JPS60139902A - Drive unit of flashing valve - Google Patents

Abstract

PURPOSE:To achieve smooth actuation of a titled device used in a hydraulic closed circuit having a single rod cylinder, by selecting a main line having a smaller pressure from the main line on the rod side or the main line on the head side for connection with the tank line. CONSTITUTION:A solenoid operated type flashing valve 15 which is controlled by a control device 20 is used in a hydraulic closed circuit which has an arrangement connecting a variable capacity hydraulic pump 1 to a single rod cylinder 2 via a main line on the rod side (A) and a main line on the head side (B) and is provided with a crossover relife valve 3 and the flashing valve 15 between the main lines (A, B). Information such as the operating direction (X) of an operational lever 17, the moving direction (Y) of the cylinder 2 and pressures Pa, Pb of the each main line (A, B) are input to the control unit 20. When the operating direction (X) and the moving direction (Y) coincide, the flashing valve is controlled so that the main line having the smaller pressure selected from the main lines (A, B) is connected to the tank line (C).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device for a flushing valve used in a hydraulic closed circuit equipped with a variable displacement hydraulic pump and a single rod cylinder.

In a hydraulic closed circuit equipped with a single-rod cylinder as an actuator, a flushing valve is connected between the rod-side main pipe and the head-side main pipe, and this flushing valve relieves the low-pressure side main pipe of the double-sided pipes. Means of connection to the tank via a valve has been adopted. Such a hydraulic closed circuit will be explained with reference to a diagram.

FIG. 1 is a circuit diagram of a hydraulic closed circuit using a conventional flushing valve. In the figure, 1 is a variable displacement hydraulic pump equipped with a variable displacement mechanism 1a, and 2 is a single rod cylinder connected to the variable displacement hydraulic pump l. The variable displacement hydraulic pump 1 and the single rod cylinder 2 are connected by a rod main line A and a head side main line B. 3 is a crossover relief valve connected between main pipes A and B. 4 is a flushing valve connected between the main pipes A and B, which introduces the pressure of the bidirectional pipes A and H into the pilot boat and is driven by the differential pressure therebetween. That is, when the differential pressure is small, the flushing valve 4 does not operate and maintains the neutral position 4b, but when the pressure in the main pipe A becomes higher than the pressure in the main pipe 'B by more than a set value, the flushing valve 4 switches to the position 4a. On the other hand, when the pressure in the main pipe B increases, the 7 lashing valve 4 is switched to the position 4c. 5 is a hydraulic oil tank, and 6 is a relief valve provided between the flushing valve 4 and the tank 5. C
is from the flushing valve 4 to the tank 5 via the relief valve 6.
Shows the conduit leading to. 7a and 7b are pipe C and both pipes A and B
Check valve 8 provided in between is pipe C1 check valve 7
a or the check valve 7b to drain the oil from the tank 5 into the main pipe A.
, B.

In such a hydraulic closed circuit, when the pressure in the main line B becomes higher than the pressure in the main line by more than a set value, the flushing valve 4 is switched to position 4C, and the main line on the low pressure side switches to the line C.
The main conduit B is cut off from the conduit C and is closed. When the oil in the main pipe A on the low pressure side becomes surplus, this oil flows into the pipe C, and the pressure exceeds the set pressure of the relief valve 6! JIJ-7 valve 6 opens, and excess oil is returned to tank 5 via flushing valve 4 and line C1 relief valve 6. □When there is a shortage of oil in the main conduit A of low EEO III, the charge pump 8 is activated to supply oil from the tank 5 to the main conduit line via the conduit C1 check valve 7a.

By the way, now, a small force F (a force equivalent to j@friction force of the single-rod cylinder 2) is being applied from the outside to the rod of the single-rod cylinder 2 in the direction of contracting the rod as shown by the arrow, and the rod side and Let's assume a situation where main pipe B has a slightly higher pressure than main pipe A due to the difference in the pressure receiving area on the head side.

In this case, the pressure in main pipe B is Pb, and the pressure in main pipe A is P
If a is Pb ) Pa , the flushing valve 4 is switched to position 4C, the main pipe line is connected to the pipe C, and the main pipe B is cut off from the pipe C.

In this state, the displacement volume is variable 'a'! 1tla
Operate the variable displacement hydraulic pump l on one side p Rad cylinder 2
When the rod is driven in the direction of contraction, the oil in the main line B is caused to flow into the main line A by the variable displacement hydraulic pump 1. However, as mentioned above, the force F is extremely small, so even if the oil in the main pipe B flows into the main pipe A, the single rod cylinder 2 does not move. This is because, although some of the oil that has flowed into main pipe A from main pipe B flows into single-rod cylinder 2, other oil flows out into tank 5 through flushing valve 4 and relief valve 6. Yes, and the flow rate is small. Therefore, the pressure in the main pipe A does not exceed the set pressure of the relief valve 6, and the single rod cylinder 2 cannot be moved with this pressure.

As a result, if a small force F is applied to the single rod cylinder 20 in the direction of retracting it, even if you try to drive the single rod cylinder 2 in the direction of retracting the rod by operating the variable yt pump 1, the single rod cylinder 20 will not work. This causes the inconvenience that 2 cannot be moved. and,
If the single-rod cylinder 2 is, for example, an arm cylinder with a hydraulic blind pel, and such a closed hydraulic circuit is adopted in the arm system hydraulic circuit, a small force is applied from the outside in the direction of retracting the rod of the arm cylinder. This is a condition that occurs during actual operation of a hydraulic excavator, and in this case, there is a risk that the hydraulic excavator will be unable to perform its work, and the above-mentioned inconvenience becomes an extremely serious defect.

The present invention has been made in consideration of these circumstances, and its purpose is to solve the above-mentioned conventional problems and to provide a seven-piece latching valve that can drive a single-rod cylinder without any trouble in any condition. to provide driving equipment.

,.

In order to achieve this object, the present invention detects the operating direction of an operating device such as an operating lever for operating a single-rod cylinder and the actual moving direction of the single-rod cylinder, and determines whether or not these two directions match. The comparison means compares the two cylinders, and when they match, a predetermined signal is generated. On the other hand, the pressure in the main pipe connected to the rod side of the single-rod cylinder and the pressure in the main pipe connected to the head side are detected. The forces applied to the head side and the rod side obtained by the pressure are compared by other comparison means, and when the predetermined signal is generated, the main pipe on the side with the smaller force is connected to the tank pipe. The % sign indicates that the valve is driven.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 2 is a system diagram of a flushing valve driving device according to an embodiment of the present invention. In the figure, the same parts as those shown in FIG. 1 are given the same reference numerals. 15 is a flushing valve used in this embodiment, and is connected to main pipes A, B and pipe CK.

This flushing valve 15 has an electromagnetic solenoid 15d11.
5e, and when both magnetic solenoids 15d and 15e are not energized, the flushing valve 15 is in the neutral position 15.
When the electromagnetic solenoid 15d is energized, the flushing valve 15 is switched to position 15a to shut off the amphibious pipes A and B and pipe C. When the solenoid 15e is connected and the electromagnetic solenoid 15e is energized, the flushing valve 15 is switched to the position 15C to connect the main conduit A and the conduit C.

Reference numeral 16 denotes an IJ valve connected to the main pipe A, and its set pressure is selected to be higher than the set pressure of the IJ valve 6 in the pipe C. Reference numeral 17 denotes an operating lever for operating the variable displacement TrNk'#41at of the variable displacement hydraulic pump l. The operating lever 17 is equipped with a device (for example, a potentiometer) that outputs an electric signal (operating signal) X corresponding to the operating direction and amount of the operating lever.

Reference numeral 18 denotes a length measuring device provided on the single rod cylinder 2, which outputs an electric signal (displacement signal) Yt- corresponding to the direction and displacement position of the single rod cylinder 20. 19a, 19b
is a pressure detector that detects the pressure P of the main pipe line and the pressure Pb of the main pipe H, and outputs an electric signal (pressure signal) corresponding to the pressure Pa1Pb, respectively. Input the operation signal X, displacement signal Y and each pressure signal Pa, Pb,
This control device outputs a drive signal id%ie to the electromagnetic solenoids 15d and 15e of the flushing valve 15 based on these values. The details of the configuration of the control device M2D are shown in FIG.

FIG. 3 is a block diagram of the control device shown in FIG. 2. In the figure, 21 is a differentiator that inputs the displacement signal Y, differentiates it, and outputs a speed signal. n, edict, tame, and 5 are each comparators. The comparator n has a set speed value Δ, compares the speed signal Y with the set value Δ, and outputs a high level signal H when the speed signal Y is equal to or higher than the set value 28. In this case, the set value Δ is the set value in the direction in which the rod of the single rod cylinder 2 extends. Comparator n has a speed setting value Δ, inputs the speed signal Y, and outputs a high level signal H't- when the speed signal Y is less than or equal to the set value Δ. Set value Δ1 is the set value in the direction in which the rod cylinder 20 rod contracts. The comparator inputs the operation signal X, and if the signal X is positive (X>O),
That is, when the operating lever 17 is operated in the direction of extending the rod of the single rod cylinder 2, a high level signal H is output. The comparator 5 inputs the operation signal X, and the signal X is negative (
When X<O), that is, when the operating lever 17 is operated in the direction of retracting the rod of the single-rod cylinder 2, a high level signal H is output. The base is a comparator, which inputs the output signal of Sae, and an AND element that outputs a high level H when both signals are high level H, and the valley inputs the output signal of comparison Masuda, 5,
AN that outputs high level H when both signals are high level H
I) It is an element.

29, the pressure signal P is added at a preset amplification degree, respectively.
The amplifier 31 that amplifies a1Pb is an adder that calculates the difference between the output signal of the amplification container and the output signal of the amplifier (9). The adder 31 outputs a difference signal f. Here, if the amplification degree of the amplification vessel is set to a value proportional to the pressure receiving area Ar on the rod side of the single rod cylinder 2, the output signal of the amplifier 29 will be proportional to the rod side force Pa・Ar applied to the single rod cylinder 2. It is a proportional value, and the amplifier (material)
If the degree of amplification is set to a value proportional to the pressure-receiving area Ab on the head side of the single-rod cylinder 2, the output signal of the amplifier will be equal to the force Pb on the head side [force Pb
The value is proportional to fist Ab. Therefore, the difference signal f output from the adder 31 is a value proportional to the difference between the forces on the rod side and the head side of the single rod cylinder 2, that is, foe
Pb @ Ab −Pa ・Ar. 32 is a comparator that inputs the difference signal f, and f is 0 or positive (f≧0).
In other words, when the force in the direction of extending the rod in the single-rod cylinder 2 is large, a high level H is output. 3
3 is a comparator that inputs the difference signal f, and f is negative (f(
0), that is, when the force in the direction of contracting the rod in the one-piece rod cylinder 2 is large, a high level H is produced.

34 is an AND element which inputs the output signal of the ON element and the output signal of the comparator 32, and outputs a high level signal when both signals are at high level H. It is an AND element that inputs an output signal and outputs a high level signal when both signals are at high level H.A.3
7 is an amplifier that amplifies the high level signal when the ANL) element 35 outputs a high level signal, and each amplifier 36
．． The outputs of 37 are electromagnetic solenoids 15e and 15d, respectively.
added to.

Next, the operation of this embodiment will be explained. Now, a small force F is applied to the single rod cylinder 2 in the direction of retracting the rod, the pressure in the main pipe B is slightly higher than the pressure in the main pipe A, and the operating lever 17 is in the neutral position. think of. In this state, the force applied to the head side of the one-rod cylinder 2 is larger, so the difference signal f becomes positive, and the output signal of the comparator 32 is at a high level.The output signal of the H1 comparator is at a low level. It is L. Further, since the operating lever 17 is in the neutral position, the operating signal X becomes 0, and the output signals of the comparators 24 and 25 both become low level L. Further, since the single-rod cylinder 2 does not move, the a-wave signal Y becomes 0, and the output signals of the comparators 22 and 23 both become low level L. As a result, the output of the 0) (element array becomes low level B/I/L, and the output of the ANI) element array also becomes the low level L, and the 11Km solenoids 15d and 15e
are not energized, and the flushing valve 15 remains in the neutral position 15b.

From this state, when the operating lever 17 is operated to drive the variable displacement hydraulic pump 1 and the single rod cylinder 2 is operated in the direction in which its rod contracts, the operating signal X becomes a negative value (X(0)), and the comparator 5 The output signal becomes high level H. On the other hand,
The oil in the main pipe B is discharged into the main pipe A by driving the variable displacement hydraulic pump l. In this case, the flushing valve 15 is in the neutral position 156, so the flow path from the main pipe A to the pipe C is blocked, and therefore the pressure p of the main pipe RIB is
b decreases, and the pressure Pg in the main pipe increases. and,
When the force applied to the rod side of the single rod cylinder 2 (the sum of the force due to the force F and the pressure Pa) becomes larger than the force applied to the head side, the single rod cylinder 2 starts driving in the direction in which the rod contracts. During this period, if there is a shortage of oil in the main pipe B, oil is supplied from the charge pump 8 via the check valve 7b and pipe C, and if there is excess oil in the main pipe, the excess oil is supplied via the relief valve 16. Released valley. However, the oil is released from the relief valve 16 only for a very short time until the single rod cylinder 2 starts to drive.

That is, when the single-rod cylinder 2 starts driving and the absolute value of its speed signal Y exceeds the absolute value of the set value Δ, the output signal of the comparator 1 becomes high level H. At this time, since the output signal of the comparator section is also at high level H, the output signal of ANI) element n is at high level H, and the output signal of the OR element array is also at high level H.

On the other hand, the force applied to the rod side of single rod cylinder 2 is force F
is extremely small, and is almost equal to the force due to pressure Pa, so it is larger than the force on the head side, and the difference signal f is negative (f<0
), and the output signal of the comparator 33 is at a high level H.

Therefore, the inputs of the element ANf) are both at a high level H, and a high level signal is output from the element ANi), driving the electromagnetic solenoid 15d. As a result, 7
The lashing valve 15 is switched to position 15a, and the main line B is connected to the line C. This state is the same as an open circuit, and the release of oil from the relief valve 16 is instantaneous, and from now on, the drive of the rod cylinder 2 is controlled by the operation lever 17.
According to the amount of operation, it will perform as desired by the operator.

Next, consider a case where the force F applied in the direction of contracting the rod of the single-rod cylinder 2 is relatively large. In this case, when the operating lever 17 is operated to retract the rod of the single-rod cylinder 2, the variable displacement hydraulic pump I is driven, and the oil in the main pipe B is driven.

flows into main pipe A. Since the single rod cylinder 2 has a thick oak, it is shrunk in proportion to the amount of oil reduced in the main pipe B. At this time, the speed signal t is ∆.

<0, and a high level signal is output from the comparator. On the other hand, since the operation signal X is negative (X<o), the output signal of the comparator 5 is also still at level H, and therefore
The output signal of the cable element 2-7 and the OR element becomes high level H. Here, the single rod cylinder 2 is being driven in the direction in which its rods are contracting, and the pressure Pb in the main pipe B is increasing, the force applied to the head side is greater than the force applied to the rod side, and the difference signal f is positive. (f)0), and the comparator 32
The output signal becomes high level H. Therefore, the AND element 340 input signals all become high level h, and the AND element 34 outputs a high level signal, which excites the electromagnetic solenoid 15e. As a result, the flushing valve 15 is switched to position 1.5C, the main pipe A and the main pipe C are connected, and the excess oil generated in the main pipe A due to the difference in the pressure receiving area of the single rod cylinder 2 is discharged to the tank 5. The operation of the single-rod cylinder 2 using the operating lever 17 does not pose any hindrance and can be operated as desired by the operator.

Next, consider the case where the single rod cylinder 2 is driven so as to extend the rod while a force F in the direction of contracting the rod is present. In this case, when the operating lever 17 is operated, the oil in the main pipe A flows into the main pipe BK by the drive of the variable capacity 7 pressure pump l, and the force on the head side j due to the pressure Pb in the main pipe B is applied to the rod. The force becomes stronger, the difference signal f becomes positive (f)O), and the single rod cylinder 2 begins to extend. As a result, when the speed signal Y exceeds the set value 31, each output of the comparator 22 becomes a high level H. Also, since the operation signal X is positive (X>0), the ANI) cable 26,
The output signal of the OR element becomes a high level H. Furthermore, since the difference signal f is positive (f>O), the output signal of the comparator 32 (work height level H), the output signal of the AND element becomes high level H, and the electromagnetic solenoid 15
e is excited. As a result, the flushing valve 15 is in position t.
15 c K is switched, the main pipe A and pipe C are connected, the hydraulic circuit becomes an open circuit state, and the single rod cylinder 2 can be operated as desired by the operator.

Note that even if the force F is a force in a direction that extends the rod contrary to the above explanation, the operation is the same, so the explanation will be omitted.

In this way, in this embodiment, the operating signal of the operating lever, the speed signal based on the displacement signal of the single rod cylinder, and the pressure signal of both main pipes are used to detect when the operating direction of the operating lever and the moving direction of the single rod cylinder match. The main pipe on the side where the smaller force is applied to the head side and the rod side of the single-rod cylinder is connected to the tank pipe by a flushing valve. The rod cylinder can be operated at the operator's discretion.

Note that the control device can also be configured using a microcomputer.

As described above, in the present invention, the operating direction of the operating device and the movement of the single rod cylinder are determined based on the output signals of the operating device for operating the single rod cylinder, the movement detecting device of the single rod cylinder, and the pressure detecting devices of both main pipes of the single rod cylinder. When the direction of movement of the single-rod cylinder matches the direction of movement, the main pipe on the side where the smaller force is applied to the head side and the rod side of the single-rod cylinder is connected to the tank pipe by the flushing valve. Even under such conditions, the single rod cylinder can be operated as desired by the operator.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a hydraulic closed circuit using conventional 7 lashing valves, Fig. 2 is a system diagram of a drive device for 7 latching valves according to an embodiment of the present invention, and Fig. 3 is a control shown in Fig. 2. FIG. 2 is a block diagram of the device. l...Variable capacity hydraulic pump, 2...Single rod silling, 15, curved, flushing valve, 15 d
, 15 e... electromagnetic solenoid, 17... opening operation lever, 18... length measuring device, 19a, 19b...
...Pressure detector, hole control device, 21...
...differentiator, 22.23.24.25.32.33 songs...comparator, 26.27.34.35...song AN l)
Element, aggregation... oFL element, 4, 30... amplifier, 31... times adder. Representative Patent Attorney Junji Takeshi (and 1 other person) Figure 1

Claims (1)

[Claims] A flushing valve that selectively connects a rod-side main pipe and a head-side main pipe of a hydraulic closed circuit equipped with a hydraulic pump and a single-rod cylinder to a tank pipe connected to a tank, and the rod-side main pipe. a first pressure detection device that detects the pressure of the main pipe; and a second pressure detection device that detects the pressure of the main pipe.
a pressure detection device, an operation detection device that detects the operating direction of the operating device that drives the one-rod cylinder, a movement detection device that detects the moving direction of the one-rod cylinder, and a value detected by the operating device and the movement. a first comparing means that outputs a predetermined number 4N when the operating direction of the operating device and the moving direction of the single rod cylinder are the same based on a value detected by the detecting device; and the first pressure detecting device a second comparison means for comparing the force applied to the rond side obtained from the value detected by the second pressure detection device with the force applied to the head side obtained from the value detected by the second pressure detection device; the flushing so that when the predetermined signal is output from the comparison means, the main pipe on the side where the smaller force is detected among the forces compared by the second comparison means is connected to the tank pipe; 1. A flushing valve driving device comprising a driving means for driving the valve.