JPH05195561A - Hydraulic shock-absorption controller for construction equipment - Google Patents

Abstract

PURPOSE:To protect a detector detecting the relative distance between a boom and a cylinder from soil and sand, etc., by installing the detector to the web of the boom of the shock absorption controller 10 for a boom derricking cylinder and controlling a direction changeover valve on the basis of a detecting signal when the cylinder reaches near the stroke end of the cylinder. CONSTITUTION:The relative distance of a boom 3 and a cylinder 4 is brought near when a boom cylinder 4 is further elongated and brought near to a stroke end, a preset distance is detected by a proximity switch 32 when the relative distance reaches the preset distance, the detecting signal is transmitted over a changeover valve through a wiring 33, and the changeover valve is changed over to a close position. Since the proximity switch 32 is positioned within the width of the rod of the boom 3 and surrounded by brackets 3a, 3b mounted to the boom 3, it is protected from an obstruction such as soil and sand, rock, etc. The proximity switch 32 detecting the distance of the boom 3 and the boom cylinder 4 and a control means 43 controlling the driving speed of the boom cylinder 4 are separated, and the control means 43 is installed onto the upper revolving superstructure 2 of a hydraulic shovel, thus preventing abutting against soil and sand, rock, etc., during working.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber control device for a hydraulic cylinder such as a boom cylinder mounted on a construction machine such as a hydraulic excavator.

[0002]

2. Description of the Related Art A construction machine such as a hydraulic excavator in the related art will be described with reference to FIG.

FIG. 8 is an overall view of a hydraulic excavator. In the figure, 1 is an undercarriage, 2 is an upper revolving structure as a working machine body that is provided on the lower traveling structure so as to be rotatable, and has a power source. The boom 4 attached has one end attached to the upper revolving structure 2 and the other end attached to the boom 3, and the boom cylinder 5 has one end rotatably attached to the other end of the boom 3. An arm cylinder 6 having one end attached to the boom 3 and the other end attached to the arm 5, 7 a bucket rotatably attached to the other end of the arm 5, and 8 an end portion. A bucket cylinder is attached to the arm 5 and the other end is attached to the bucket 7. The operation of the boom 3, the arm 5, and the bucket 7 is performed by expanding and contracting the boom cylinder 4, the arm cylinder 6, and the bucket cylinder 8.

During the work of the hydraulic excavator, the boom cylinder 4, the arm cylinder 6 and the bucket cylinder 8
Is often driven to the end of the stroke. In that case, a piston (not shown) of the cylinder collides with the cylinder case to generate an impact, and the impact increases as the driving speed increases. For example, as a lot of work performed by a hydraulic excavator, a loading work is performed in which the boom 3 is raised while turning the upper revolving structure 2 at the same time, and the excavated earth and sand is carried to the loading platform position of a transport vehicle such as a truck and dumped. is there. When performing this work, in order to match the swing speed of the upper swing body 2, the operator operates the boom operation lever (not shown) to the maximum speed position to raise the boom 3 at high speed. At this time, the relationship between the displacement of the stroke amount of the boom cylinder 4 and the swing angular velocity of the boom 3 is as shown in FIGS. 9 to 11. FIG. 9 is a diagram showing the movement amount of the boom 3 with respect to the extension of the boom cylinder 4 in the vicinity of the stroke end of the boom cylinder 4, and FIG. 10 is the boom cylinder 4 when the stroke amount of the boom cylinder 4 is medium.
It is a figure showing the amount of movement of boom 3 with respect to the extension of. Here, the extension amount of the boom cylinder 4 is the same in FIGS. 9 and 10. FIG. 11 is a graph showing the relationship between the displacement of the stroke of the boom cylinder 4 and the angular velocity of the boom. According to the figure, when the stroke amount of the boom cylinder 4 is medium, the angular velocity of the boom 3 is minimum with respect to the displacement amount of the boom cylinder, and when the stroke amount is large, the angular velocity of the boom 3 with respect to the displacement amount of the cylinder is also large. For this reason, the boom 3 near the stroke end of the boom cylinder 4 is driven at high speed, and the impact when the boom 3 is stopped at the stroke end becomes extremely large. As a result, the boom cylinder 4 is damaged or its impact is propagated to the entire hydraulic excavator, which causes the durability of hydraulic equipment and the structure constituting the hydraulic excavator to be reduced, and the hydraulic excavator sways. This made the operator feel uncomfortable.

In order to solve such a problem, a conventional hydraulic shock absorber control device disclosed in Japanese Utility Model Laid-Open No. 56-150256 has been considered. This content will be described with reference to FIGS. The same components as those in FIG. 8 described above are designated by the same reference numerals, and the description thereof will be omitted.

In FIGS. 12 and 13, reference numeral 9 denotes a conduit for supplying pressure oil to the head side oil chamber of the boom cylinder 4 (not shown) when the boom cylinder 4 extends, and 10 denotes the rod chamber side oil chamber of the boom cylinder 4. This is a conduit for guiding the pressure oil of (1) to a tank (not shown). Reference numeral 11 denotes a variable throttle valve which is interposed in the pipe line 9 and is attached to the boom 3 as a buffer control device. As shown in FIG. 14, the variable throttle valve 11 includes a valve case 11a, which is the main body of the valve, and the valve case 11
A swingable spool 11b contained in a, an operation tool 11c as a means for detecting the distance between the boom 3 and the boom cylinder 4 attached to one end of the spool 11b, and the spool 11b that does not limit the flow rate It is composed of a spring 11d that is pressed to the side position.

In the hydraulic shock absorber control device configured as described above, the boom cylinder 4 is extended to raise the boom 3, and the boom 3 approaches the stroke end as shown in FIG. The space between the boom cylinder 4 and the boom 3 becomes narrower, and the boom cylinder 4 contacts the operating tool 11c of the variable throttle valve 11 attached to the boom 3. As a result, when the operating tool 11c is pushed into the valve case 11a, the spool 11b is also switched to the throttle position, the flow rate of the pressure oil supplied to the head side oil chamber of the boom cylinder 4 is limited, and the boom 3 is raised. In the vicinity of the stroke end, the drive speed of the boom cylinder 4 becomes slow, so the impact at the stroke end of the boom cylinder 4 is reduced.

As the boom 3 is lowered, as shown in FIG. 12, the space between the boom cylinder 4 and the boom 3 is widened, the operating tool 11c of the boom cylinder 4 is separated, and the operating tool 11c is moved by the spring 11d. As the push-out operation is performed, the spool 11b is switched from the throttle position to a position where the flow rate is not restricted. That is, in the most part of the stroke of the boom 3, the boom cylinder 4 is driven at a speed according to the operation amount of the operation lever, so that the boom 3 is quickly moved up and down.

As described above, the variable throttle valve provided near the rod of the boom cylinder 4 for detecting the distance of the boom cylinder 4 to the boom 3 is directly ON-OFF detected near the stroke end of the boom cylinder 4. Since the structure is possible, the structure is simple as a whole.

[0010]

However, in the above-mentioned conventional structure, since the variable throttle valve as the buffer control device is interposed in the circuit of the boom cylinder which is hydraulically driven, the variable throttle valve is A structure that can withstand the driving pressure is required, resulting in a large size. As a result, there are many parts protruding from the boom, which may come into contact with earth and sand or rocks during work such as excavation, resulting in damage.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a hydraulic shock absorber control device for construction equipment capable of preventing contact with earth and sand, rocks and the like during work.

[0012]

In order to solve the above-mentioned problems, the feature of the structure adopted by the present invention is that the working machine main body and one end of the working machine main body are rotatable as shown in the above claim 1. A boom connected to the boom, a boom cylinder for raising and lowering the boom, a direction switching valve for controlling expansion / contraction drive of the boom cylinder, and a first valve provided on one side of the direction switching valve.
Pilot chamber and a second pilot chamber provided on the other side, a first pilot valve and a second pilot valve for operating the directional control valve, and a tank connected to the first and second pilot valves. And a pressure oil source, a first pilot line connecting the first pilot valve and the first pilot chamber, and a second pilot line connecting the second pilot valve and the second pilot chamber. In the provided construction machine, the detection means for detecting the relative distance between the boom and the boom cylinder is formed within the width of the rod of the boom cylinder,
The detecting means is attached to the abdominal surface of the boom near the rod end of the boom cylinder, and the pressure limiting means provided on the working machine body is provided on at least one side of the first and second pilot conduits. , Of the second pilot room,
The control is performed so that the pressure on the side where the pressure limiting means is provided decreases.

Further, as described in claim 2, a working machine main body,
A boom whose one end is rotatably connected to the work machine body,
Construction equipped with a directional control valve that supplies pressure oil discharged from the hydraulic pump to the head-side oil chamber or rod-side oil chamber of the boom cylinder and guides the return pressure oil from the head-side oil chamber or rod-side oil chamber to the tank. In the machine, the detection means for detecting the relative distance between the boom and the boom cylinder is formed within the width of the rod of the boom cylinder, and the detection means is attached to the belly face of the boom near the rod end of the boom cylinder. The work machine main body is provided with a flow rate limiting means for limiting the flow rate of the pressure oil supplied from the hydraulic pump to the boom cylinder so as to reduce the boom drive speed.

According to the above-mentioned claim 1 or 2, a pair of left and right brackets for connecting the boom cylinders are fixed to the abdominal surface of the boom, and the detecting means is attached to the boom within the pair of bracket widths. is there.

In the above-mentioned claim 1 or 2, the detecting means is a contact type switch. In the above-mentioned claim 1 or claim 2, the detection means is a non-contact type switch.

[0016]

When the first pilot valve is operated, the pressure oil from the pressure oil source passes through the first pilot pipe line and enters the first pilot chamber of the directional control valve. When supplied, the directional control valve is switched to the switching position on one side, the boom cylinder is driven, and the boom is raised and lowered. When the boom cylinder is driven and reaches the vicinity of the stroke end, the detecting means detects a preset value of the relative distance between the boom and the boom cylinder, and the detection signal is provided in the first or second pilot conduit. To the pressure limiting means. The pressure limiting means controls the pressure of the pressure oil supplied to the first pilot chamber to a preset pressure by the detection signal, adjusts the switching amount of the directional control valve, and is supplied to the boom cylinder. The boom cylinder drive speed is controlled to be slow by limiting the flow rate of the pressure oil.

According to the second aspect of the invention, when the boom cylinder is driven and reaches the vicinity of the stroke end, when the flow rate limiting means is provided in the pipeline for supplying the pressure oil to the boom cylinder, the boom is detected by the detecting means. The relative distance between the boom cylinder and the boom cylinder detects a preset value, and the detection signal is transmitted to the flow rate limiting means. The flow rate limiting means limits the flow rate of the pressure oil supplied to the boom cylinder to a preset flow rate by the detection signal, and the drive speed of the boom cylinder is controlled to be slow.

Here, since the detecting means is formed within the width of the rod of the boom cylinder and is arranged on the abdominal surface of the boom in the above-mentioned claim 1 and claim 2, the rod protects from obstacles such as earth and sand and the like during work. To be done.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention is shown in FIGS.
I will explain based on. The same components as those shown in FIGS. 8 to 14 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, 20 is a main hydraulic pump, 23 is a directional valve that is interposed between the boom cylinder 4 and the main hydraulic pump 20, and controls the supply of pressure oil to the boom cylinder 4, and 23a and 23b are directional valves. First and second pilot chambers respectively provided on both sides of the switching valve 23, 22 is a pipe connecting the main hydraulic pump 20 and the pump port P of the directional switching valve 23, and 21 is pressure oil in the pipe 22. Of the maximum pressure of the relief valve 37, the first and second pilot valves 34,
An operating means composed of 35, which outputs a pressure corresponding to the operation amount of the operating lever 36, 38 a pilot hydraulic pump which is a pressure oil source for operating the direction switching valve 23, 40
Is operating means 37 for operating the pressure oil discharged from the hydraulic pump 38.
To the first pilot chamber 2 of the first pilot valve 34 and the directional control valve 23, and 39 is a relief valve for defining the maximum pressure of the pressure oil in the pipe 40.
3a is connected to a first pilot line, 28 is a second pilot line connecting the second pilot valve 35 and the second pilot chamber 23b of the directional control valve 23, and 44 is a line shown in FIGS. As shown in FIG. 2, a two-position switching valve 31 having an open position d and a closed position e provided on the upper swing body 2 and interposed in the first pilot conduit 27, and the switching valve 31 in parallel with the switching valve 31. The directional control valve 23 is connected to the bypass line 29 connected.
Of the pressure oil supplied to the pilot chamber 23a of the first pilot chamber 2
It is a pressure limiting means composed of a check valve 43 which allows only the flow of pressure oil returning from 3a to the tank 41.
Further, reference numeral 32 is a proximity switch as a detecting means for detecting the distance between the boom 3 and the boom cylinder 4, which is O
N-OFF operation is performed, and the proximity switch 32 turns the boom 3
Is formed within the width of the rod of the boom cylinder 4 in the width direction. A pair of left and right brackets 3a and 3b for supporting the rod side of the boom cylinder 4 are provided on the belly surface of the boom 3. The proximity switch 32
Is attached to the boom 3 between the brackets 3a and 3b so as to fit within the width of the boom cylinder rod as shown in FIG. Reference numeral 33 is a wiring as a transmission means for transmitting the detected signal to the switching valve 31, and is arranged on the side surface of the boom 3.

In the hydraulic shock absorber control device constructed as described above, when the operating lever 36 is operated in the direction of the arrow a in the figure, the pressure oil discharged from the hydraulic pump 38 is generated by the operating means 3.
7 to the pilot line 27. The pressure oil supplied to the pilot conduit 27 passes through the switching valve 31 and is supplied to the pilot chamber 23a of the direction switching valve 23, and the direction switching valve 23 is switched to the left position in the figure. Thereby,
The pressure oil discharged from the main hydraulic pump 20 is the directional switching valve 2
The oil is supplied to the head-side oil chamber 4a of the boom cylinder 4 through the pipe 9 through the pipe 3, and the boom cylinder 4 extends to raise and lower the boom 3. When the boom cylinder 4 further extends and approaches the stroke end, as shown in FIG. 6A, when the relative distance between the boom 3 and the boom cylinder 4 comes close to reach a preset distance, Is detected by the proximity switch 32, and the detection signal is transmitted to the switching valve 31 via the wiring 33, and the switching valve 31 is switched to the closed position e. Therefore, from the operation means 37 to the pilot conduit 2
The pressure oil supplied to 7 is shut off by the switching valve 31,
The pilot chamber 2 of the directional control valve 23 passes through the bypass pipe 29 and is provided with the pressure reducing valve 30 interposed in the bypass pipe 29.
The pressure supplied to 3a is controlled to a preset pressure.
The set pressure is a pressure for adjusting the switching amount of the direction switching valve 23 to the neutral position side so that the impact at the stroke end of the boom cylinder 4 is reduced. Therefore, the flow rate of the pressure oil supplied to the head side oil chamber 4a of the boom cylinder 4 is limited, and the impact at the stroke end of the boom cylinder 4 is reduced.

According to this embodiment, the pilot line 27
Since the pressure of the pressure reducing valve 3 is lower than the pressure of the pipelines 9 and 10, the pressure reducing valve 3
0, the outer shape of the switching valve 31 can be reduced. Further, since the proximity switch 32 is within the width of the rod of the boom 3 and is surrounded by the brackets 3a and 3b provided on the boom 3, it is protected from obstacles such as earth and sand and rocks. Further, the proximity switch 32 for detecting the distance between the boom 3 and the boom cylinder 4 and the control means 43 for controlling the drive speed of the boom cylinder 4 are separated, and the control means 43 is provided on the upper swing body 2 of the hydraulic excavator. As a result, it will not come into contact with soil, rocks, etc. during work.

Here, the distance between the boom and the boom cylinder becomes maximum in the vicinity of the center (b) of the stroke of the cylinder, as shown in FIG. 6, and even if the boom is driven in the extension direction (a), the distance is reduced in the contraction direction. It is smaller even after driving (c). Therefore, by providing the above-mentioned pressure limiting means only in the other pilot conduit 28, it is possible to perform control only during reduction. Further, by providing the pilot lines 27 and 28 in both directions, one boom switch may control the boom cylinder drive speed during extension and contraction.

Next, a second embodiment will be described with reference to FIG. The same components as those of the first embodiment described above are designated by the same reference numerals and the description thereof will be omitted. In the figure, 42 is a switching valve provided on the upper revolving structure 2 and having two positions of a communication position g and a flow rate limiting position f and interposed in the pipe line 9 as a flow rate limiting means. Is connected to the proximity switch 32 via a wire 33 which is a transmission means of the wire 33, and the wire 33 is arranged on the side surface of the boom 3.

According to the above structure, the operation lever 36
Is operated in the direction of arrow a in the figure, the pressure oil discharged from the hydraulic pump 38 is supplied to the pilot conduit 27 by the operating means 37.
Is supplied to. The pressure oil supplied to the pilot conduit 27 is supplied to the pilot chamber 23a of the direction switching valve 23,
The direction switching valve is switched to the left position in the figure. As a result, the pressure oil discharged from the main hydraulic pump 20 passes through the duct 9 via the direction switching valve 23 and is supplied to the head-side oil chamber 4a of the boom cylinder 4 so that the boom cylinder 4 extends and the boom is expanded. 3 moves down. Then, when the boom cylinder 4 further extends and approaches the stroke end, as shown in FIG.
As shown in (a), the relative distance between the boom 3 and the boom cylinder 4 becomes shorter, and the proximity switch 32 detects that the distance is closer than a preset distance, and the detection signal from the proximity switch 32 is wired. It is transmitted to the switching valve 42 via 33, and the switching valve 42 switches to the flow rate control position f. Therefore, the pressure oil discharged from the main hydraulic pump 20 is supplied to the head side oil chamber 4a of the boom cylinder 4 by the flow rate control position f of the switching valve 42 via the direction switching valve 23, and the flow rate of the pressure oil is limited. The drive speed of the boom cylinder 4 becomes slow. Here, the flow rate control position f is set so as to supply the flow rate to the head side oil chamber 4a such that the impact of the boom cylinder 4 at the stroke end is reduced.

According to this embodiment, in addition to the effect of the first embodiment, by interposing the switching valve 42 in the conduit 9 on one side, both strokes of the boom cylinder 4 when it is extended and when it is contracted are reduced. The drive speed at the end can be controlled.

In the first and second embodiments, the proximity switch which is a non-contact type is used as the detecting means, but a contact type limit switch may be used, that is, the boom 3
Any detection means capable of detecting that the distance between the boom cylinder 4 and the boom cylinder 4 has reached a preset position may be used.

Further, in the first and second embodiments, the proximity switch for outputting an ON-OFF signal is used as the detecting means, but instead of this, an electric signal corresponding to the distance between the boom 3 and the boom cylinder 4 is used. Is used to send a signal to the wiring on the upper revolving structure 2 as a transmission means to cause the controller on the upper revolving structure 2 to perform a comparison calculation with respect to a preset distance to control the pressure limiting means or the flow rate limiting means. By outputting the signal for, for example, the operator can arbitrarily set the driving speed near the stroke end of the boom cylinder 4 according to the working condition, or arbitrarily change the stroke position for changing the driving speed. can do.

[0029]

As described above, according to the hydraulic shock absorber control device for a construction machine of the present invention, the stroke end condition of the boom cylinder can be detected by the simple detecting means attached to the abdomen of the boom, and the detection thereof. By forming the means within the width of the rod of the boom cylinder, it is possible to prevent contact with earth and sand, rocks and the like during work.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a hydraulic shock absorber control device for a construction machine according to a first embodiment of the present invention.

FIG. 2 is a front view of the construction machine of the present invention.

FIG. 3 is a side view of the construction machine of the present invention.

FIG. 4 is an enlarged view of part (a) of FIG.

5 is an enlarged view of part (b) of FIG.

FIG. 6 is a diagram showing a distance between a boom and a boom cylinder with respect to expansion and contraction of the boom cylinder.

FIG. 7 is a circuit diagram of a hydraulic shock absorber control device for a construction machine according to a second embodiment of the present invention.

FIG. 8 is an overall view of a conventional construction machine.

FIG. 9 is a diagram showing the amount of movement of the boom with respect to displacement of the stroke of the cylinder near the stroke end on the extension side of the boom cylinder.

FIG. 10 is a diagram showing the amount of movement of the boom with respect to displacement of the stroke of the cylinder near the center of the stroke of the boom cylinder.

FIG. 11 is a graph showing the relationship between the displacement of the stroke of the boom cylinder and the angular velocity of the boom.

FIG. 12 is an overall view of a hydraulic buffer control device for a construction machine according to a conventional technique.

FIG. 13 is an enlarged view of a main part of a hydraulic buffer control device for a construction machine according to a conventional technique.

FIG. 14 is a sectional view of a variable throttle valve of a hydraulic shock absorber control device for a construction machine according to a conventional technique.

[Explanation of symbols]

 2 Working machine body 3 Boom 3a Bracket 3b Bracket 4 Boom cylinder 4a Head side oil chamber 4b Rod side oil chamber 9 Pipe line 10 Pipe line 20 Main hydraulic pump 23 Directional switching valve 23a First pilot valve 23b Second pilot valve 27 First pilot line 28 Second pilot line 32 Detection means 34 First pilot valve 35 Second pilot valve 37 Operating means 38 Pressure oil source 41 Tank 42 Flow rate limiting means 44 Pressure limiting means

Claims (5)

[Claims] 1. A work machine main body, a boom whose one end is rotatably connected to the work machine main body, a boom cylinder for raising and lowering the boom, and a direction switching for controlling extension / contraction drive of the boom cylinder. A valve, a first pilot chamber provided on one side of the directional control valve and a second pilot chamber provided on the other side, and a first pilot valve and a second pilot valve for operating the directional control valve A tank connected to the first and second pilot valves and a pressure oil source, a first pilot line connecting the first pilot valve and the first pilot chamber, a second pilot valve and a second pilot valve, In a construction machine provided with a second pilot conduit connecting two pilot chambers, a detection means for detecting the relative distance between the boom and the boom cylinder is formed within the width of the rod of the boom cylinder, and the detection means is provided. The The pressure limiting means attached to the belly face of the boom near the rod end of the boom cylinder and provided on the work machine body is provided on at least one side of the first and second pilot pipelines, and the first and second pilots are provided. A hydraulic shock absorber control device for a construction machine, wherein the pressure on the side of the chamber where the pressure limiting means is provided is controlled to decrease. 2. A working machine body, a boom whose one end is rotatably connected to the working machine body, and pressure oil discharged from a hydraulic pump is supplied to a head side oil chamber or a rod side oil chamber of a boom cylinder. In a construction machine equipped with a direction switching valve that guides the return pressure oil from the head-side oil chamber or the rod-side oil chamber to the tank, the detection means for detecting the relative distance between the boom and the boom cylinder is a rod of the boom cylinder. And the detection means is attached to the abdominal surface of the boom near the rod end of the boom cylinder to reduce the flow rate of the pressure oil supplied from the hydraulic pump to the boom cylinder so that the boom drive speed is reduced. A hydraulic shock absorber control device for a construction machine, comprising: 3. A pair of left and right brackets for connecting a boom cylinder to each other, the pair of left and right brackets being fixed to the abdominal surface of the boom, and the detection means attached to the boom within the pair of bracket widths. Item 2. A hydraulic shock absorber control device for a construction machine according to Item 2. 4. The hydraulic shock absorber control device for a construction machine according to claim 1, 2, or 3, wherein the detection means is a contact type switch. 5. The detection means is a non-contact type switch, claim 2, or claim 3
A hydraulic shock absorber control device for a construction machine as described.