JPS6182009A - Controller of counterbalance valve - Google Patents

Abstract

PURPOSE:To prevent creation of a hunting or the like by detecting displacement of the lever of a change-over valve and adjusting traveling speed of a controller of a controlling spool on the basis of the displacement of the lever. CONSTITUTION:A displacement signal (x) of the lever 40 of a change-over valve is sent to a traveling speed operating part 41, which computes a traveling speed of a hydraulic actuator S. The obtained speed signal is sent to a target opening operating part 42, which computes a target opening of the controller of a controlling spool. The obtained target opening signal is sent to a target travel operating part 43, which computes the target travel of the controlling spool. Consequently, based on displacement of the lever of the change-over valve, the opening of the controller of the controlling spool can be adjusted and controlled discarding pressure at the side of a supply passage, that is generated at the application time of a counter load. Generation of a hunting can therefore be prevented if pressure at the side of the supply passage is fluctuated remarkably.

Description

Detailed Description of the Invention (Field of Industrial Application) This R[ is a control grJ system for a counterbalance valve used in a load moving device such as a power shovel or winch, which prevents the load from running away. This was prevented.

(Prior art) Figure m5 shows a control circuit of a conventional device, in which a rod side chamber l of a cylinder S for raising and lowering a load W is connected to a switching valve V via a passage 2.
On the other hand, the bottom side chamber 3 is connected to the switching valve V via one passage 4. 'And, a counterbalance valve C is connected to the passage 4, and this counterbalance valve C has a control valve section 5 and a check valve section 6 as two elements.

The control valve section 5 is provided with a pilot chamber 5a, and the pilot chamber 5a is communicated with the passage 2 via a damp pig orifice 5b. The control valve section 5 normally maintains a closed state due to the action of a spring 7 provided on the opposite side of the pyroft chamber 5a, but the pilot pressure acting on the pyrotechnic chamber 5a is set at a set pressure. When the pressure exceeds that level, the opening degree is controlled according to the pilot pressure.

Also, the check valve section 6 is! , +7 The structure is such that only the flow of oil from the switching valve V to the bottom private chamber 3 is allowed.

When the switching valve V is switched to the right position in the figure, the oil discharged from the pump P is supplied to the bottom side chamber 3 via the passage 4 and the check valve section 6, and the oil in the rod side chamber 1 is supplied to the tank T. Since it returns, the shilling S operates to increase the load W.

Also, if the switching valve V is switched to the left side in the drawing.

The oil discharged from the pump P is supplied to the rod side chamber 1, and the pressure within this passage 2 acts as pilot pressure on the pilot chamber 5a via the damping orifice 5b.

When this pilot pressure becomes equal to or higher than the set pressure, the control valve section 5 opens and the oil in the bottom side chamber 3 is drained from the tank T.
Therefore, Schilling S operates to lower the load W. When the control valve section 5 opens in this way, the load W decreases, and the rate of descent at that time is proportional to the degree of opening of the control valve section 5.

Eventually, depending on the magnitude ξ of the pilot pressure, the control valve portion 5
The opening degree of the bottom chamber 3 is controlled, and the return flow rate from the bottom chamber 3 is regulated to prevent the load from running on its own.

(Problems to be Solved by the Invention) In this conventional device, the pilot pressure is guided from the 1 passage 2 side to control the opening degree of the #I W * section 5, so there is a problem that a hunting phenomenon occurs. For example, when the control valve section 5 is opened using the above pilot pressure, the load W suddenly drops at that moment, and the oil supply to the rod side chamber L cannot follow this, and therefore the passage 2 side As the pressure on the 0 passage 2 side decreases, the biloft pressure decreases, and at that moment the control valve section 5 performs a valve closing action.

By repeating such a valve opening action and a valve closing action, hunting occurs in the control valve part 5, but the more the control valve part reacts to changes in viroft pressure, the more the load increases. The larger W becomes, the more severe the hunting becomes.

Therefore, if the opening activity of the damping orifice 5b is made smaller and the responsiveness of the control valve section 5 to changes in pilot pressure is worsened, hunting can be prevented to some extent, but if the damping orifice 5b is made smaller, there If the orifice 5b becomes clogged with debris, the valve function will be impaired, so there is a limit to how small the orifice 5b can be, and for this reason, the hunting phenomenon described above cannot be completely prevented. There was a problem.

In other words, this conventional counterbalance valve employs a control method that makes the pressure on the supply passage 2 side, that is, the pilot pressure PI, equal to the clarification pressure Per of the control valve section 5. 5 can only be controlled indirectly.

Moreover, since the pressure fluctuation of the pilot pressure P1 is very large, I
The opening degree of the I control valve portion 5 becomes more likely to fluctuate.

Therefore, hunting cannot be prevented unless the damping orifice 5b is made very small, but there is a limit to making the damping orifice 5b small as described above. could not prevent this.

An object of the present invention is to provide a control device that prevents hunting by adjusting the opening degree of the counterbalance valve regardless of the pressure on the supply passage side when a counterload is applied. .

(Means for Solving the Problems) In order to achieve the above object, the present invention adjusts the opening degree of the control section according to the amount of movement of the control spool, and
In a counterbalance valve control device that prevents load escape by controlling the flow rate on the return side when a counter load is applied by adjusting the opening degree of this control section, the control spool is connected to the input N of the electric actuator. , the amount of movement of the hydraulic actuator is controlled in accordance with an electric signal, and the movement speed of the hydraulic actuator is calculated by H based on the lever displacement when the switching valve is switched in a situation where the counter load is applied. A speed calculation section and a target flow rate signal obtained by multiplying the speed signal output from this movement speed calculation section by the pressure receiving area of the hydraulic actuator on the side that becomes high pressure when a counter load acts are input, and this target flow rate signal is calculated. A target opening calculation unit calculates the target opening of the control spool control unit based on the target opening calculation unit, and a target movement amount of the control spool is calculated based on the 1 probe degree signal output from the target opening calculation unit. A target movement amount calculation unit that calculates the target movement amount, and a movement speed signal calculated by multiplying the target movement amount signal output from the target movement amount calculation unit by a coefficient are input, and this movement speed signal is integrated to calculate the movement of the control spool. The control spool is provided with an integral circuit for calculating the amount of movement, and is configured to input the amount of movement of the control spool as an electric signal to the electric actuator.

(Operation of the present invention) As described above, the displacement of the switching valve lever can be detected and the opening degree of the control portion of the control spool can be adjusted based on the lever displacement.

(Effects of the present invention) This invention adjusts the opening degree of the control section of the control spool to Since control is possible, hunting can be prevented even if the pressure on the supply passage side fluctuates drastically.

Furthermore, since the damping orifice is controlled in a 71Z-like manner, there is no need for a damping orifice as in the prior art, and therefore there is no need for management that takes into account clogging of the damping orifice.

(Embodiment of the present invention) The first section is a circuit diagram of the present invention, and the second section is a counterbalance valve that is FT-driven by an exciting current to a proportional solenoid, and a rod side chamber of a cylinder S that raises and lowers a load W. 10 is connected to the switching valve V via a passage 11, while a passage 13 is connected to the bottom side chamber 12, a counterbalance valve C is connected to this passage 13, and a main body 15 of this counterbalance valve C is connected to the switching valve V via a passage 11. 1st ~
4 boats form 18-IS.

And 5. On the first day of the first boat, the boat passed through 5 passages 20.
The second port 17 is connected to the switching valve V, and the second port 17 is connected to the passage 13.
The third port 18 is connected to the tank T. Zarani, 4th Po) 19.

(Pilot) Connected to pump PP.

A valve hole 21 is roughly formed in this main body 15, and one end of this valve hole 21 is closed with a closing member 22, while the other end is provided with a stroke amount of a push rod 23a according to an excitation current that is an input electric signal. A proportional solenoid 23 is provided as a controlling '9% actuator.

In addition to the proportional solenoid, a servo motor, a stepping motor, etc. can be considered as the electric actuator, and a voltage other than current may be used as an input signal to the electric actuator.

A control spool C5 is installed in the valve hole 21, and a pilot spool PS is slidably installed in the control spool C5. A spring 25 is interposed between the control spool C8 and a spring receiver 24 provided on the closing member 22 side.

Normally, the action of this spring 25 brings it into contact with the end surface of a spacer 26 provided in F:i contact with the electric actuator 23.

Furthermore, the above-mentioned piecoattos boule PS has a spring receiver 24.
A spring 27 is interposed between the rod portion 24a and the tip end surface of the rod portion 24a, and normally this pyro/toss boule PS comes into contact with a step portion 26a formed on the inner diameter of the spacer 26.

The bushing rod 23a of the proportional solenoid 23 acts on the tip of the pyro/) spool PS, that is, the end opposite to the spring 27, but the specific configuration of both spools PS and C5 is as follows. It is as follows.

That is, the control spool C5 is connected to the first boat 1.
A control portion 29 that forms a first annular recess 28 corresponding to ε and tapers toward the first annular recess 28 side.
is formed. When the control spool C3 moves against the spring 25, the control section 29 functions according to the movement position, and the first port hll (and the second boat 17
The degree of opening when communicating with the valve is controlled.

In addition to the first annular recess 28, a second annular recess 30
, while forming the third annular recess 31, the spacer 28
An annular passage 32 is formed that is open to a pilot chamber 33 on the side.

The 'i:B2 annular recess 30 always communicates with the third port 18 regardless of the movement position of the control spool C5, and also communicates with the control spool C8 through the hole 33 formed at the bottom of the annular recess 30. It communicates with the hollow part 34.

Further, the t53 annular concave concave portion 1 is also connected to the control spool C5.
The pilot spool PS always communicates with the fourth port 19 regardless of the moving position of the pilot spool PS, but the hole 35 formed at the bottom of the annular recess 31 opens and closes depending on the moving position of the pilot spool PS. That is, when both spools cs and ps are in the normal position shown in the figure, the hole 35 is covered by the pilot spool PS, but the spool spool PS is closed by the pilot spool PS.
Is it spring 2? When the pilot spool PS moves against this, the hole 35 and the annular ring 36 formed in the pilot spool PS communicate with each other.

Further, the annular passage 32 is connected to the annular #l! via a hole 37 formed in the control spool C5. I have a relationship where I always M'A to 3B.

When the proportional solenoid 23 is excited, the bush loft 23a is stroked in response to the input electric signal, and the pilot spool PS is moved against the spring 27 in accordance with the stroke amount.

When the pilot spool PS moves in this way, the third
Since the annular recess 31 and the annular groove 36 communicate with each other, the pyro
/) Pressure oil from Bonda PP is transferred to the 4th boat 19-3rd
It flows into the biloft chamber 38 via the annular recess 31 - hole 35 - annular 36 -> hole 37 -> annular passage 32, and its pressure acts on the end face of the control spool C5.

When this pilot pressure acts, the control spool C5 moves against the spring 25 and stops at a position where the 1M control spool C5 hole 35 is blocked by the pyro and toss spool Ps. In this way, depending on where the control spool C5 stops, the ff1l bottle 1st and the 2nd port [7
The opening degree of the proportional solenoid 23 is determined, which is ultimately proportional to the input electric signal of the proportional solenoid 23. Also, encouragement Fa 7;,! When R decreases, the pilot spool Ps is moved by the spring 27.
It remains until the position where it balances with the reaction force of Pi O, To chamber 3
9 Force No. M communicates with M through hole 3B, so oil in pilot chamber 39 flows from communication hole 38 to pilot spool PS to hollow part 4
0 - hole 33 of control spool C5 - annular groove 30 -> short circuit to tank T via third boat 18.

In other words, the control spool C5 moves # following the pilot spool PS, and the control spool C5 catches up with the pilot spool PS and both spools c
, ps maintain the illustrated relative relationship, the control spool C5 stops, so the amount of movement of the control spool C5 is proportional to the amount of movement vJ of the pilot spool PS. The amount of movement of this pilot spool PS is
As mentioned above, the stroke of the bush loft 23a is proportional to the stroke of the bush loft 23a, but since the stroke of the bush loft 23a is proportional to the input electric signal of the proportional solenoid 23, the movement of the control spool C3 is proportional to the stroke of the bush loft 23a. The zero amount will be proportional to the input electrical signal of the proportional solenoid 23.

Now, if the switching valve V is switched from the neutral position shown in the figure to the left position, and the input electric signal of the proportional solenoid 23 is maximized to maximize the opening degree in the control section 23, then
A state of free flow occurs between the first boat 1G and the second boat 17.

Therefore, the oil discharged from the pump P passes through the first passage 20 -> the first boat 16 -> the first annular recess 28 -> the fully open control part 29 - the second port 17 - 4 and the operating check valve 14 to the bottom toilet compartment 12. Along with being supplied, the rod side chamber 1
Since the zero oil returns to the tank via the passage 11, the load W increases.

At the same time as switching the switching valve V to the left position in the drawing.

The proportional solenoid 23 is energized, and the control section 29
If the opening degree is determined, the return oil from the bottom side chamber 12 will return to the tank T according to the opening degree.

The load W decreases.

The descending speed of the load W is determined according to the opening degree of the control section 29, and the opening degree is controlled by the input electric signal of the proportional solenoid 23.

The electrical circuit shown in FIG. 1 controls the input electrical signal for determining the opening degree of the control section 29.

This circuit is provided with a moving speed calculating section 41 to which the displacement signal X of 8-40 when switching the switching valve V to the left side position in the figure is input. Based on this, the moving speed of the cylinder S is calculated. In other words, the opening degree of the switching valve V is determined according to the displacement of the lever 40, and the supply flow rate to the cylinder at that time is also determined.
can be determined as a function of the amount of displacement. Therefore, when the displacement signal X of 8-40 is inputted to the calculation section 41, the moving speed of the cylinder S is calculated based on it and the speed signal V is output.

The target control flow rate page is calculated by multiplying the speed signal V output from the calculation unit 41 by the pressure receiving surface A2 of the bottom side chamber 12 of the cylinder S, and the target flow rate signal Q is sent to the target opening calculation unit 42. input.

In addition to the above-mentioned target flow rate signal, the pressure signal P2 of the bottom side chamber 12 is input to the target opening degree @ military part 42.

Both of these signals are possible, and based on P2, the control spool C3
The target opening degree a of the control unit 23 is τ=ζ/2 ρ
Find it by

The target opening degree signal τ obtained in this manner is input to the target displacement calculation section 43. Since the target opening degree of the control section 29 is taken as 11xll of the displacement of the control spool C5, the target displacement calculating section 43 calculates the target movement amount y based on the target opening degree i. calculate.

The movement speed y of the control spool C5 is calculated by multiplying the target movement amount y obtained in this way by the coefficient β, and this movement speed t is integrated by the integrating circuit 44 to determine the movement of the control spool CS. l] Find the quantity y.

Movement My of control spool C8 calculated as above
is input as the TrL signal i to the proportional solenoid 23 of the counterbalance valve C via the amplifier 45 to control the control spool C5.

Further, in the circuit shown in FIG. 1, the movement MY is fed back and compared with the target movement amount i.

/Help movement speed? =(y-y)β, and integrates this valve movement speed again to form a stability compensation circuit that calculates the pulp displacement y.

Therefore, when the switching valve vt-t is repositioned to the left in the drawing, the discharge oil from the pump P connected to the carrot E is supplied to the rod side chamber 10 of the cylinder S, and the hydraulic oil in the bottom side chamber 12 is , returns to tank T via counterbalance valve C.

At this time, depending on the displacement of the lever 40 of the switching valve V,
The amount of displacement of the control spool C8 of the counterbalance valve C is controlled as described above, and the opening degree of the control section 2B is also substantially adjusted, so even if a counter load acts on the cylinder S, it will not be affected. I don't have any worries about running away.

Second fruit 1 shown in Figure 3! ! In this example, a detection unit 46 is provided to detect the rotation speed of the carrot E, and the coefficient α obtained from the rotation signal N of the engine E and the function (f) is determined using the detection unit 46.

The coefficient α obtained in this manner is input to the secondary displacement calculation unit 47, and the secondary displacement calculation unit 47 multiplies the lever displacement X by the coefficient α to obtain the secondary displacement X′.
This secondary displacement X' is input to the moving speed @3i section 41.

Based on this secondary displacement X', the movement amount y of the control spool C5 is determined in the same manner as in the first embodiment.

That is, this second actual journey example differs from the first embodiment in that the moving speed calculating section 41 calculates the moving speed V of the cylinder S according to the rotational speed of the engine E.

Therefore, in the case of the first embodiment, when the rotational speed of the engine E is at the maximum, the moving speed V of the cylinder S can be determined in the entire displacement range of the lever 40. When the rotation speed of the carrot is below the maximum rotation speed, the pump discharge amount also differs depending on the rotation speed, so the correlation between the displacement X of the lever 40 and the moving speed of the cylinder S changes. And the engine E
When the rotation speed is low, such as idling, lever 4
Even if 0 is displaced, a region is created in which the moving speed of the cylinder does not change.

However, in this force 2 actual journey example, the rotation speed N of the engine E is taken into consideration to the lever displacement X, and the moving speed V of the cylinder at the maximum lever displacement , the above-mentioned moving speed vt over the entire range of lever displacement X can be calculated.

In this second embodiment, the comparison circuit is provided for four days. This comparison circuit 48 includes a pressure receiving area A of the rod side chamber lO of the cylinder S, and a pressure receiving area A2 of the bottom side chamber 12.
In addition, the lever displacement signal X, the pressure P1 of the loft side chamber IO and the bottom side chamber 12 are
The pressure P2 is inputted.

When the lever displacement signal X is input, the comparison circuit 48 is activated and compares which of P, XA, and P2XA2 is larger.

Then, when PIAl<P2 A2, in other words, when a counter load acts on the cylinder S, the comparison circuit outputs 12 signals from the 4th to the solenoid valve 4.
9 to lower the set pressure of the relief valve 50.

Since the set pressure of the relief valve 50 can be lowered in this way,
Pressure effects unrelated to the counter load can be reduced, thereby preventing hunting and reducing energy loss.

In addition, when the load is reversed during the operation of the cylinder S and the load is subsequently controlled by the counterbalance valve C,
The supply pressure on the first passage 11 side is maintained at high pressure until the load is reversed, but after the load is reversed, the circuit pressure is controlled to a low pressure by the T-drop leaf valve 50. .

The third embodiment shown in Figure 44 is the one in which a free fall prevention circuit 51 is added to the second actual journey example.

In other words, this free fall prevention circuit 51 operates when the lever 40 that should change the switching valve V to the left position 2 +A is operated, and the pressure Pl in the rod side chamber 10 and the cracking pressure Per of the relief valve 50 are P, When the condition ≦Pcr is met (2), that is, when the load is in a free fall condition, the comparator cp operates to switch the switching unit 52. Switching section 52
is switched, the difference between the pressure P in the loft side chamber 10 and the cracking pressure Pcr (PI-Pcr) is multiplied by a coefficient α, the moving speed y of the control spool C5 is reduced, and the opening area of the control section 29 is To further reduce the size, electric signals to the proportional solenoid are controlled.

[Brief explanation of the drawing]

Figure 51 is a circuit diagram of the first embodiment, Figure 2 is a sectional view of the counterbalance valve, Figure 3 is a circuit diagram of the second actual journey, Figure 4 is a circuit diagram of the third embodiment, and Figure 4 is a circuit diagram of the third embodiment. FIG. 5 is a conventional circuit diagram. S... Cylinder as a hydraulic actuator, ■...
Switching valve, C...Counter balance valve, 23...Proportional solenoid as electric actuator, C5...Control spool, 28...Control unit, 40...-Lever, 4
1.--Movement speed calculation section, 42-.Target opening degree calculation section, 4
3...Target movement amount wave π section, 44...Integrator circuit.

Claims (1)

[Claims] The opening degree of the control section is adjusted according to the amount of movement of the control spool, and by adjusting the opening degree of this control section, the flow rate on the return side is controlled when a counter load is applied, preventing load escape. In the control device for the counterbalance valve, the control spool has a configuration in which the amount of movement thereof is controlled according to the input electric signal of the electric actuator, and the amount of movement of the control spool is controlled in accordance with the input electric signal of the electric actuator. A movement speed calculation section that calculates the movement speed of the hydraulic actuator based on the lever displacement, and a pressure receiving area of the hydraulic actuator on the side that becomes high pressure when a counter load acts on the speed signal output from this movement speed calculation section. A target opening calculation unit inputs the target flow rate signal obtained by multiplying by A target movement amount calculation unit that calculates the target movement amount of the control spool based on the target opening degree signal, and a movement speed signal that is calculated by multiplying the target movement amount signal output from the target movement amount calculation unit by a coefficient. and an integrating circuit that calculates the amount of movement of the control spool by integrating the movement speed signal, and inputs the amount of movement of the control spool as an electric signal to the electric actuator. Control device.