JP2021025232A - Construction machine - Google Patents

Abstract

To provide a construction machine capable of suppressing slid vibration of a hydraulic actuator.SOLUTION: A shovel 100 as a construction machine is provided with: a cylinder body 8S of an arm cylinder 8 as a first member; an O-ring 60 as a second member sliding in the cylinder body 8S; and a resistance control mechanism RM increasing/decreasing slide resistance between the cylinder body 8S and the O-ring 60 corresponding to external commands. The O-ring 60 and a changeover valve 65 constitute the resistance control mechanism RM increasing/decreasing the slide resistance between the cylinder body 8S and the O-ring 60.SELECTED DRAWING: Figure 3

Description

This disclosure relates to construction machinery.

Conventionally, an excavator having an attachment driven by a double-acting single-rod type hydraulic cylinder is known (see Patent Document 1). This hydraulic cylinder expands when the hydraulic oil flows into the bottom oil chamber and the hydraulic oil flows out from the rod side oil chamber, and when the hydraulic oil flows into the rod side oil chamber and the hydraulic oil flows out from the bottom oil chamber. It is configured to contract.

Japanese Unexamined Patent Publication No. 2013-130227

However, the hydraulic cylinder causes minute expansion / contraction vibration at the start of expansion due to the low rigidity characteristic due to the compressibility of the hydraulic oil. Then, this expansion / contraction vibration continues for a certain period of time. The same applies at the end of extension, the start of contraction, and the end of contraction. Such expansion and contraction vibration adversely affects the workability and operability of the excavator.

Therefore, it is desirable to suppress the sliding vibration of the hydraulic actuator such as the expansion and contraction vibration of the hydraulic cylinder.

The construction machine according to the embodiment of the present invention is between the first member, the second member sliding with respect to the first member, and the first member and the second member in response to an external command. It is equipped with a resistance adjusting mechanism that increases or decreases the sliding resistance of the above.

By the above-mentioned means, a construction machine capable of suppressing the sliding vibration of the hydraulic actuator is provided.

It is a side view of an excavator. It is a block diagram which shows the structural example of the drive system of an excavator. It is a figure which shows the structural example of a part of the hydraulic system mounted on an excavator. It is sectional drawing of an O-ring. It is a figure which shows the time transition of the extension speed of an arm cylinder. It is a figure which shows another example of the resistance adjustment mechanism. It is a figure which shows still another example of a resistance adjustment mechanism.

First, an excavator (excavator 100) as a construction machine according to an embodiment of the present invention will be described with reference to FIG. The construction machine may be a crane. FIG. 1 is a side view of the excavator 100. The lower traveling body 1 of the excavator 100 shown in FIG. 1 is mounted with the upper rotating body 3 via the turning mechanism 2. A boom 4 as a working element is attached to the upper swing body 3. An arm 5 as a working element is attached to the tip of the boom 4, and a working element and a bucket 6 as an end attachment are attached to the tip of the arm 5. The boom 4, the arm 5, and the bucket 6 form an excavation attachment as an attachment. The boom 4 is driven by the boom cylinder 7, the arm 5 is driven by the arm cylinder 8, and the bucket 6 is driven by the bucket cylinder 9. The upper swing body 3 is provided with a cabin 10 as a driver's cab, and is equipped with a power source such as an engine 11.

FIG. 2 is a block diagram showing a configuration example of the drive system of the excavator 100 of FIG. 1, and the mechanical power system, the high-pressure hydraulic line, the pilot line, and the electric control system are shown as double lines, thick solid lines, broken lines, and electric control systems, respectively. It is indicated by a alternate long and short dash line.

The drive system of the excavator 100 mainly includes an engine 11, a regulator 13, a main pump 14, a pilot pump 15, a control valve 17, an operating device 26, a discharge pressure sensor 28, an operating pressure sensor 29, a controller 30, and the like.

The engine 11 is a drive source for the excavator 100. In the present embodiment, the engine 11 is, for example, a diesel engine as an internal combustion engine that operates so as to maintain a predetermined rotation speed. The output shaft of the engine 11 is connected to each input shaft of the main pump 14 and the pilot pump 15.

The main pump 14 is configured to supply hydraulic oil to the control valve 17 via a hydraulic oil line. In the present embodiment, the main pump 14 is a swash plate type variable displacement hydraulic pump.

The regulator 13 is configured to control the discharge amount of the main pump 14. In the present embodiment, the regulator 13 controls the retreat volume of the main pump 14 per rotation by adjusting the tilt angle of the swash plate of the main pump 14 in response to a command from the controller 30.

The pilot pump 15 is configured to supply hydraulic oil to various flood control devices including an operating device 26 via a pilot line. In the present embodiment, the pilot pump 15 is a fixed displacement hydraulic pump. However, the pilot pump 15 may be omitted. In this case, the function carried out by the pilot pump 15 may be realized by the main pump 14. That is, even if the main pump 14 has a function of supplying hydraulic oil to the operating device 26 or the like after reducing the pressure of the hydraulic oil by a throttle or the like, in addition to the function of supplying the hydraulic oil to the control valve 17. Good.

The control valve 17 is a flood control device that controls the flood control system in the excavator 100. In the present embodiment, the control valve 17 includes a plurality of control valves that control the flow of hydraulic oil discharged by the main pump 14. Then, the control valve 17 selectively supplies the hydraulic oil discharged by the main pump 14 to one or a plurality of hydraulic actuators through these control valves. These control valves control the flow rate of the hydraulic oil flowing from the main pump 14 to the hydraulic actuator and the flow rate of the hydraulic oil flowing from the hydraulic actuator to the hydraulic oil tank. In the example of FIG. 2, the hydraulic actuator includes a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a left traveling hydraulic motor 1L, a right traveling hydraulic motor 1R, and a turning hydraulic motor 2A. The swivel hydraulic motor 2A is an example of a swivel device that swivels the upper swivel body 3 with respect to the lower traveling body 1, and may be replaced with a swivel electric motor as an electric actuator.

The operating device 26 is a device used by the operator to operate the actuator. The actuator includes at least one of a hydraulic actuator and an electric actuator. In the present embodiment, the operating device 26 supplies the hydraulic oil discharged by the pilot pump 15 to the pilot ports of the control valves corresponding to the respective hydraulic actuators via the pilot line. The pressure of the hydraulic oil supplied to each of the pilot ports (hereinafter referred to as "pilot pressure") depends on the operation direction and operation amount of the operation lever or operation pedal as the operation device 26 corresponding to each of the hydraulic actuators. Pressure.

The operating pressure sensor 29 is configured to detect the operation content of the operator using the operating device 26. In the present embodiment, the operating pressure sensor 29 detects the operating direction and operating amount of the operating device 26 corresponding to each of the hydraulic actuators in the form of pressure, and outputs the detected value to the controller 30. The operation content of the operation device 26 may be detected by using a sensor other than the operation pressure sensor 29.

The controller 30 is a control device for controlling the excavator 100. In the present embodiment, the controller 30 is composed of, for example, a computer including a CPU, RAM, ROM, and the like. The controller 30 realizes various functions by reading programs corresponding to various functions from the ROM, loading them into the RAM, and causing the CPU to execute the corresponding processes.

Next, with reference to FIG. 3, the expansion / contraction vibration suppression function, which is an example of the function realized by the controller 30, will be described. FIG. 3 is a schematic view showing a partial configuration example of the hydraulic system mounted on the excavator 100 of FIG. Specifically, FIG. 3 shows a configuration example of a portion of the hydraulic system related to the arm cylinder 8. In the example of FIG. 3, the expansion / contraction vibration suppression function is a function of suppressing expansion / contraction vibration generated when the arm cylinder 8 is extended or contracted.

The arm cylinder 8 is a double-acting single-rod type hydraulic cylinder provided with a rod 8X extending to one side of a piston 8P slidably arranged in a cylindrical cylinder body 8S. The arm cylinder 8 is connected to the main pump 14 via a control valve 170 arranged in the control valve 17. Specifically, the rod-side oil chamber 8R of the arm cylinder 8 is connected to the control valve 170 via the first oil passage C1, and the bottom-side oil chamber 8B of the arm cylinder 8 is connected to the control valve 170 via the second oil passage C2. It is connected to the control valve 170.

The control valve 170 is configured to operate in response to a pilot pressure generated by the arm operating lever 26A, which is an example of the operating device 26. In the example of FIG. 3, the arm operating lever 26A is connected to the pilot pump 15 via the pilot line PL1. Then, the pilot pressure (secondary pressure) is generated by utilizing the pressure (primary pressure) of the hydraulic oil discharged by the pilot pump 15. Specifically, when the arm operating lever 26A is operated in the arm opening direction, the pilot pressure in the pilot line PL2 is increased to move the control valve 170 to the right. Further, when the arm operating lever 26A is operated in the arm closing direction, the pilot pressure in the pilot line PL3 is increased to move the control valve 170 to the left.

When the control valve 170 moves to the right, the main pump 14 causes the hydraulic oil pumped from the hydraulic oil tank TK to flow into the rod-side oil chamber 8R of the arm cylinder 8 to expand the rod-side oil chamber 8R. As a result, the rod 8X is retracted into the cylinder body 8S and the arm 5 is opened. When the control valve 170 moves to the left, the main pump 14 causes the hydraulic oil pumped from the hydraulic oil tank TK to flow into the bottom oil chamber 8B of the arm cylinder 8 to expand the bottom oil chamber 8B. As a result, the rod 8X is pushed out from the inside of the cylinder body 8S and the arm 5 is closed.

An O-ring 60 is arranged between each of the piston 8P and the rod 8X and the cylinder body 8S. Specifically, the O-ring 60 includes a first O-ring 60a to a third O-ring 60c.

The O-ring 60 is configured to change in volume as needed. In the example of FIG. 3, the O-ring 60 is made of rubber having a hollow structure. The O-ring 60 is configured so that its volume expands when the fluid flows into the inside. In this embodiment, the fluid is the hydraulic oil discharged by the pilot pump 15. However, the fluid may be a fluid other than the hydraulic oil, that is, a fluid discharged by a dedicated pump other than the pilot pump 15.

FIG. 4 shows a cross-sectional view of the O-ring 60. The dotted line in FIG. 4 shows the O-ring 60 when expanded. In the example of FIG. 4, the O-ring 60 is configured to receive fluid through the opening 60K. Further, the O-ring 60 is configured to expand toward the inner diameter side as shown by the arrow AR1 and to expand toward the outer diameter side as shown by the arrow AR2. However, the O-ring 60 may be configured to expand substantially only on the inner diameter side, or may be configured to expand substantially only on the outer diameter side.

The first O-ring 60a is provided between the rod 8X and the cylinder body 8S so as to prevent the hydraulic oil in the rod-side oil chamber 8R from leaking to the outside through the gap between the rod 8X and the cylinder body 8S. is set up. Specifically, the first O-ring 60a is fitted into a ring groove formed in a through hole through which the rod 8X is inserted at the rod-side end of the cylinder body 8S.

The second O-ring 60b is provided on the cylindrical surface of the piston 8P so as to prevent the hydraulic oil in the rod-side oil chamber 8R from leaking to the bottom-side oil chamber 8B through the gap between the piston 8P and the cylinder body 8S. It is installed between the rod side end and the cylinder body 8S. Specifically, the second O-ring 60b is fitted into a ring groove formed at the end on the rod side.

The third O-ring 60c is provided on the cylindrical surface of the piston 8P so as to prevent the hydraulic oil in the bottom oil chamber 8B from leaking to the rod-side oil chamber 8R through the gap between the piston 8P and the cylinder body 8S. It is installed between the bottom end and the cylinder body 8S. Specifically, the third O-ring 60c is fitted into a ring groove formed at the bottom end.

The switching valve 65 is a solenoid valve that operates in response to a command from the controller 30. In the example of FIG. 3, the switching valve 65 has a first valve position that opens the pipeline connecting the pilot pump 15 and the O-ring 60 and closes the pipeline connecting the O-ring 60 and the hydraulic oil tank TK. , The second valve position that opens the pipeline connecting the pilot pump 15 and the hydraulic oil tank TK and opens the pipeline connecting the O-ring 60 and the hydraulic oil tank TK is configured to be switchable. There is. The numbers in parentheses in FIG. 3 indicate the valve positions of the switching valve 65. Further, FIG. 3 shows a state in which the switching valve 65 is switched to the second valve position. The switching valve 65 may be controlled to be located at an intermediate valve position between the first valve position and the second valve position. In this case, the intermediate valve position may be set steplessly. Alternatively, the switching valve 65 has a third valve position that opens the pipeline connecting the pilot pump 15 and the hydraulic oil tank TK and closes the pipeline connecting the O-ring 60 and the hydraulic oil tank TK. May be good. Alternatively, the switching valve 65 may be configured so that at least two degrees of expansion of the first O-ring 60a to the third O-ring 60c can be controlled separately. In this case, the switching valve 65 may be composed of a plurality of solenoid valves.

For example, the controller 30 outputs an open command to the switching valve 65 and sets the switching valve 65 to the first valve position so that hydraulic oil can flow into the O-ring 60 and the volume of the O-ring 60 can be expanded. it can. Further, for example, the controller 30 outputs a closing command to the switching valve 65, and by setting the switching valve 65 to the second valve position, the hydraulic oil is discharged from the inside of the O-ring 60, and the volume of the expanded O-ring 60 is reached. Can be undone.

The O-ring 60 and the switching valve 65 that function as described above constitute a resistance adjusting mechanism RM that increases or decreases the sliding resistance between the cylinder body 8S and the O-ring 60.

The arm rod pressure sensor 28R detects the pressure of the hydraulic oil (hereinafter, referred to as “arm rod pressure”) in the rod side oil chamber 8R of the arm cylinder 8. In the example of FIG. 3, the arm rod pressure sensor 28R is arranged in the first oil passage C1. However, the arm rod pressure sensor 28R may be attached to the rod side oil chamber 8R. The arm bottom pressure sensor 28B detects the pressure of hydraulic oil in the bottom side oil chamber 8B of the arm cylinder 8 (hereinafter, referred to as “arm bottom pressure”). In the example of FIG. 3, the arm bottom pressure sensor 28B is arranged in the second oil passage C2. However, the arm bottom pressure sensor 28B may be attached to the bottom side oil chamber 8B. The arm bottom pressure sensor 28B and the arm rod pressure sensor 28R output the detected values to the controller 30.

The controller 30 may be configured so that the valve position of the switching valve 65 can be switched according to the pressure of the hydraulic oil in the O-ring 60 (hereinafter, referred to as “internal pressure”). In this case, the resistance adjusting mechanism RM may include an internal pressure sensor 66 in the pipeline between the O-ring 60 and the switching valve 65 so that the internal pressure of the O-ring 60 can be detected. That is, the controller 30 may be configured so that the internal pressure in the O-ring 60 can be adjusted to a desired pressure according to the output of the internal pressure sensor 66.

The controller 30 includes a discharge pressure sensor 28, an arm bottom pressure sensor 28B, an arm rod pressure sensor 28R, an operating pressure sensor 29, an internal pressure sensor 66, a boom angle sensor, an arm angle sensor, a bucket angle sensor, a machine body tilt sensor, and a turning angle speed sensor. It may be configured to control the resistance adjusting mechanism RM based on at least one of the outputs of various sensors such as. Specifically, the controller 30 has the presence / absence of operation of the arm operation lever, the operation amount, the operation direction, the arm rod pressure, the arm bottom pressure, the internal pressure of the O-ring 60, the discharge pressure of the main pump 14, the posture of the excavation attachment, and the posture. , The resistance adjusting mechanism RM may be controlled based on at least one of the positional relationship (moment of inertia and elastic characteristics) of the excavation attachment.

The controller 30 determines, for example, whether or not the arm operating lever 26A has been operated based on the output of the operating pressure sensor 29. Then, when the controller 30 determines that the arm operating lever 26A has been operated, it determines whether or not expansion / contraction vibration of the arm cylinder 8 is generated based on the outputs of the arm bottom pressure sensor 28B and the arm rod pressure sensor 28R. .. The excavator 100 may include a stroke sensor that detects the stroke amount of the arm cylinder 8. In this case, the controller 30 may determine whether or not expansion / contraction vibration of the arm cylinder 8 is generated based on the output of the stroke sensor.

Then, when it is determined that the expansion / contraction vibration of the arm cylinder 8 is generated, the controller 30 determines, for example, the target expansion / contraction speed of the arm cylinder 8 corresponding to the lever operation amount of the arm operation lever 26A based on the outputs of various sensors. calculate. The target expansion / contraction speed includes a target expansion speed and a target contraction speed. Specifically, when the arm operating lever 26A is operated in the arm closing direction, the controller 30 calculates the target extension speed of the arm cylinder 8 corresponding to the lever operating amount of the arm operating lever 26A. Alternatively, when the arm operating lever 26A is operated in the arm opening direction, the controller 30 calculates the target contraction speed of the arm cylinder 8 corresponding to the lever operating amount of the arm operating lever 26A.

Then, the controller 30 controls the resistance adjusting mechanism RM so that the actual expansion / contraction speed of the arm cylinder 8 becomes the target expansion / contraction speed. Specifically, in the controller 30, for example, the O-ring 60 expands as the amplitude of the expansion / contraction vibration of the arm cylinder 8, that is, the difference between the actual expansion / contraction speed of the arm cylinder 8 and the target expansion / contraction speed increases. , The valve position of the switching valve 65 is switched so that the internal pressure of the O-ring 60 becomes large.

FIG. 5 shows the temporal transition of the extension speed V of the arm cylinder 8 when the arm operation lever 26A is operated in the arm closing direction. The thick dotted line in FIG. 5 shows the temporal transition of the extension speed V of the arm cylinder 8 when the resistance adjustment mechanism RM is not used, and the thick solid line in FIG. 5 shows the arm when the resistance adjustment mechanism RM is used. The time transition of the extension speed V of the cylinder 8 is shown. When the resistance adjustment mechanism RM is not used, the extension speed V of the arm cylinder 8 is typically represented by a secondary lag system as shown by a thick dotted line, and has a characteristic that vibration is sustained at a resonance frequency. ..

When the resistance adjustment mechanism RM is not used and the arm operating lever 26A is operated in the arm closing direction at time t1, the extension speed V of the arm cylinder 8 corresponds to the lever operating amount of the arm operating lever 26A while repeatedly increasing and decreasing. It converges to the extension speed V1. That is, the arm cylinder 8 expands while generating expansion and contraction vibration due to the low rigidity characteristic due to the compressibility of the hydraulic oil.

On the other hand, when the resistance adjusting mechanism RM is used, when the arm operating lever 26A is operated in the arm closing direction at time t1, the extension speed V of the arm cylinder 8 is the same as when the resistance adjusting mechanism RM is not used. Increases to. However, when the resistance adjustment mechanism RM is used, the controller 30 calculates the target expansion speed Vt (= V1) when it determines that expansion / contraction vibration is generated based on the outputs of various sensors at time t2. Then, the current extension speed V is brought closer to the target extension speed Vt.

Specifically, the controller 30 O-rings as the difference between the current stretching speed V and the target stretching speed Vt increases, regardless of whether the current stretching speed V is larger or smaller than the target stretching speed Vt. The movement of the switching valve 65 is controlled so that the internal pressure of the ring 60 becomes large. This is because the larger the internal pressure of the O-ring, the more the O-ring 60 expands. This is because as the O-ring 60 expands, the contact pressure (friction force) between the O-ring 60 and each of the cylinder body 8S, the piston 8P, and the rod 8X increases, and the sliding resistance also increases.

Further, when the difference between the current extension speed V and the target extension speed Vt is equal to or less than a predetermined value, the controller 30 switches the valve position of the switching valve 65 to the second valve position so that the O-ring 60 does not expand. It may be configured as follows. This is to prevent the extension of the arm cylinder 8 from being unnecessarily hindered. Specifically, this is to prevent the durability of each member from being deteriorated and the fuel consumption from being deteriorated by uniformly increasing the frictional force. Further, it is for preventing the workability of excavation work and the like from being deteriorated by uniformly increasing the sliding resistance. The predetermined value may be zero.

As a result, the vibration of the extension speed V of the arm cylinder 8 is substantially attenuated by the time t3, and after the time t3, the extension speed V of the arm cylinder 8 changes while maintaining the target extension speed Vt. Further, after time t3, the difference between the actual extension speed V and the target extension speed Vt is almost zero, so that the controller 30 sets the valve position of the switching valve 65 so that the O-ring 60 does not expand. Switch to the 2-valve position. Therefore, after the time t3, the extension of the arm cylinder 8 is not unnecessarily hindered.

In the above example, the controller 30 operates so as to suppress the expansion / contraction vibration of the arm cylinder 8 that occurs when the arm closing operation by the arm operating lever 26A is started, but when the arm closing operation is completed. The same operation is performed when suppressing the expansion and contraction vibration of the arm cylinder 8 that is generated.

Further, in the above example, the controller 30 operates so as to suppress the vibration of the extension speed V of the arm cylinder 8 when the arm 5 is closed, that is, when the arm cylinder 8 is extended, but when the arm 5 is opened. That is, the same operation is performed when suppressing the vibration of the extension speed V of the arm cylinder 8 when the arm cylinder 8 is contracted.

Further, the controller 30 suppresses the vibration of the expansion / contraction speed of the hydraulic cylinder generated when the boom 4 is raised, when the boom 4 is lowered, when the bucket 6 is opened, and when the bucket 6 is closed. Works in the same way. Further, the controller 30 is configured to operate in the same manner when suppressing the vibration of the rotational speed of the hydraulic motor generated when the upper swing body 3 is swiveled and when the lower traveling body 1 is rotated. It may have been done.

Next, another example of the resistance adjusting mechanism RM will be described with reference to FIG. FIG. 6 is a diagram showing another configuration example of a part of the hydraulic system mounted on the excavator 100, and corresponds to FIG. The resistance adjusting mechanism RM of FIG. 6 is provided with an O-ring 60N configured so as not to expand the volume instead of the O-ring 60 configured to expand the volume, and a hydraulic clamp 61 is provided. , Different from the resistance adjustment mechanism RM of FIG. Therefore, the explanation of the common part is omitted, and the difference part is explained in detail.

The O-ring 60N is configured so that the volume does not change. In the example of FIG. 6, the O-ring 60N is made of rubber having a solid structure.

The hydraulic clamp 61 constitutes a resistance adjusting mechanism RM that increases or decreases the sliding resistance between the cylinder body 8S and the O-ring 60N. Specifically, the hydraulic clamp 61 is attached to the rod-side end of the cylinder body 8S on the outside of the cylinder body 8S of the arm cylinder 8. The hydraulic clamp 61 has a pair of rubbers 61a and 61b that are pressed against the rod 8X of the arm cylinder 8. In the example of FIG. 6, each of the pair of rubbers 61a and 61b has a partial cylindrical shape that matches the shape of the rod 8X, and is arranged so as to surround the circumferential surface of the rod 8X.

The hydraulic clamp 61 constituting the resistance adjusting mechanism RM may be replaced by another hydraulic drive unit such as a mechanism including a hydraulic cylinder, or may be replaced by an electric drive unit such as an electric clamp.

The controller 30 presses the pair of rubbers 61a and 61b against the rod 8X by switching the valve position of the switching valve 65 from the second valve position to the first valve position, and between the pair of rubbers 61a and 61b and the rod 8X. The contact pressure (friction force) and, by extension, the sliding resistance can be increased. As a result, the controller 30 can substantially increase the sliding resistance between the cylinder body 8S and the O-ring 60N. Further, the controller 30 separates the pair of rubbers 61a and 61b from the rod 8X by switching the valve position of the switching valve 65 from the first valve position to the second valve position, and causes the pair of rubbers 61a and 61b and the rod 8X to be separated from each other. The contact pressure (friction force) between them, and thus the sliding resistance, can be reduced or eliminated. As a result, the controller 30 can substantially reduce the sliding resistance between the cylinder body 8S and the O-ring 60N.

With this configuration, the controller 30 can increase or decrease the sliding resistance between the cylinder body 8S and the O-ring 60 at an arbitrary timing, as in the case of using the hollow O-ring 60 in FIG. Therefore, the controller 30 can suppress the vibration of the extension speed of the arm cylinder 8 when the arm cylinder 8 is extended, and can suppress the vibration of the contraction speed of the arm cylinder 8 when the arm cylinder 8 is contracted.

Next, still another example of the resistance adjusting mechanism RM will be described with reference to FIG. 7. FIG. 7 is a diagram showing another configuration example of a part of the hydraulic system mounted on the excavator 100. Specifically, the main part of FIG. 7 shows a cross section of the excavation attachment when a part of the virtual plane parallel to the XY plane including the alternate long and short dash line L1 of FIG. 1 is viewed from the + Z side.

The connecting pin CP is a pin that connects the boom 4 and the arm 5, and both ends thereof are non-rotatably attached to a pair of side plate portions 4L and 4R constituting the boom 4. Further, the connecting pin CPs are attached to the pair of side plate portions 5L and 5R constituting the arm 5 so as to be relatively rotatable at two locations in the central portion thereof. Specifically, the connecting pin CP is rotatably attached to the arm 5 via the bush 50. The bush 50 includes a bush 50L attached to the side plate portion 5L and a bush 50R attached to the side plate portion 5R.

The hydraulic clamp 61E constituting the resistance adjusting mechanism RM shown in FIG. 7 is configured to increase or decrease the sliding resistance between the connecting pin CP and the bush 50, and the O-ring 60 and the O-ring 60. It is different from the hydraulic clamp 61 that constitutes the resistance adjustment mechanism RM shown in FIG. 3, which is configured so that the sliding resistance with the cylinder body 8S can be increased or decreased. Therefore, the explanation of the common part is omitted, and the difference part is explained in detail.

The hydraulic clamp 61E constitutes a resistance adjusting mechanism RM that substantially increases or decreases the sliding resistance between the connecting pin CP and the bush 50. Specifically, the hydraulic clamp 61E is attached to the arm 5 between the side plate portion 5L and the side plate portion 5R constituting the arm 5. The hydraulic clamp 61E has a pair of rubbers 61Ea and 61Eb that are pressed against the connecting pin CP. In the example of FIG. 7, each of the pair of rubbers 61Ea and 61Eb has a partial cylindrical shape that matches the shape of the connecting pin CP, and is arranged so as to surround the circumferential surface of the connecting pin CP.

The hydraulic clamp 61E constituting the resistance adjusting mechanism RM may be replaced by another hydraulic drive unit such as a mechanism including a hydraulic cylinder, or may be replaced by an electric drive unit such as an electric clamp.

By switching the valve position of the switching valve 65 from the second valve position to the first valve position, the controller 30 presses the pair of rubbers 61Ea and 61Eb against the connecting pin CP, and the pair of rubbers 61Ea and 61Eb and the connecting pin CP The contact pressure (friction force) between them, and thus the sliding resistance, can be increased. As a result, the controller 30 can substantially increase the sliding resistance between the connecting pin CP and the bush 50. Further, the controller 30 separates the pair of rubbers 61Ea and 61Eb from the connecting pin CP by switching the valve position of the switching valve 65 from the first valve position to the second valve position, and separates the pair of rubbers 61Ea and 61Eb from the connecting pin CP. The contact pressure (friction force) with and, by extension, the sliding resistance can be reduced or eliminated. As a result, the controller 30 can substantially reduce the sliding resistance between the connecting pin CP and the bush 50.

With this configuration, the controller 30 can increase or decrease the sliding resistance between the connecting pin CP and the bush 50 at an arbitrary timing. Therefore, the controller 30 can suppress the vibration of the extension speed of the arm cylinder 8 when the arm cylinder 8 is extended, and can suppress the vibration of the contraction speed of the arm cylinder 8 when the arm cylinder 8 is contracted.

As described above, the excavator 100 as a construction machine according to the embodiment of the present invention includes a first member, a second member that slides with respect to the first member, and a first member in response to an external command. It is provided with a resistance adjusting mechanism RM that increases or decreases the sliding resistance with the second member. The first member is, for example, the cylinder body 8S of the arm cylinder 8, and the second member is, for example, an O-ring 60 attached to the piston 8P of the arm cylinder 8. Alternatively, the first member is, for example, a connecting pin CP that connects the boom 4 and the arm 5, and the second member is, for example, a bush 50 that is arranged between the arm 5 and the connecting pin CP. With this configuration, the excavator 100 as a construction machine can suppress the expansion and contraction vibration of a hydraulic actuator such as an arm cylinder 8. Therefore, the excavator 100 can suppress the adverse effect of the expansion / contraction vibration of the hydraulic actuator on the workability and operability of the excavator 100. As a result, the excavator 100 can stabilize the behavior during operation, and can improve the workability of the excavator 100. This is because if the expansion / contraction vibration can be suppressed, the operator does not need to interrupt the work until the expansion / contraction vibration has subsided, and does not need to perform a special operation for suppressing the expansion / contraction vibration.

The resistance adjusting mechanism RM increases the sliding resistance, for example, when the sliding of the second member with respect to the first member starts, or when the sliding of the second member with respect to the first member ends. It may be configured. With this configuration, the resistance adjusting mechanism RM can suppress expansion and contraction vibration of a hydraulic cylinder such as an arm cylinder 8 that occurs when the movement of a working element such as the arm 5 starts or ends, for example.

The resistance adjusting mechanism RM may, for example, increase the sliding resistance when the amplitude of the sliding vibration is equal to or greater than a predetermined value, and decrease the sliding resistance when the amplitude of the sliding vibration is less than a predetermined value. The sliding vibration is, for example, the expansion / contraction vibration of a hydraulic cylinder, the sliding vibration of a hydraulic actuator including the rotational vibration of a hydraulic motor, and the like. Specifically, the resistance adjusting mechanism RM uses the arm when, for example, the amplitude of the expansion / contraction vibration of the arm cylinder 8, that is, the difference between the actual extension speed V of the arm cylinder 8 and the target extension speed Vt is equal to or greater than a predetermined value. The sliding resistance between the cylinder body 8S of the cylinder 8 and the O-ring 60 may be increased, and the sliding resistance may be reduced when the value is less than a predetermined value. With this configuration, the resistance adjusting mechanism RM can quickly attenuate the sliding vibration of the hydraulic actuator that occurs when the movement of the hydraulic actuator starts or ends.

For example, in the example shown in FIG. 3, the resistance adjusting mechanism RM increases the sliding resistance by allowing a fluid to flow into the O-ring 60, and reduces the sliding resistance by causing the fluid in the O-ring 60 to flow out. With this configuration, the resistance adjusting mechanism RM can easily and quickly dampen the sliding vibration of the hydraulic actuator.

The preferred embodiment of the present invention has been described in detail above. However, the present invention is not limited to the embodiments described above. Various modifications or substitutions can be applied to the above-described embodiments without departing from the scope of the present invention. Also, the features described separately can be combined as long as there is no technical conflict.

For example, in the example of FIG. 3 described above, the O-ring 60 has a hollow structure having an opening 60K so that hydraulic oil can flow in and out, but is filled with a fluid whose volume changes according to a predetermined condition. It may have a structure. That is, the O-ring 60 may have a hollow structure that does not have an opening 60K and does not allow fluid to flow in or out. In this case, the fluid enclosed inside the O-ring 60 may be, for example, a ferrofluid.

Further, in the above-mentioned example of FIG. 3, the resistance adjusting mechanism RM adopts a configuration in which the volume of the O-ring 60 is expanded, but a configuration in which the volume of the piston 8P is expanded may be adopted. Similarly, in the example of FIG. 7 described above, the resistance adjusting mechanism RM may adopt a configuration that expands the volume of at least one of the connecting pin CP and the bush 50.

1 ... Lower traveling body 1L ... Left traveling hydraulic motor 1R ... Right traveling hydraulic motor 2 ... Swivel mechanism 2A ... Swivel hydraulic motor 3 ... Upper swivel body 4 ... Boom 4L, 4R ... Side plate 5 ... Arm 5L, 5R ... Side plate 6 ... Bucket 7 ... Boom cylinder 8 ... Arm cylinder 8B ... Bottom side oil chamber 8P ...・ Piston 8R ・ ・ ・ Rod side oil chamber 8S ・ ・ ・ Cylinder body 8X ・ ・ ・ Rod 9 ・ ・ ・ Bucket cylinder 10 ・ ・ ・ Cabin 11 ・ ・ ・ Engine 13 ・ ・ ・ Regulator 14 ・ ・ ・ Main pump 15 ・・ ・ Piston pump 17 ・ ・ ・ Control valve 26 ・ ・ ・ Operating device 26A ・ ・ ・ Arm operating lever 28 ・ ・ ・ Discharge pressure sensor 28B ・ ・ ・ Arm bottom pressure sensor 28R ・ ・ ・ Arm rod pressure sensor 29 ・ ・ ・Operating pressure sensor 30 ... Controller 50, 50L, 50R ... Bush 60, 60N ... O ring 60a ... 1st O ring 60b ... 2nd O ring 60c ... 3rd O ring 60K ... Opening 61 ... Hydraulic clamps 61a, 61b ... Rubber 65 ... Switching valve 66 ... Internal pressure sensor 170 ... Control valve C1 ... 1st oil passage C2 ... 2nd oil passage CP ...・ ・ Connecting pins PL1 to PL3 ・ ・ ・ Piston line RM ・ ・ ・ Resistance adjustment mechanism TK ・ ・ ・ Hydraulic oil tank

Claims (5)

With the first member
A second member that slides with respect to the first member,
A resistance adjusting mechanism for increasing or decreasing the sliding resistance between the first member and the second member in response to an external command is provided.
Construction machinery. The resistance adjusting mechanism increases the sliding resistance when the sliding of the second member with respect to the first member starts, or when the sliding of the second member with respect to the first member ends. ,
The construction machine according to claim 1. The resistance adjusting mechanism increases the sliding resistance when the amplitude of the sliding vibration is equal to or more than a predetermined value, and decreases the sliding resistance when the amplitude of the sliding vibration is less than the predetermined value.
The construction machine according to claim 1 or 2. The first member is a cylinder body of a hydraulic cylinder.
The second member is a hollow O-ring attached to the piston of the hydraulic cylinder.
The resistance adjusting mechanism increases the sliding resistance by allowing a fluid to flow into the O-ring, and reduces the sliding resistance by flowing out the fluid in the O-ring.
The construction machine according to any one of claims 1 to 3. The resistance adjusting mechanism increases the sliding resistance when the amplitude of the expansion / contraction vibration of the hydraulic cylinder is equal to or more than a predetermined value, and reduces the sliding resistance when the amplitude of the expansion / contraction vibration of the hydraulic cylinder is less than a predetermined value.
The construction machine according to claim 4.

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