10, 12, respectively.
... (not shown), adjustable throttle valves (not shown) provided in the pressure oil supply lines 14 and 16 of each of these actuators, and a pressure compensation valve (not shown) that controls the differential pressure across the throttle valves. (not shown), and the pressure oil discharge lines 18.20 of both variable discharge pumps 10.12 are connected via a merging valve 22. In addition, both variable discharge pumps 10.12 control the control pressures PAI+PA2'... and P@l+P@1' of the actuators At, At... and L, 82... belonging to the respective ones.
・The discharge flow rate is controlled by the highest control pressure PA, P, respectively. Therefore, both variable discharge pumps 10
, 12 are the control pressures PA', P.

The differential pressures P applied via the control units 24 and 26 are set to the added pressures PA+ΔP and Pa+ΔP, respectively. In other words, the amount of pressure oil supplied to each actuator is controlled via each throttle valve that functions based on the differential pressure P.

In such a configuration, the merging valve 22 has a sum of the discharge pressures of both variable pumps 10.12 ((PA+Δ
P)+(P,+muP)) is the sum of the control pressures of both variable discharge pumps 10.12 (PA 10h ) and the resistance force of the spring 28 on the opposite side (PA+ Ps +
PI) are configured to be applied in opposition to each other.

Therefore, in the load sensing type hydraulic circuit having such a configuration, each actuator At, A2,
. . , at, B2, . and discharge pressure PA + ΔP, P, + ΔP
However, if the discharge flow rate of either variable discharge pump becomes insufficient, the discharge pressure oil of the other variable discharge pump is replenished. That is, for example, it belongs to the second variable discharge pump 12.

The variable throttle in the supply line 16 leading to one of the second actuators B+, B2, etc. is opened sufficiently to the extent that it is not possible to discharge pressure oil that can secure a predetermined differential pressure ΔP (even in a fully discharged state). In this state, the discharge pressure of the second variable discharge pump 12 is P·1ΔP° (ΔP”×ΔP)t, but cannot increase, and therefore the supply flow rate to the actuator B is lower than the required flow rate. In other words, the discharge flow rate of the second variable discharge pump 12 is insufficient, but in this state, the merging valve device 22 is activated and the excess oil discharged from the first variable discharge pump 10 is discharged. It is supplied to the actuator B via the merging valve 22. In this case, when the merging valve 22 is operated, the control pressures PA, P of both variable discharge pumps 10.12 are both equal to the pressure P^+Pl. The control pressure is set to whichever is higher.

[Problem to be solved by the invention]

However, this type of conventional merging valve device for a load sensing type hydraulic circuit has had the following drawbacks.

That is, the operation of the conventional merging valve 22 is such that, as described above, the control pressures PA and P of both the variable discharge pumps 10.12 are set to the control pressure PA.

This is performed after setting the control pressure to the higher one of P. For this reason, for example, when the control pressure pA<p, the second variable discharge pump 1211 from the first variable discharge pump 10 side! ! No problem occurs if pressure oil is supplied to the pump 1, but on the contrary, when the control pressure is PA>PIl, pressure oil is supplied from the first variable discharge pump 10 side to the second variable discharge pump 12 side. is supplied to the second variable discharge pump 12 side after its control pressure P1 has been increased to PA, that is, the discharge pressure has increased from P3 + ΔP to PA + Δ
After the pressure is unnecessarily increased to P, the first variable discharge pump 10
Replenishment from measurements is carried out. Therefore, in the second variable discharge pump 12, driving power is unnecessarily lost as the pressure pH-+PA increases.

As described above, in this type of conventional merging valve device, unnecessary energy loss occurs when replenishing discharge oil between both variable discharge pumps.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a merging valve device that can efficiently merge discharge oil between both variable discharge pumps in a load sensing type hydraulic circuit without causing unnecessary energy loss. be.

[Means to solve the problem]

In order to achieve the above object, a merging valve device for a load sensing type hydraulic circuit according to the present invention includes a pair of variable discharge pumps, a plurality of actuators connected to each of these variable discharge pumps, and each of these actuators. Each of the variable discharge pumps has an adjustable throttle valve provided in each of the pressure oil supply lines and a pressure compensation valve that controls the differential pressure before and after the throttle valve, and each of the variable discharge pumps has a control pressure of the actuator connected to it. A load sensing device comprising a pair of variable discharge pumps whose discharge flow rate is controlled by the highest control pressure of the variable discharge pumps, and whose respective pressure oil discharge lines of the variable discharge pumps are connected via a merging means. In the type hydraulic circuit, the merging means has an effective pressure difference between the discharge pressure of one variable discharge pump and the control pressure for one side opening, and a discharge pressure of the other variable discharge pump for the opposite side. The effective differential pressures between the pressure and the control pressure are applied oppositely, and when these two effective differential pressures are substantially equal, the space between the same pressure oil discharge lines is blocked, and when it occurs, the space between the same pressure oil discharge lines is blocked. It is characterized by having a control hydraulic circuit that communicates between the two in one direction.

[Effect]

Effective differential pressures between the respective discharge pressures and control pressures of both variable discharge pumps are applied to both sides of the merging valve according to the present invention.

That is, the merging valve merges the discharge pressure oils of both variable discharge pumps so that the effective differential pressures of both variable discharge pumps are always substantially equal.

Therefore, when the discharge pressure oil of the variable discharge pump on the high pressure load side is merged with the actuator on the low pressure load side, the merging is performed without increasing the discharge pressure of the variable discharge pump on the low pressure load side.

〔Example〕

Next, an embodiment of a merging valve device for a load sensing type hydraulic circuit according to the present invention will be described in detail below with reference to the accompanying drawings. For convenience of explanation, the same reference numerals are given to the same components as those in the conventional structure shown in FIG. 2, and the explanation thereof will be omitted.

First of all, the configuration of the load sensing type hydraulic circuit according to the present invention is the same as the configuration of the conventional hydraulic circuit shown in FIG. That is, in FIG. 1, the hydraulic circuit of the present invention includes first and second variable discharge pumps 10.12, and a plurality of (in this embodiment, each 2) actuators A+, Ax and 8. , B, and the pressure oil supply line 14 of each of these actuators AI+^2 +Bl +L
．． Adjustable variable throttle valve 30 provided in each of 16
and a pressure compensation valve (also used as a directional switching valve in this embodiment) 3 that controls the differential pressure across the throttle valve 30.
2, and the pressure oil discharge lines 18.20 of both variable discharge pumps 10.12 are connected via a merging valve 34. Note that the arrangement of the throttle valve 30 and the pressure compensation valve 32 may be reversed to that in this embodiment, and the pressure compensation valve 32 may be provided on the downstream side of the throttle valve 30. However, in this case, the pressure compensating valve 32 is connected to the discharge pressure of the variable discharge pump on one side and the maximum load pressure for controlling the spring resistance and the pump discharge flow rate on the opposite side. In such a hydraulic circuit, both variable discharge pumps 10.12 operate at the higher control pressure of the control pressures P A I + P A 2 and PBl+P12 of the actuators AI+^2 and 81.82 belonging to them, respectively. PA, p
, the discharge flow rate is controlled by . Therefore, the discharge pressures of both variable discharge pumps 10.12 are the control pressure PA,
The pressures PA+ΔP and pl are set to Ps plus the differential pressure ΔP applied via the control units 24 and 26, respectively. In other words, each actuator AI, A2.8! , Bx is the differential pressure ΔP
The amount of pressure oil supplied is controlled through each throttle valve 30 which functions as follows.

However, the merging valve 34 according to the present invention has an effective pressure difference (differential pressure) ΔP between the discharge pressure PA and the control pressure PA of the first variable discharge pump 10 on one side of the discharge line 18. , are applied via the discharge flow rate control line 36, and the effective pressure difference (differential pressure) ΔP between the discharge pressure pH+ΔP of the second variable discharge pump 12 and the control pressure P· to the opposite side is applied to the discharge line 20, respectively. , is applied via the discharge flow rate control line 38.

Discharge flow rate control lines 36.38 of both variable discharge pumps 10.12 are connected via shuttle valves 40.42 and merging valves 34.

Next, the operation of the merging valve 34 according to the present invention having such a configuration will be explained. First, actuators AI, A
2 and the total required flow rate of actuators B, , B2 are the same as those of the first and second variable discharge pumps 1, respectively.
If the maximum discharge flow rate is 0.12 or less, as described above, both variable discharge pumps 10.12 have their respective control pressures PA, pl and discharge pressures PA+ΔP, h+
It is driven by ΔP. That is, in this case the same effective differential pressure ΔP is applied on both sides of the merging valve 34, so that the merging valve 34 blocks between the delivery lines 18.20 of the two variable delivery pumps 10.12.

However, from the equilibrium state, the actuator ^1. A
When the throttle valve 30 leading to either the actuator ^1 or A2 is opened until the sum of the flow rates required for the first variable discharge pump 10 becomes greater than or equal to the maximum discharge flow rate of the first variable discharge pump 10, the first
Even if the variable discharge pump 10 performs maximum discharge with respect to its control pressure PA, the discharge pressure is PA0mP.

(ΔP°<ΔP), that is, the discharge flow rate of the first variable discharge pump 10 can only increase up to ΔP°<ΔP. This results in a state where the total required flow rate of ^2 is insufficient. However, in this case, the merging valve 34 has
On one side thereof, there is an effective differential pressure ΔP of the first variable discharge pump 10.
On the side opposite to ° is the effective differential pressure Δ of the second variable discharge pump 12.
P is applied, so the merging valve 34 is switched to the valve position 34A, that is, a position where pressure oil can be supplied from the discharge line 20 of the second variable discharge pump 12 to the discharge line 18 of the first variable discharge pump 10. . Note that in this state, both discharge flow rate control lines 36. ．． 3g are communicated via shuttle valves 40 and 42.

Therefore, the second variable discharge pump 1 in the above state
Discharge oil replenishment from the second opening to the first variable discharge gang 10 side is performed without changing the control pressures PA and P when the control pressure is PA < Ps, and the control pressure is PA
> Ps, the control pressure is increased to the control pressure PA.

As described above, according to the merging valve device according to the present invention, when replenishing the discharge pressure oil of the variable discharge pump on the high pressure load side to the actuator on the low pressure load side, the replenishment is performed by the variable discharge pump on the low pressure load side. This can be done without increasing the discharge pressure. Therefore, in the above-mentioned replenishment, compared to the conventional merging valve device that increases the discharge pressure of the variable discharge pump on the low-pressure load side to the discharge pressure of the variable discharge pump on the high-pressure load side, it is possible to achieve energy savings in the driving power of the pump 6. I can do that.

Although the present invention has been described above with reference to preferred embodiments, the present invention can be modified in many ways within the scope of its spirit.

〔Effect of the invention〕

As explained above, the merging valve device for the load sensing type hydraulic circuit according to the present invention has the effective differential pressure between the discharge pressure and the control pressure of both variable discharge pumps facing each other on both sides of the merging valve. As a result, when replenishing the discharge pressure oil of the variable discharge pump on the high pressure load side to the actuator on the low pressure load side, the replenishment can be performed without increasing the discharge pressure of the variable discharge pump on the low pressure load side. Therefore, in the above-mentioned replenishment, the pump driving force is reduced compared to a conventional merging valve device in which the discharge pressure of the variable discharge pump on the low pressure load side is increased to the discharge pressure of the variable discharge pump on the high pressure load side. Energy saving can be achieved.

4,

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram illustrating a merging valve device for a load sensing type hydraulic circuit according to the present invention, and FIG. 2 is a hydraulic circuit diagram illustrating a merging valve device for a conventional load sensing type hydraulic circuit. 10...First variable discharge pump 12...Second variable discharge pump 14.16...Supply line 18.20...Discharge line 24.26...Control unit 30...Variable throttle Valve 32...Pressure compensation valve 34...Merge valve 36.38...Discharge flow rate #J control line 0, 42...
・Shuttle valve At, A2 +Bl, B2...actuator P
A, P11... Control pressure ΔP... Effective differential pressure FIG.

Claims (1)

[Claims] (1) A pair of variable discharge pumps, a plurality of actuators connected to each of these variable discharge pumps, adjustable throttle valves provided in the pressure oil supply lines of each of these actuators, and a difference before and after the throttle valves. and a pressure compensation valve for controlling the pressure, and each of the variable discharge pumps has its discharge flow rate controlled by the highest control pressure of the control pressures of the actuators connected to each variable discharge pump. In a load-sensing hydraulic circuit equipped with a pair of variable discharge pumps in which the pressure oil discharge lines of the respective pressure oil discharge lines are connected via a merging means, the merging means connects one variable discharge pump to the other. An effective pressure difference between the discharge pressure and the control pressure is applied to the opposite side, and an effective pressure difference between the discharge pressure of the other variable discharge pump and the control pressure is applied to the opposite side, respectively, and both of them are applied. A load sensing device characterized by having a control hydraulic circuit in which the effective differential pressures are approximately equal, and when the two pressure oil discharge lines are blocked, and when they are different, the two pressure oil discharge lines are communicated in one direction. type hydraulic circuit merging valve device.