JPH0534458B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention provides a method for raising and turning the boom of a hydraulic excavator, and when the actuators connected to each of the hydraulic switching valves belonging to the same hydraulic switching valve group are operated simultaneously, the relative speed of both is determined. Relating to a device that allows for good selection and adjustment.

Conventional technology Conventionally, the hydraulic switching valves in the same hydraulic switching valve group of a hydraulic excavator have a parallel circuit configuration, and in order to distribute the desired amount of pressure oil to each actuator using the switching valve, it is necessary to use hydraulic pressure. The operator was operating while artificially adjusting the amount of movement of the switching valve's spool.

Hereinafter, a conventional embodiment will be described with reference to a hydraulic circuit diagram of a hydraulic excavator shown in FIG. 5, in which the second boom raising speed (described in detail in the embodiment) and swinging are operated simultaneously.

When the boom operation lever 38 in FIG. 5 is operated to tilt the pilot valve 15 to the maximum, the pilot pressure oil reaches the pilot oil chamber of the hydraulic switching valve 9 via the pilot oil passages 30 and 31, and the pilot pressure oil reaches the pilot oil chamber of the hydraulic switching valve 9. At the same time as moving the spool of valve 9 to position D,
Since the extended oil passage of the pilot oil passage 30 also communicates with the pilot oil chamber of the hydraulic switching valve 6, the spool of the hydraulic switching valve 6 is also moved to the D position.

As a result, the oil discharged from the second hydraulic pump 3 is
4. D position passage of hydraulic switching valve 9, oil passages 39, 40
The oil discharged from the first hydraulic pump 2 passes through the oil passage 23, the D position passage of the hydraulic pressure switching valve 6, and the oil passage 41, and joins the oil passage 40 described above. It flows into the boom cylinder 13.

In this state, when the hydraulic switching valve 14 belonging to the same hydraulic switching valve group A as the hydraulic switching valve 6 is switched and its spool position moves to D or E, the pressure oil in the oil passage 23 is also diverted to the oil passage 34, It flows into the swing motor 12 through the D or E position passage of the hydraulic switching valve 14. At this time, the hydraulic switching valves 6 and 14 are both in the oil path 2.
3 are arranged in parallel, a large amount of pressure oil from the first hydraulic pump 2 flows into either the boom cylinder 13 or the swing motor 12, whichever has the lower load pressure.
The actuator is mainly actuated. Therefore, in order to make the relationship between the boom rising speed and the swinging speed favorable, the load pressure characteristics of the boom cylinder 13 and the swing motor 12 are calculated in advance at the time of circuit design, and the characteristics of the load pressure of the boom cylinder 13 and the swing motor 12 are calculated in advance, and The hydraulic circuit is configured taking into account the work conditions, but this is only effective when using standard attachments to perform standard work under standard work conditions, and moreover, in general. This causes a decrease in circuit efficiency.

For example, when the front attachment of a standard machine equipped with a standard backhoe attachment is replaced with a special clam shell with a large weight as shown in Figure 3, it is natural that the boom cylinder 1
The steady load pressure applied to the first hydraulic pump 2 increases, and when the above-mentioned boom raising and swinging operations are performed simultaneously, most of the pressure oil in the first hydraulic pump 2 flows only into the swing motor 12.

Furthermore, Fig. 4 is a diagram showing the relationship between the boom rising height H and the swinging development angle θ when the bucket 49 is loaded with work objects and is moved to the transport vehicle Tx or Ty by simultaneously raising and swinging the boom. The shortest distance to move the work object to the transport vehicle Tx or Ty from the excavation end point O as the origin is to rotate the workpiece while raising the boom, and the travel trajectory of the bucket 49 must be a straight line X or Y. Finally, when the boom rising height Hx, the turning angle θx,
Alternatively, work efficiency will not improve unless Hy and θy respectively, but as is clear from the figure, in order for the movement locus of the bucket 49 to become straight lines x and y, the boom must rise for the same turning angle θx. The height is on the straight line X or Hx, and on the straight line Y it is H'y
Therefore, for the same boom rising height Hy, the required angle for turning is θy on straight line Y, but θ'y on straight line X is sufficient.

When two of the actuators connected to the hydraulic switching valves arranged in parallel in the same hydraulic switching valve group as described above are operated at the same time, one of them is operated preferentially at a certain ratio. JP-A-Sho is a publication regarding the prior art to ensure that turning is given priority when the arm and turning of a power shovel are operated simultaneously.
It is disclosed in Publication No. 60-5928.

This technology aims to ensure flow to the swing side when the swing and arm are operated simultaneously.By switching the swing priority switching valve using the pilot pressure of the swing operation part, the switching valve for the swing and arm can be operated under the same conditions. Among the pressure oil pipelines of the hydraulic power source that were supplied in parallel under the ).

However, such conventional technology alone cannot handle the usage situations mentioned above, for example, when a front attachment of a hydraulic excavator is installed with a different total weight than the standard product, or when the working conditions are various. It was impossible to deal with this problem, and we had to rely on the skill of the driver.

Problem to be Solved by the Invention During actual work, the weight of the workpiece added to the bucket 49 does not change significantly as the work is repeated, but it varies depending on the work conditions, the location of the work equipment,
For example, the placement conditions of transport vehicles Tx and Ty are diverse,
With conventional machines, in order for the transport vehicle to handle this,
Thanks to long-term experience and intuition, the control lever for raising the boom,
The aim was to improve efficiency by delicately adjusting the swing control levers, but this was distracting and dangerous. In addition, in order to improve the relative speed of the boom raising and turning, the oil passage 34 or 41 shown in Fig. 5 has been made into a fixed throttle oil passage as necessary in the conventional machine. For example, there may be a decrease in circuit efficiency when operating independently, or there may be a deficiency in handling the usage conditions.

In the present invention, even when the boom is raised and swung at the same time as described above, even an inexperienced operator can easily obtain the relative speed between the two that is most suitable for the working conditions. Moreover, it is an attempt to realize a hydraulic circuit that does not reduce efficiency during independent operation.

Means for Solving the Problem A normally open passage is formed in the pressure oil inflow passage to the hydraulic switching valve for an actuator with low load pressure, or the oil passage leading from the hydraulic switching valve to the actuator. A variable throttle valve is provided that exerts a throttling effect in proportion to the pressure signal acting on the part, and the receiving part of the throttle valve is opened only when the actuator is operated in the direction where the load pressure increases. Connect the outlet port of the pressure reducing valve through a switching valve, whose pressure can be adjusted arbitrarily.

Function When performing work that involves operating an actuator with a high load pressure and an actuator with a low load pressure at the same time, set the outlet port pressure of the pressure reducing valve to a value that suits the work conditions at that time in advance. When the hydraulic pressure switching valve is operated, the switching valve installed in the oil passage leading to the receiving part of the variable throttle valve opens.
The pressure signal regulated by the pressure reducing valve acts on the receiving part of the variable throttle valve and exerts a throttling effect proportional to the pressure signal, so the amount of oil flowing into the actuator with low load pressure is limited and the remaining oil is Pressure oil flows into the other actuator at a higher pressure,
Moreover, this inflow amount can be arbitrarily set by adjusting the pressure reducing valve.

In addition, when the hydraulic switching valve for the actuator on the side with higher load pressure is not operated, the switching valve is closed, so the variable throttle valve installed in the oil passage for the actuator on the side with lower load pressure forms a normal open passage. Therefore, no special circuit resistance is applied.

Embodiments Examples of the present invention will be described with reference to the drawings.

FIG. 1 shows a hydraulic circuit diagram partially omitted when the present invention is applied to a hydraulic excavator of a hydraulic remote control type. 1 is a first hydraulic pump 2;
The engine drives the second hydraulic pump 3 and the pilot pump 4. The first hydraulic pump 2 sucks oil from the tank 21 through the suction strainer 19.
The discharge oil is pressure regulated by the relief valve 18 and passes through the oil passage 23 to the hydraulic switching valve 7 for left travel and the second boom lifter.
The first switching valve group A consists of a hydraulic switching valve 6 for speed, a hydraulic switching valve 5 for arm first speed, a hydraulic switching valve 14 for swing motor 12, etc., and the output of the second hydraulic pump 3 is The pressure is regulated by the relief valve 20 and passes through the oil path 24. Hydraulic pressure switching valve 8 for right travel, hydraulic switching valve 9 for boom raising and lowering 1st speed, hydraulic switching valve 10 for bucket, hydraulic pressure for arm 2nd speed. Switching valve 1
1 forms a second switching valve group B.

The hydraulic switching valves belonging to the first and second switching valve groups A and B form a parallel hydraulic circuit for each group, and when each hydraulic switching valve is in a neutral position, that is, when not operated, the hydraulic switching valves are in a Although the oil passage is closed, the pressure oil sent through the oil passage 23 or 24 passes through the internal neutral bypass oil passage, enters the oil passages 35 and 36, respectively, and enters the merging oil passage 2.
5, oil cooler 26, return filter 2
7 and return to tank 21.

Also, a pilot oil passage 30 connected to the pilot pressure outlet port of the pilot valve 15 operated by the operating lever 38 and its branch pilot oil passage 3
1 communicates with the pilot oil chamber that moves the spools of the hydraulic switching valves 6 and 9 to the side where the boom cylinder 13 extends, and a pilot oil passage 33 connected to the pilot pressure outlet port of the pilot valve 15' connects the spools of the hydraulic switching valves 6 and 9 to the side where the boom cylinder 13 extends. The spool is connected to a pilot oil chamber in which the boom cylinder 13 is moved to the contracting side, and further, the pilot oil passage 30 branches to form an actuator oil passage 47. Reference numeral 16 denotes a variable throttle valve, which controls the oil passage 34 from the oil passage 23 to the hydraulic switching valve 14 that supplies pressure oil to the swing motor 12. Under normal conditions, the internal passage is fully open, and when a hydraulic signal is applied to the receiving section, the oil passage 34 is closed. It has a function of changing the throttling effect of the internal passage in proportion to the magnitude of the signal, and a pilot oil passage 32 communicates with the pilot oil chamber. Other hydraulic switching valves, etc., i.e., the first switching valve group A
Hydraulic switching valves 5, 8, check valve 17 belonging to the second switching valve group B, and hydraulic switching valves 8, 10, belonging to the second switching valve group B.
11 and the like are similar to switching valves in conventional hydraulic excavators, and are operated by hydraulic signals from respective dedicated pilot valves (not shown).
The pressure oil of the second hydraulic pump 3 is switched and supplied to each actuator to operate it.

The oil discharged from the pilot pump 4 serves as a pilot hydraulic pressure source for the hydraulic switching valves 5, 6, 7, 8, 9, 10, 11, 14 and the throttle valve 16.
The discharged oil passes through a line filter 28, is pressure regulated by a relief valve 22, and is supplied through an oil passage 29 to pilot valves 15, 15', an electromagnetic proportional pressure reducing valve 45, etc., which will be described later. Further, 37 is a brake valve for protecting the motor circuit when starting and stopping the swing motor 12.

Further, 46 is a variable current switch, which is an external signal means usually installed near the driver's seat, and can output an electrical signal of any size.This output circuit is connected to the receiving part of the electromagnetic proportional pressure reducing valve 45. There is.

The electromagnetic proportional pressure reducing valve 45 converts the pressure oil discharged from the pilot pump 4 into a pressure signal proportional to the magnitude of the electric signal input to the receiving section, and transmits the pressure oil through the pilot oil line 48 connected to its outlet port. This is connected to the inlet port of the hydraulic switching valve 44.

The switching valve 44 normally shuts off the pilot oil passage 48 and communicates the pilot oil passage 32 with the tank 21, but when a pressure signal is applied via the aforementioned pilot oil passage 47 leading to the receiver, it switches and The oil passages 48 and 32 communicate with each other, and the tank port has a function of being shut off. The oil passage and the like constitute an adjusting device that arbitrarily changes and sets the throttling effect of the variable throttle valve 16 as necessary.

Next, the operation in the above hydraulic circuit will be explained.

First, a description will be given of the case where the boom cylinder 13 is operated solely by extending and contracting. Generally, a large load is applied to the boom of a hydraulic excavator, which requires a great force and a high operating speed when ascending. The oil is supplied to the oil chamber, and when descending, the oil discharged from one hydraulic pump is guided to the contraction side oil chamber. When the operating lever 38 in FIG. 1 is operated to the boom upward side, the pilot pressure oil of the pilot valve 15 passes through the pilot oil passages 30 and 31 and acts on the pilot oil chamber of the hydraulic switching valve 9, changing the spool position to the C position. Since the boom is moved from the D position to the D position, the pressure oil in the oil passage 24 flows into the extension side oil chamber of the boom cylinder 13 through the D position passage of the hydraulic switching valve 9 and the oil passages 39 and 40, and when the boom is raised. At the same time, since the pilot oil passage 30 also communicates with the pilot oil chamber of the hydraulic switching valve 6, an attempt is made to switch the spool of the switching valve 6 from the C position to the D position. When the pilot pressure is relatively low in order to use the extension speed differently between 1st speed and 2nd speed, the spool on the hydraulic switching valve 9 side moves in advance, and when the pilot pressure further increases, the spool position of the hydraulic switching valve 9 changes. Since the spool of the hydraulic switching valve 6 is moved to the D position while remaining in the D position, the operating lever 38 must be fully operated to send a higher pilot pressure signal from the pilot valve 15 to the oil passage 30. In this case, the hydraulic switching valve 6 does not operate. When the spool of the switching valve 6 moves to the D position due to the high pilot pressure signal, the pressure oil from the oil passage 23 passes through the D position passage of the switching valve 6, the oil passage 41, and the pressure oil backflows from the oil passage 39. Push open the check valve 17 for prevention, and open the oil passage 3.
9, and passes through the oil passage 40 to the boom cylinder 1.
It flows into the extension side oil chamber of No.3. Therefore, only the pressure oil from the second hydraulic pump 3 enters the extension side oil chamber of the boom cylinder 13 at the initial stage of operation of the operation lever 38, and only the pressure oil from the first hydraulic pump 2 and the second hydraulic pump 3 enters the extension side oil chamber at the later stage of operation. Pressure oil merges and flows in.

Next, the operation lever 38 is operated in the opposite direction, and the pressure of the pilot pressure oil from the pilot oil passage 33 connected to the pilot pressure outlet port of the pilot valve 15' increases, and the pilot pressure on the contraction side of the boom cylinder 13 of the hydraulic switching valve increases. When the oil flows into the oil chamber, the spool of the hydraulic switching valve 9 moves to the E position, and the oil passage 2
The pressure oil 4 is in the E position passage of the hydraulic switching valve 9, oil passage 4.
2 and 43, and flows into the small side oil chamber of the boom cylinder 13 to lower the boom.

Next, a case will be described in which the swing motor 12 is operated independently.

When the swing operation lever is operated and the spool of the hydraulic switching valve 14 is switched to the D or E position in response to a pressure signal from the pilot valve (both not shown) linked to this, the oil flow from the branched oil passage of the oil passage 23 is The pressure oil passes through the fully open passage of the variable throttle valve 16 without any resistance, passes through the oil passage 34, and then reaches the hydraulic switching valve 14.
The hydraulic motor 12 is rotated forward or reverse through the D or E position passage under the protection of the brake valve 37. Therefore, when the swing motor 12 is operated independently, the entire amount of oil discharged from the first hydraulic pump 2 flows into the swing motor 12.

Next, in the hydraulic excavator with the hydraulic circuit shown in Fig. 1, the boom lift operation is performed when a large load is constantly applied to the boom cylinder 13 as shown in Fig. 3, or when the swing operation angle is small as shown in Fig. 4. A case will be explained in which it is necessary to obtain a large amount of power, and the turning operation and the boom raising operation are performed at the same time.

In order to raise the boom, when the operating lever 38 is fully tilted and high pilot pressure from the pilot valve 15 flows into the pilot oil passage 30, the spools of the hydraulic switching valves 9 and 6 both move to the D position as described above. , the pressure oil of the first pump 2 and the second pump 3 both try to flow into the boom cylinder 13, but if the operating levers for operating the swing motor are operated at the same time, the spool of the hydraulic switching valve 14 also moves to D or E.
Since the pressure oil of the first pump 2 is moved to the position, the pressure oil of the first pump 2 should be dispersed and flowed in inverse proportion to the load pressure of the actuator connected to each of the hydraulic switching valves 6 and 14. However, in the present invention, the circuit diagram As shown in the figure, a pilot oil passage 47 branches from the pilot oil passage 30.
The pilot pressure signal acts on the receiving part of the switching valve 44, and the valve 44 is switched, so that the pilot oil passages 32 and 48 are communicated with the electromagnetic proportional valve 45, variable current switch 46, etc. that constitute the control device. A preset pressure signal acts on the receiving part of the variable throttle valve 16 and exerts a predetermined throttle effect, so that the hydraulic switching valve 1 passes from the branched oil passage of the oil passage 23 through the oil passage 34.
4 is throttled by the variable throttle valve 16 and subjected to passage resistance, so that the pressure oil in the first hydraulic pump 2 maintains the hydraulic pressure even when a high load is applied to the boom cylinder 13. An appropriate amount of pressure oil is distributed to the switching valve 6. In this way, the value of the pressure signal applied to the receiving part of the variable throttle valve 16 is adjusted by the adjustment device, and the pressure signal value is adjusted in advance according to the load pressure applied to the boom cylinder 13 and the required swing angle suitable for the working conditions. By setting this in advance, a good relative speed can be obtained without making fine adjustments to the operating lever even during work that involves simultaneous operations.

FIG. 2 is a hydraulic circuit diagram showing a second embodiment of the present invention. In the first embodiment, even when the load pressure of the boom cylinder 13 is higher than that of the swing motor 12 at the time of initial operation, it is still smaller than the swing angle. When the boom tends to rise insufficiently, the amount of pressure oil flowing into the swing hydraulic switching valve 14 is limited by the variable throttle valve 16, whereas in the second embodiment, the initial resistance of the swing is The position of the variable throttle valve 16 has been changed in order to apply it to work conditions where the swing speed is insufficient compared to the rising speed of the boom. That is, the variable throttle valve 16 is connected to the oil passage 4.
The outlet port of the shuttle valve 50, which takes out the pressure signal of the pilot oil passage for operating the hydraulic switching valve 14, is connected to the receiving part of the switching valve 44 through the pilot oil passage 47'. The structure is the same as that of the first embodiment, and the operation is the same as described above in that a variable throttling effect is applied to the actuator circuit of the actuator with a low load pressure.

As in the embodiment, when the variable throttle valve 16 and its adjustment device are used, when the work content changes in one hydraulic excavator and there are many changes in the load applied to the actuator, such as when raising the boom, the swing speed can be adjusted depending on the work conditions. The variable current switch 46
It is possible to easily respond by adjusting. In this embodiment, the variable current switch 46 and the electromagnetic proportional pressure reducing valve 45 were used to adjust the variable throttle valve 16, but instead of this, a manual proportional pressure reducing valve or other means may be used to adjust the variable throttle valve. Even so, the object of the present invention can be achieved.

Effects of the Invention In the hydraulic excavator having the hydraulic and electric circuits according to the present invention, the hydraulic switching valves that are in the same hydraulic switching valve group and arranged in parallel circuits, such as the boom and swing, can be operated simultaneously. and
When performing a predetermined combined operation, the throttle of the variable throttle valve 16 may be adjusted in advance, even if changes in the operating method are required due to changes in the load due to the workpiece or front attachment, or changes in work conditions. By setting the adjustment device that changes the effect to suit the load and working conditions at that time, a predetermined relative speed can be obtained without the need to delicately operate the operating lever as in the past, increasing work efficiency. It also makes it easy for beginners to perform complex driving operations.

[Brief explanation of the drawing]

Figures 1 and 2 are hydraulic circuit diagrams and partial electrical circuit diagrams showing the first and second embodiments of the present invention, respectively, and Figure 3 is a hydraulic excavator equipped with a special clam shell as a front attachment. FIG. 4 is a diagram showing the relationship between boom lift height and swing angle of a hydraulic excavator, and FIG. 5 is an example diagram of a hydraulic circuit in a conventional hydraulic excavator. 12...Swivel motor, 13...Boom cylinder, 15, 15'...Pilot valve, 16...Variable throttle valve, 44...Switching valve, 45...Solenoid proportional pressure reducing valve, 46...Variable current switch, 50 ...Shuttle valve, A, B...Hydraulic switching valve group.

Claims (1)

[Claims] 1. A hydraulic switching valve of a hydraulic switching valve group consisting of a plurality of parallel circuit type hydraulic switching valves operated by a pilot pressure signal acting on a receiving section is switched to transfer pressure oil to fronts with different load pressures. In a hydraulic circuit that distributes to various actuators for attachments, it is installed in the pressure oil supply oil path to the actuator with low load pressure in the same switching valve group, and the throttling effect is proportional to the pressure signal acting on the receiving part. A variable throttle valve that changes, a pressure reducing valve that communicates with a pilot oil pressure source oil line and that can adjust the pressure at an outlet port according to a signal value from the outside, and an external signal means that supplies a signal to a receiving section of the pressure reducing valve. , is located in the middle of the oil passage leading from the outlet port of the pressure reducing valve to the receiving part of the variable throttle valve, and normally the oil passage leading to the receiving part of the variable throttle valve is communicated with the tank, but there is no load on the receiving part. Only when a pilot pressure signal is applied to switch the actuator switching valve in the direction where the pressure increases, the oil passage leading to the receiving part of the variable throttle valve is shut off from the oil passage leading to the tank and communicated with the outlet port of the pressure reducing valve. 1. A device for varying the relative speed of an actuator of a hydraulic excavator, comprising: a switching valve for controlling the relative speed of an actuator. 2. A pilot device according to claim 1, which extracts as a signal the pressure of any one of a plurality of connecting oil passages connecting an actuator with a high load pressure and its hydraulic switching valve to a receiving part of the switching valve. A device for varying the relative speed of an actuator of a hydraulic excavator, characterized in that the device uses a pressure signal means.