Wheeled construction machinery

Abstract

A control device for a wheeled hydraulic shovel according to the present invention controls the flow of pressure oil from a hydraulic cylinder that drives a work device, and executes control of a vibration suppression function that suppresses the vibration of the hydraulic cylinder when the rotation speed of a wheel reaches a predetermined value or more. Furthermore, even when the control of the vibration suppression function is enabled by an instruction from a vibration suppression instructing device, if the vehicle body is jacked up by the work device, the control device disables the control of the vibration suppression function.

Description

Technical Field

[0001] The present invention relates to a wheel-type construction machine, and more particularly to a wheel-type construction machine having a vibration suppression function for suppressing vibration during traveling.

Background Art

[0002] Among wheel-type construction machines such as wheel-type hydraulic excavators and wheel loaders, there are known ones that use an accumulator to suppress vibration during traveling (see, for example, Patent Document 1). In the traveling vibration damping hydraulic circuit of the wheeled construction machine described in Patent Document 1, a vibration damping accumulator is connected via an on-off valve to the bottom side of a hydraulic cylinder that drives a working device composed of a boom, a bucket, etc., and the head side of the hydraulic cylinder is connected to an oil tank via another on-off valve. When the changeover switch is operated to the on state by the operator during traveling and the vehicle speed becomes a predetermined vehicle speed or higher, the on-off valve is switched to the open state, so that the accumulator communicates with the bottom side of the hydraulic cylinder and the head side of the hydraulic cylinder communicates with the oil tank. Thereby, even when the wheeled construction machine (wheel-type construction machine) vibrates up and down due to traveling, the energy of the up and down vibration of the working device is absorbed by the accumulator and attenuated, so that the up and down vibration during traveling is damped.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in wheeled construction machinery, when moving from a work site to a public road, the wheels are sometimes spun freely while the machine is jacked up with the work equipment on the ground to remove mud and other debris adhering to the tires. However, in the technology described in Patent Document 1, if the changeover switch for driving vibration damping is already turned ON when moving from the work site (when driving begins), the function that dampens driving vibrations (driving vibration damping function) may switch to the activated state (on / off valve open) when the rotational speed of the free-spinning wheels reaches a predetermined level. In this case, the head side of the hydraulic cylinder is in communication with the oil tank, so the pressurized oil on the head side of the hydraulic cylinder escapes into the oil tank, and it may become impossible to maintain the jacked-up state. For this reason, in order to prevent pressurized oil from flowing from the head side of the hydraulic cylinder into the oil tank during jacking up, it is necessary to switch the changeover switch for driving vibration damping to OFF before jacking up. Furthermore, when starting to drive again and moving onto a public road after jacking up the vehicle, the vibration damping function cannot be activated unless the switch is switched back to the ON position. Thus, the operator needs to individually switch the switch for the vibration damping function according to various situations.

[0005] This invention was made to solve the above-mentioned problems, and its purpose is to provide a wheeled construction machine that can reduce the hassle of operating the changeover switch for the driving vibration suppression function. [Means for solving the problem]

[0006] The present invention includes several means for solving the above problem, but to give one example, a wheeled construction machine comprising a self-propelled vehicle body to which wheels are attached, a work device attached to the vehicle body, a control device that controls the flow of pressurized oil from a hydraulic cylinder that drives the work device and executes control of a vibration suppression function that suppresses vibration of the hydraulic cylinder when the rotational speed of the wheels reaches a predetermined level, and a vibration suppression instruction device that indicates whether the control of the vibration suppression function by the control device is enabled or disabled,A hydraulic pump that supplies pressurized oil to the hydraulic cylinder; an accumulator provided in the hydraulic line between the hydraulic pump and the hydraulic cylinder to absorb pressure fluctuations in the hydraulic cylinder; and a switching valve device that can switch between a first state in which pressurized oil flows from the hydraulic cylinder to the accumulator and from the hydraulic cylinder to the tank to activate the vibration suppression function, and a second state in which pressurized oil flows from the hydraulic cylinder to the accumulator and from the hydraulic cylinder to the tank to stop the vibration suppression function. The accumulator further comprises: an operating device that outputs operating instructions for the work device; a pressure sensor that detects the pressure of the hydraulic cylinder; an operation detector that detects the operating instructions from the operating device; a speed sensor that detects the rotational speed of the wheel; a hose rupture valve installed in the hydraulic line and having the function of preventing pressurized oil from flowing from the hydraulic cylinder to the hydraulic line when the hydraulic line ruptures; and a release valve that can be switched to either maintain or release the function of the hose rupture valve, wherein the accumulator is connected to the hydraulic cylinder via the hose rupture valve. The control device disables the vibration suppression function when the vehicle body is jacked up by the work device, even if the vibration suppression instruction device has indicated that the vibration suppression function is enabled. Furthermore, if the vibration suppression instruction device instructs that the vibration suppression function be enabled, the switching valve device is controlled to the first state or the second state based on the detected value of the pressure sensor, the detected value of the operation detector, and the detected value of the speed sensor. When the switching valve device is controlled to the first state, the release valve is controlled so that the function of the hose rupture valve is released. When the switching valve device is controlled to the second state, the release valve is controlled so that the function of the hose rupture valve is maintained. It is characterized by the following: [Effects of the Invention]

[0007] According to the present invention, even when the vibration suppression instruction device has indicated that the vibration suppression function control is enabled, the vibration suppression function control is disabled when the vehicle body is jacked up by the work device. Therefore, the operator does not need to perform any operation to instruct the vibration suppression instruction device to disable the vibration suppression function control. In other words, the hassle of operating the vibration suppression instruction device can be reduced. Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing a wheeled hydraulic excavator, which is a first embodiment of the wheeled construction machine of the present invention, in a partially transparent state. [Figure 2] This figure shows the equipment inside the cab of a wheeled construction machine according to the first embodiment shown in Figure 1. [Figure 3] Figure 1 is a block diagram showing the schematic configuration of the hydraulic system and the travel system in a wheeled construction machine according to the first embodiment. [Figure 4] Figure 1 is a block diagram showing the functions of the control device in a wheeled construction machine according to the first embodiment. [Figure 5] Figure 4 is an explanatory diagram showing a lifting operation when the control device of the wheeled construction machine according to the first embodiment performs overload warning control. [Figure 6] Figure 4 is a flowchart showing an example of the processing procedure for ride control in the control device of a wheeled construction machine according to the first embodiment. [Figure 7] This figure illustrates the jack-up operation in a wheeled construction machine according to the first embodiment shown in Figure 1. [Figure 8] This is a circuit diagram showing the schematic configuration of the hydraulic system and a block diagram showing the schematic configuration of the travel system in a wheeled construction machine according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the wheeled construction machine of the present invention will be described with reference to the drawings. In this description, a wheeled hydraulic excavator will be used as an example of an embodiment of the wheeled construction machine of the present invention.

[0010] [First Embodiment] First, the configuration of a wheeled hydraulic excavator as a first embodiment of the wheeled construction machine of the present invention will be described using Figures 1 and 2. Figure 1 is a perspective view showing a wheeled hydraulic excavator as a first embodiment of the wheeled construction machine of the present invention in a partially transparent state. Figure 2 is a diagram showing the equipment inside the cab of the wheeled construction machine according to the first embodiment shown in Figure 1.

[0011] In Figure 1, the wheeled hydraulic excavator 1 (hereinafter referred to as hydraulic excavator 1) comprises a self-propelled wheeled vehicle body 2, a slewing body 3 mounted on the vehicle body 2 so as to be rotatable, and a front working device 4 mounted on the front of the slewing body 3 so as to be vertically movable (up and down). The hydraulic excavator 1 can perform excavation work etc. at the work site using the front working device 4, and can move from the work site to public roads using the wheeled vehicle body 2. The hydraulic excavator 1 can also be configured with a soil removal blade 5 attached to the rear end of the vehicle body 2 (see Figure 7 below). The soil removal blade 5 is used for soil removal and leveling. The hydraulic excavator 1 can perform the jack-up operation described below by using the front working device 4 and the soil removal blade 5.

[0012] The vehicle body 2 comprises a frame 11 extending in the front-rear direction, left and right front wheels 13 (only the left side is shown) attached to the front of the frame 11 via an axle 12, and left and right rear wheels 15 attached to the rear of the frame 11 via an axle 14. The frame 11 is equipped with a hydraulic motor 17 and a transmission 18.

[0013] Axles 12 and 14 rotatably support the front wheels 13 and rear wheels 15, respectively, and transmit the rotational driving force of the hydraulic motor 17 to the front wheels 13 and rear wheels 15. They also include a differential mechanism that distributes the rotational driving force to the left and right wheels. Axles 12 and 14 are pivotably mounted to the frame 11. That is, axles 12 and 14 are configured to pivot relative to the slewing body 3, which is the vehicle body. It is also possible to configure the system so that the rotational driving force of the hydraulic motor 17 is transmitted to only one of the front wheels 13 or the rear wheels 15. Furthermore, it is also possible to configure the system so that only one of axles 12 or 14 is pivotably mounted to the frame 11, while the other is fixed.

[0014] The revolving body 3 is configured to be revolved and driven with respect to the frame 11 of the traveling body 2 by a revolving hydraulic motor 6. The revolving body 3 includes a cab 21 on which an operator rides, a machine room 22 that houses various devices, and a counterweight 23 for balancing with the front working device 4. As shown in FIG. 2, in the cab 21, there are arranged a driver's seat 25 on which the operator sits, an operation device 26 that outputs operation instructions for the front working device 4 and the like, an accelerator pedal 27, a brake pedal 28, a steering 29 for operating the traveling of the traveling body 2, and the like. The operation device 26 is, for example, an operation lever device that instructs the operation of the front working device 4 according to lever operations, and has a left operation lever 26a and a right operation lever 26b. Operations of a boom 41, an arm 42, and a bucket 43, which will be described later and constitute the front working device 4, are assigned to the left operation lever 26a and the right operation lever 26b. The steering 29 steers the front wheels 13. In the cab 21, there are arranged a ride control switch 31 (hereinafter referred to as an RC switch), an overload warning switch 32, and a monitor 33 (also refer to FIG. 4), which will be described later. In the machine room 22, as shown in FIG. 1 for example, an engine 35 as a prime mover, a hydraulic pump 51, a control valve unit 53, a hydraulic oil tank 57, and the like are housed.

[0015] The front working device 4 is an articulated working device for performing excavation work and the like, and includes, for example, a boom 41, an arm 42, and a bucket 43 as an attachment. The boom 41 is rotatably connected to the front part of the revolving body 3. The arm 42 is rotatably connected to the tip of the boom 41. The bucket 43 is rotatably connected to the tip of the arm 42. The boom 41, the arm 42, and the bucket 43 are respectively driven by a boom cylinder 45, an arm cylinder 46, and a bucket cylinder 47, which are hydraulic actuators.

[0016] Next, the configurations of the hydraulic system and the traveling system in the first embodiment of the wheel-type construction machine of the present invention will be described with reference to FIG. 3. FIG. 3 is a circuit diagram showing the schematic configuration of the hydraulic system and a block diagram showing the schematic configuration of the traveling system in the wheel-type construction machine according to the first embodiment shown in FIG. 1.

[0017] In FIG. 3, the hydraulic system of the hydraulic excavator 1 includes a hydraulic pump 51 that is driven by an engine 35 as a prime mover to discharge pressure oil, a plurality of hydraulic actuators that are driven by the pressure oil supplied from the hydraulic pump 51, and a control valve unit 53 that is an assembly of control valves for controlling the flow (direction and flow rate) of the pressure oil supplied from the hydraulic pump 51 to each of the plurality of hydraulic actuators.

[0018] In FIG. 3, only the traveling hydraulic motor 17 that is driven during traveling and the boom cylinder 45 related to ride control are shown as hydraulic actuators. The hydraulic circuits of the other hydraulic actuators (such as the swing hydraulic motor 6, the arm cylinder 46, and the bucket cylinder 47) are omitted.

[0019] The boom cylinder 45 has a cylinder body 45a, a piston 45b slidably disposed in the cylinder body 45a, and a piston rod 45c extending from one side of the piston 45b. The inside of the cylinder body 45a is partitioned into a first oil chamber Cb and a second oil chamber Cr by the piston 45b. The first oil chamber Cb is an oil chamber to which pressure oil from the hydraulic pump 51 is supplied when driving the boom 41 (front working device 4) upward. On the other hand, the second oil chamber Cr is an oil chamber to which pressure oil from the hydraulic pump 51 is supplied when driving the boom 41 (front working device 4) downward. That is, when pressure oil is supplied to the first oil chamber Cb, the boom cylinder 45 extends to drive the boom 41 upward. On the other hand, when pressure oil is supplied to the second oil chamber Cr, the boom cylinder 45 contracts to drive the boom 41 downward. The weight of the boom 41 (front working device 4) acts on the first oil chamber Cb. Hereinafter, the first oil chamber Cb and the second oil chamber Cr are referred to as the bottom chamber and the rod chamber, respectively.

[0020] The control valve unit 53 is connected to the bottom chamber Cb side of the boom cylinder 45 via the first actuator line 54 and the hose rupture valve 56 (hereinafter referred to as the HR valve), and is also connected to the rod chamber Cr side of the boom cylinder 45 via the second actuator line 55. The first actuator line 54 is a hydraulic line that guides pressurized oil from the hydraulic pump 51 to the bottom chamber Cb of the boom cylinder 45 via the control valve unit 53. The second actuator line 55 is a hydraulic line that guides pressurized oil from the hydraulic pump 51 to the rod chamber Cr of the boom cylinder 45 via the control valve unit 53.

[0021] The HR valve 56 is installed between the bottom chamber Cb of the boom cylinder 45 and the first actuator line 54, and has the function of preventing pressurized oil from flowing out of the bottom chamber Cb of the boom cylinder 45 to the first actuator line 54 when the first actuator line 54 ruptures. This prevents the boom 41 from falling when the first actuator line 54 ruptures. The HR valve 56 has a poppet valve 81 that prevents pressurized oil from flowing out of the bottom chamber Cb of the boom cylinder 45 when the first actuator line 54 ruptures, a pilot valve 82 that drives the poppet valve 81, and a small relief valve 83 that has an overload relief function. The HR valve 56 has the poppet valve 81, pilot valve 82, and small relief valve 83 built into the housing 84.

[0022] The poppet valve 81 has a valve body 85 slidably disposed within a housing 84. The poppet valve 81 has a piping connection chamber 86 connected to a first actuator line 54, a cylinder connection chamber 87 connected to the bottom chamber Cb of the boom cylinder 45, and a back pressure chamber 88 located on the opposite side of the piping connection chamber 86, with the valve body 85 in between. The valve body 85 is provided with a throttling passage 85a that connects the cylinder connection chamber 87 and the back pressure chamber 88. The poppet valve 81 is configured such that the valve body 85 moves in accordance with the balance between the force acting due to the pressure in the piping connection chamber 86 and the cylinder connection chamber 87 and the force acting due to the pressure in the back pressure chamber 88 and the biasing force of the spring 89, thereby switching the communication between the piping connection chamber 86 and the cylinder connection chamber 87 or blocking it.

[0023] The piping connection chamber 86 and back pressure chamber 88 of the poppet valve 81 are connected via a first connection passage 91, a pilot valve 82, and a second connection passage 92. The piping connection chamber 86 and cylinder connection chamber 87 of the poppet valve 81 are connected via a first connection passage 91, a pilot valve 82, and a third connection passage 93. The cylinder connection chamber 87 of the poppet valve 81 (bottom chamber Cb of the boom cylinder 45) is connected via a relief passage 94 to a hydraulic oil tank 57 that stores hydraulic oil.

[0024] The pilot valve 82 has a pressure-receiving section 82a to which the release pilot pressure described later is directed, and by displacing in accordance with the release pilot pressure directed to the pressure-receiving section 82a, it switches between opening or closing the communication between the first connection passage 91 and the second connection passage 92, and between opening or closing the communication between the first connection passage 91 and the third connection passage 93. In other words, the pilot valve 82 controls the opening and closing of the poppet valve 81 by opening or closing the communication between the first connection passage 91 and the second connection passage 92, and controls the discharge of pressurized oil from the bottom chamber Cb of the boom cylinder 45 to the control valve unit 53 without going through the poppet valve 81 by opening or closing the communication between the first connection passage 91 and the third connection passage 93. The pilot valve 82 is normally configured to be in the closed position.

[0025] The small relief valve 83 is located on the relief passage 94 and is configured to open when the relief passage 94 (cylinder connection chamber 87) exceeds a set pressure. In the HR valve 56, when the small relief valve 83 opens, the pilot valve 82 is driven to open the poppet valve 81.

[0026] The hydraulic system further includes a configuration that enables ride control to suppress vibrations during the travel of the hydraulic excavator 1 (when the rotational speed of the wheels 13 and 15 reaches a predetermined level). Specifically, it includes an accumulator 58 for ride control. The accumulator 58 absorbs pressure fluctuations in the bottom chamber Cb of the boom cylinder 45 and is connected to the first actuator line 54 via, for example, a first ride control valve 59 (hereinafter referred to as the first RC valve). That is, the accumulator 58 is connected to the bottom chamber Cb of the boom cylinder 45 via the first RC valve 59 and the HR valve 56. The accumulator 58 and the first actuator line 54 are connected via a first connection line 60, on which the first RC valve 59 is provided.

[0027] The first RC valve 59 controls the flow of pressurized oil between the accumulator 58 and the bottom chamber Cb of the boom cylinder 45 (the flow of pressurized oil in the first connection line 60), thereby switching the vibration suppression function (i.e., ride control that suppresses vibrations during travel) which absorbs pressure fluctuations in the bottom chamber Cb of the boom cylinder 45 using the accumulator 58, between an activated state and a deactivated state. The first RC valve 59 is configured to be switchable between, for example, a first position S that allows the flow of pressurized oil from the accumulator 58 to the bottom chamber Cb of the boom cylinder 45 while blocking the flow of pressurized oil from the bottom chamber Cb of the boom cylinder 45 to the accumulator 58, and a second position R that allows bidirectional flow of pressurized oil between the accumulator 58 and the bottom chamber Cb of the boom cylinder 45. The first position S is a position that deactivates the ride control by making it impossible to exchange pressurized oil between the accumulator 58 and the bottom chamber Cb of the boom cylinder 45. On the other hand, the second position R is the position in which the ride control is activated by creating a communication between the accumulator 58 and the bottom chamber Cb of the boom cylinder 45, enabling the exchange of pressurized oil. The first RC valve 59 is a solenoid valve configured to switch to the first position S (the stop position of the ride control) under normal circumstances. The first RC valve 59 is configured to switch in response to a command from the control device 100, which will be described later.

[0028] Furthermore, the accumulator 58 is connected to the hydraulic fluid tank 57 via a ride control relief valve 61. A relief line 62 is connected to the portion of the first connection line 60 between the accumulator 58 and the first RC valve 59, and the ride control relief valve 61 is provided on the relief line 62. The ride control relief valve 61 defines the upper limit of the accumulated pressure of the accumulator 58 and is configured to open when the relief line 62 (accumulator 58) exceeds the set pressure.

[0029] In the hydraulic system, to achieve ride control, the rod chamber Cr of the boom cylinder 45 is connected to the hydraulic fluid tank 57 via a second ride control valve 63 (hereinafter referred to as the second RC valve). Specifically, the hydraulic fluid tank 57 is connected to the second actuator line 55 via a second connection line 64, and the second RC valve 63 is provided on the second connection line 64.

[0030] The second RC valve 63 controls the flow of hydraulic fluid (the flow of pressurized oil in the second connection line 64) between the rod chamber Cr of the boom cylinder 45 and the hydraulic fluid tank 57, thereby switching the vibration suppression function (ride control) of the accumulator 58 between an activated and deactivated state. The second RC valve 63 is configured to be switchable between, for example, a first position S that allows the flow of hydraulic fluid from the hydraulic fluid tank 57 to the rod chamber Cr of the boom cylinder 45 while blocking the flow of hydraulic fluid from the rod chamber Cr of the boom cylinder 45 to the hydraulic fluid tank 57, and a second position R that allows bidirectional pressurized oil flow between the rod chamber Cr of the boom cylinder 45 and the hydraulic fluid tank 57. That is, the first position S is the position that deactivates the ride control by preventing the outflow of hydraulic fluid from the rod chamber Cr of the boom cylinder 45. On the other hand, the second position R is the position that activates the ride control by enabling the exchange of hydraulic fluid by creating a communication between the rod chamber Cr of the boom cylinder 45 and the hydraulic fluid tank 57. The second RC valve 63 is a solenoid valve configured to switch to the first position S (the stop position of the ride control) under normal circumstances. The second RC valve 63 is configured to switch in response to a command from the control device 100, which will be described later.

[0031] In this embodiment, the first RC valve 59 and the second RC valve 63 are configured as switching valve devices that control the flow of pressurized oil between the bottom chamber Cb of the boom cylinder 45 and the accumulator 58, and also control the flow of pressurized oil between the rod chamber Cr of the boom cylinder 45 and the hydraulic oil tank 57, thereby switching the vibration suppression function, which absorbs pressure fluctuations in the bottom chamber Cb of the boom cylinder 45 using the accumulator 58, between an activated state and a deactivated state.

[0032] In other words, the hydraulic excavator 1 includes a self-propelled vehicle body (traveling body 2 and slewing body 3) to which wheels (front wheels 13 and rear wheels 15) are attached, a work device (e.g., boom 41, arm 42, bucket 43) attached to the vehicle body, and a vibration suppression function that suppresses vibrations of the hydraulic cylinder (e.g., boom cylinder 45) that drives the work device when the rotational speed of the wheels (front wheels 13 and rear wheels 15) reaches a predetermined level.

[0033] Furthermore, the hydraulic excavator 1 includes a hydraulic pump (hydraulic pump 51) that supplies pressurized oil to the hydraulic cylinders (e.g., boom cylinder 45, arm cylinder 46, bucket cylinder 47) that drive the work device, an accumulator (accumulator 58) provided in the hydraulic line (first actuator line 54) between the hydraulic pump (hydraulic pump 51) and the hydraulic cylinder (e.g., boom cylinder 45) to absorb pressure fluctuations in the hydraulic cylinder (e.g., boom cylinder 45), and the accumulator (accumulator 58) that absorbs pressure fluctuations in the hydraulic cylinder (e.g., boom cylinder 45). The system includes a switching valve device (for example, a first RC valve 59 and a second RC valve 63) that can switch between a first state in which pressurized oil is allowed to flow to 8) and from the hydraulic cylinder (for example, boom cylinder 45) to the tank (tank 57) to activate the vibration suppression function, and a second state in which pressurized oil is blocked from flowing from the hydraulic cylinder (for example, boom cylinder 45) to the accumulator (accumulator 58) and from flowing from the hydraulic cylinder (for example, boom cylinder 45) to the tank (tank 57) to stop the vibration suppression function.

[0034] The hydraulic system further includes a pilot hydraulic circuit that drives each control valve of the control valve unit 53 and deactivates the function of the HR valve 56. The pilot hydraulic circuit includes a pilot pump 71 driven by the engine 35 as the prime mover, an operating device 26 (see also Figure 2) that uses the discharge pressure of the pilot pump 71 as the source pressure to generate an operating pilot pressure for driving the control valves of the control valve unit 53 and a deactivation pilot pressure used to deactivate the function of the HR valve 56, an HRV deactivation valve 73 that outputs the discharge pressure of the pilot pump 71 as a deactivation pilot pressure used to deactivate the function of the HR valve 56 without going through the operating device 26, and a shuttle valve 74 that selects the higher-pressure deactivation pilot pressure from the deactivation pilot pressure output from the operating device 26 and the deactivation pilot pressure output from the HRV deactivation valve 73 and outputs it to the HR valve 56.

[0035] The operating device 26 is connected to one input port of the shuttle valve 74 via the first pilot line 75. However, the first pilot line 75 is used only for boom lowering operations. The HRV release valve 73 is connected to the pilot pump 71 and the other input port of the shuttle valve 74 via the second pilot line 76. The output port of the shuttle valve 74 is connected to the pressure receiving section 82a of the pilot valve 82 of the HR valve 56. Note that in Figure 3, the hydraulic circuit showing the input of operating pilot pressure from the operating device 26 to the control valve unit 53 is omitted.

[0036] The HRV release valve 73 is configured to be selectively switchable between a first position N, which disconnects the connection between the pilot pump 71 and the shuttle valve 74, and a second position C, which connects the pilot pump 71 and the shuttle valve 74, allowing switching between maintaining or releasing the function of the HR valve 56. The first position N is the position in which the function of the HR valve 56 is maintained (the function is not forcibly released) without outputting a release pilot pressure to the pilot valve 82 (shuttle valve 74) of the HR valve 56. The second position C is the position in which the function of the HR valve 56 is forcibly released by outputting a release pilot pressure to the pilot valve 82 (shuttle valve 74) of the HR valve 56. The HRV release valve 73 is, for example, a solenoid valve configured to be in the first position N under normal circumstances. The HRV release valve 73 is configured to be switchable in response to a command from the control device 100 described later.

[0037] The HR valve 56 is equipped with a first pressure sensor 96 that detects the pressure in the cylinder connection chamber 87. Specifically, the first pressure sensor 96 detects the pressure in the bottom chamber Cb of the boom cylinder 45 (hereinafter sometimes referred to as bottom pressure). The first pressure sensor 96 outputs a detection signal corresponding to the detected value to the control device 100, which will be described later.

[0038] A second pressure sensor 97 is provided in the first pilot line 75. The second pressure sensor 97 detects the operating pilot pressure of the control valve unit 53 generated by the operating device 26 and functions as an operation detector that detects operation instructions from the operating device 26. The second pressure sensor 97 outputs a detection signal corresponding to the detected value to the control device 100, which will be described later.

[0039] A third pressure sensor 98 is provided on the second pilot line 76. The third pressure sensor 98 detects the release pilot pressure output by the HRV release valve 73 and is used as information to determine whether or not the HRV release valve 73 is malfunctioning. The third pressure sensor 98 outputs a detection signal corresponding to the detected value to the control device 100, which will be described later.

[0040] In the travel system of the hydraulic excavator 1, the travel hydraulic motor 17 is driven by pressurized oil supplied from the hydraulic pump 51 via the control valve unit 53. The rotational power of the travel hydraulic motor 17 is transmitted to the front wheels 13 and rear wheels 15 (wheels) via power transmission mechanisms such as the transmission 18 and axles 12 and 14. The transmission 18 transmits the rotational power of the travel hydraulic motor 17 to the front wheels 13 and rear wheels 15 after shifting the speed. The transmission 18 is equipped with a speed sensor 99 that detects the rotational speed (rotational speed) of the wheels 13 and 15. The travel speed of the hydraulic excavator 1 (vehicle body 2 and 3) is calculated based on the rotational speed (rotational speed) of the wheels 13 and 15, which are detected by the speed sensor 99. The speed sensor 99 outputs a detection signal corresponding to the detected rotational speed (rotational speed) to the control device 100, which will be described later.

[0041] In the hydraulic excavator 1, axles 12 and 14 are pivotably mounted to the frame 11, and a pair of ram cylinders 66 (only one shown) are interposed between the axles 12 and 14 and the frame 11. Each ram cylinder 66 has a rod 66a, which extends and retracts in response to the oscillation of the axles 12 and 14, functioning as a shock absorber to absorb vibrations from the frame 11. The hydraulic excavator 1 is equipped with a locking mechanism that prevents the axles 12 and 14 from swinging relative to the frame 11 by locking the extension and retraction of the rods 66a of the ram cylinders 66.

[0042] Specifically, as a locking mechanism, each ram cylinder 66 is connected to the hydraulic fluid tank 57 via a pilot check valve 67. The pilot check valve 67 is configured to allow the flow of hydraulic fluid from the hydraulic fluid tank 57 to the ram cylinder 66, while blocking the flow of hydraulic fluid from the ram cylinder 66 to the hydraulic fluid tank 57. The pilot port of the pilot check valve 67 is configured to be selectively connected to either the pilot pump 71 or the hydraulic fluid tank 57 via an axle lock valve 78.

[0043] The axle lock valve 78 is configured to be selectively switchable between a first position L, in which the pilot port of the pilot check valve 67 is connected to the hydraulic oil tank 57, and a second position C, in which the pilot port of the pilot check valve 67 is connected to the pilot pump 71. The first position L is the lock position, which activates the axle lock that prevents the axles 12 and 14 from swinging relative to the frame 11. The second position C is the release position, which releases the axle lock.

[0044] When the axle lock valve 78 is in the first position L, the pilot check valve 67 functions as a check valve, preventing the outflow of hydraulic fluid from the ram cylinder 66. This prevents the ram cylinder 66 from extending or retracting, resulting in an axle lock state (locked state) where the axles 12 and 14 cannot swing. When the axle lock valve 78 is in the second position C, the pilot check valve 67 functions as an opening valve, allowing the ram cylinder 66 and the hydraulic fluid tank 57 to communicate and permitting bidirectional flow of hydraulic fluid. This allows the ram cylinder 66 to extend or retract, and as the ram cylinder 66 extends or retracts in accordance with the swing of the axles 12 and 14, it absorbs vibrations on the frame 11 side. In other words, the axle lock state (released state) is achieved. The axle lock valve 78 is, for example, a solenoid valve configured to be in the first position L under normal circumstances. The axle lock valve 78 is configured to be switched in response to commands from the control device 100, which will be described later.

[0045] Next, the hardware configuration and functional configuration of the control device in the first embodiment of the wheeled construction machine of the present invention will be described with reference to Figures 4 and 5. Figure 4 is a block diagram showing the functions of the control device in the wheeled construction machine according to the first embodiment shown in Figure 1. Figure 5 is an explanatory diagram showing a lifting operation when the control device of the wheeled construction machine according to the first embodiment shown in Figure 4 performs overload warning control.

[0046] In general terms, the control device 100 of this embodiment is configured to perform axle lock switching control to prevent the axles 12 and 14 from swinging relative to the frame 11, and to perform overload warning control to issue a warning when the load of the lifting operation by the front work device 4 is excessive. In addition, the control device 100 is configured to perform ride control (vibration suppression function) to suppress vibration of the boom cylinder 45 when the vehicle body 2 and 3 is traveling (when the rotational speed of the wheels 13 and 15 reaches a predetermined level) by controlling the flow of pressurized oil from the boom cylinder 45.

[0047] Specifically, the control device 100 is electrically connected to an overload alarm switch 32 and an RC switch 31. The overload alarm switch 32 is an indicator device that instructs the operator to perform the overload alarm control described above, and outputs an ON signal to the control device 100 indicating an instruction for overload alarm control or an OFF signal indicating no instruction for overload alarm control. The RC switch 31 is a vibration suppression indicator device that instructs the operator to enable or disable the ride control (vibration suppression function) by the control device 100, and outputs an ON signal to the control device 100 indicating an instruction to enable the ride control (vibration suppression function) by the control device 100 or an OFF signal indicating an instruction to disable the ride control (vibration suppression function) by the control device 100.

[0048] The control device 100 is also electrically connected to a first pressure sensor 96, a second pressure sensor 97, and a third pressure sensor 98. The detected values ​​Pb (boom bottom pressure) from the first pressure sensor 96, Pp (operating pilot pressure of the operating device 26) from the second pressure sensor 97, and Pc (release pilot pressure of the HRV release valve 73) from the third pressure sensor 98 are input as detection signals. In addition, a speed sensor 99 is electrically connected to the control device 100, and the detected value V (rotational speed of wheels 13 and 15) from the speed sensor 99 is input as a detection signal. The control device 100 converts the detected value V from the speed sensor 99 into the travel speed Vt of the hydraulic excavator 1 (vehicle body 2 and 3).

[0049] The control device 100 includes, for example, a storage device 101 consisting of RAM or ROM, and a processing device 102 such as a CPU or MPU. The storage device 101 has programs and information necessary for various controls such as the axle lock switching control, overload alarm control, and ride control stored in advance. The storage device 101 can also be configured to include a magnetic storage device such as a hard disk drive instead of or in addition to the semiconductor memory of ROM and RAM. The processing device 102 reads various programs and information from the storage device 101 as appropriate and executes processing according to the programs to realize various functions, including the following functional units.

[0050] The control device 100 includes an axle lock control unit 111, an overload alarm control unit 112, and a ride control unit 113.

[0051] The axle lock control unit 111 controls the axle lock, which prevents the axles 12 and 14 from swinging by allowing or blocking the extension and retraction of the ram cylinder 66 through the switching of the axle lock valve 78 shown in Figure 3. When the axle lock is set to the locked state, a command is output to the axle lock valve 78 to switch to the first position L (locked position). On the other hand, when the axle lock is set to the released state, a command is output to the axle lock valve 78 to switch to the second position C (released position). The axle lock control unit 111 holds information on the switching position of the axle lock valve 78 (i.e., information on whether the lock mechanism is in the locked state or the released state). For example, it is possible to obtain a signal from the axle lock valve 78.

[0052] The overload alarm control unit 112 performs overload alarm control, issuing an alarm when the load of the suspended load W is excessively high during the execution of a suspension operation (crane operation) by the front work device 4 as shown in Figure 5. Specifically, when an ON signal is input to the overload alarm switch 32, it calculates the actual load of the suspended load W and determines whether the calculated actual load exceeds the rated load. If the determination result is that it exceeds the rated load, it outputs an alarm command to the monitor 33, which acts as an alarm device, for example.

[0053] The ride control unit 113 controls the first RC valve 59 and the second RC valve 63, which act as switching valve devices, and also controls the HRV release valve 73, thereby switching the ride control between an activated state and a deactivated state.

[0054] When an off signal (an instruction to disable ride control by the control device 100) is input from the RC switch 31, the first RC valve 59 and the second RC valve 63, which act as switching valve devices, are controlled so that the ride control is stopped, and the HRV release valve 73 is controlled so that the function of the HR valve 56 is maintained. Specifically, a command (e.g., an off signal) is output to the first RC valve 59 and the second RC valve 63 to switch to the first position S (a position that blocks the flow from the boom cylinder 45 to the accumulator 58 and the hydraulic oil tank 57). In addition, a command (e.g., an off signal) is output to the HRV release valve 73 to switch to the first position N (a position that blocks the output of release pilot pressure to the HR valve 56).

[0055] When an ON signal (an instruction from the control device 100 to enable ride control) is received from the RC switch 31, the ride control unit 113 determines whether or not to activate the ride control based on the presence or absence of an overload alarm control instruction from the overload alarm switch 32 (ON signal or OFF signal) and the state of the lock mechanism (locked or unlocked state of the axle lock). Furthermore, it determines whether or not to activate the ride control based on three execution conditions: the detected value from the first pressure sensor 96 (boom bottom pressure Pb), the detected value from the second pressure sensor 97 (operating pilot pressure Pp of the control valve unit 53), and the detected value from the speed sensor 99 (rotation speed V of the wheels 13 and 15). The first RC valve 59, the second RC valve 63, and the HRV release valve 73 are controlled according to these determination results. When switching the ride control to the activated state, a command (e.g., an excitation current) is output to the first RC valve 59 and the second RC valve 63 to switch to the second position R (a position that allows bidirectional flow between the bottom chamber Cb of the boom cylinder 45 and the accumulator 58). In addition, a command (e.g., an excitation current) is output to the HRV release valve 73 to switch to the second position C (a position that outputs the release pilot pressure to the HR valve 56).

[0056] If the HRV release valve 73 is malfunctioning, the ride control will be stopped. Whether or not the HRV release valve 73 is malfunctioning is determined by the value detected by the third pressure sensor 98 (the release pilot pressure output by the HRV release valve 73).

[0057] Next, the processing procedure of the ride control unit of the control device in the first embodiment of the wheeled construction machine of the present invention will be described with reference to Figures 6 and 7. Figure 6 is a flowchart showing an example of the processing procedure of the ride control in the control device of the wheeled construction machine according to the first embodiment shown in Figure 4. Figure 7 is a diagram illustrating the jack-up operation in the wheeled construction machine according to the first embodiment shown in Figure 1.

[0058] In Figure 6, the ride control unit 113 of the control device 100 (see Figure 4) determines whether the instruction signal from the RC switch 31 is an ON signal (an instruction to enable ride control by the control device 100) (step S10). If the instruction signal from the RC switch 31 is an ON signal (YES), the process proceeds to step S20. If the instruction signal from the RC switch 31 is an OFF signal (an instruction to disable ride control by the control device 100) (NO), the process proceeds to step S90.

[0059] If NO is determined in step S10, the ride control unit 113 switches the ride control to the stopped state (step S90). Specifically, it outputs a command to the first RC valve 59 and the second RC valve 63 (switching valve device) to switch to the first position N (second state). This prevents the flow from the bottom chamber Cb of the boom cylinder 45 to the accumulator 58, and also prevents the flow from the rod chamber Cr of the boom cylinder 45 to the hydraulic oil tank 57. In addition, it controls the HRV release valve 73 so that the function of the HR valve 56 is maintained. Specifically, it outputs a command to the HRV release valve 73 shown in Figure 3 to switch to the first position N.

[0060] On the other hand, if the result in step S10 is YES, it is determined in step S20 whether the instruction signal from the overload alarm switch 32 is an ON signal (i.e., whether there is an instruction for overload alarm control). If the instruction signal from the overload alarm switch 32 is an OFF signal (i.e., NO, no instruction for overload alarm control), the process proceeds to step S30. However, if the instruction signal from the overload alarm switch 32 is an ON signal (i.e., YES), the process proceeds to step S90, which switches the ride control to the stopped state.

[0061] If the result in step S20 is NO, the ride control unit 113 determines whether the axle lock (locking mechanism) is in the locked state (step S30). If the axle lock is in the locked state (YES), the process proceeds to step S90, which switches the ride control to the stopped state. If the axle lock is in the released state (NO), the process proceeds to step S40. The state of the axle lock (locking mechanism) (locked or released) is determined, for example, based on the switching position information of the axle lock valve 78 of the axle lock control unit 111. That is, if the switching position information of the axle lock valve 78 is the first position L, the axle lock is determined to be in the locked state. On the other hand, if the switching position information is the second position C, the axle lock is determined to be in the released state.

[0062] If the result in step S30 is NO, the ride control unit 113 determines whether the ride control is in a stopped state (step S40). If the ride control is in a stopped state (YES), the process proceeds to step S50; if the ride control is in operation (NO), the process proceeds to step S110. The state of the ride control (stopped or operating) is determined, for example, based on the switching position information of the first RC valve 59 and the second RC valve 63. That is, if the switching position information of the first RC valve 59 and the second RC valve 63 is the first position S, the ride control is determined to be in a stopped state. On the other hand, if the switching position information is the second position R, the ride control is determined to be in an operating state.

[0063] If the result in step S40 is YES, the ride control unit 113 determines whether the pressure in the bottom chamber Cb of the boom cylinder 45 (boom bottom pressure Pb), which is the value detected by the first pressure sensor 96, satisfies the conditions for executing the ride control (step S50). If the boom bottom pressure Pb satisfies the conditions (if YES), the process proceeds to step S60; however, if the conditions are not met (if NO), the process proceeds to step S90, which switches the ride control to the stopped state.

[0064] Specifically, when the boom bottom pressure Pb, which is the detected value of the first pressure sensor 96, is greater than the first threshold value P1 and less than the second threshold value P2 (when P1 < Pb < P2), it is determined that the first execution condition of the ride control is satisfied (YES). Otherwise, it is determined that the first execution condition of the ride control is not satisfied (NO). The first threshold value P1 is, for example, the lower limit value of the boom bottom pressure required to hold the front working device 4 in the air. The second threshold value P2 is set, for example, to be not more than the set pressure of the ride control relief valve 61.

[0065] The condition Pb > P1 is a determination condition as to whether the hydraulic excavator 1 is in the jack-up operation. The jack-up operation is an operation of lifting the running body 2 and the slewing body 3 by grounding the bucket 43 (attachment) of the front working device 4 or the earthmoving blade 5, as shown in FIG. 7 for example. During the jack-up operation, the pressure in the rod chamber Cr of the boom cylinder 45 becomes high, while the pressure in the bottom chamber Cb (boom bottom pressure Pb) becomes low. From this, when the boom bottom pressure Pb is not more than the first threshold value P1, there is a possibility of being in the jack-up operation, and it is determined that the first execution condition of the ride control is not satisfied.

[0066] The condition Pb < P2 is a determination condition for preventing the boom 41 from sinking when the ride control is executed. When the pressure oil flowing from the bottom chamber Cb of the boom cylinder 45 into the accumulator 58 is at a high pressure, the ride control relief ৬২ may open. In this case, since the bottom chamber Cb of the boom cylinder 45 communicates with the hydraulic oil tank 57, the piston rod 45c of the boom cylinder 45 shortens and the boom 41 sinks. Therefore, when the boom bottom pressure Pb exceeds the second threshold value P2, there is a possibility of the boom 41 sinking due to the opening of the ride control relief ৬২, and it is determined that the first execution condition of the ride control is not satisfied.

[0067] If the result in step S50 is YES, the ride control unit 113 determines whether the travel speed Vt of the hydraulic excavator 1 satisfies the second execution condition of the ride control (step S60). The second execution condition is a condition for determining the necessity of suppressing vibrations caused by the travel of the hydraulic excavator 1. If the travel speed Vt satisfies the second execution condition (if YES), the process proceeds to step S70. If the travel speed Vt does not satisfy the second execution condition (if NO), the process proceeds to step S90, which switches the ride control to the stopped state.

[0068] Specifically, if the travel speed Vt of the hydraulic excavator 1, obtained by converting the detected value of the speed sensor 99 (rotation speed V of wheels 13 and 15), is greater than or equal to the first threshold V1 (Vt ≥ V1), it is determined that the second execution condition of ride control is met (YES). Otherwise, it is determined that the second execution condition is not met (NO). The first threshold V1 is, for example, a set value that can be input by the operator from an input device (for example, a monitor 33 with a touch panel). For example, a setting of 4 to 10 km / h is assumed for the first threshold V1.

[0069] If the result in step S60 is YES, the ride control unit 113 determines whether the third execution condition for the ride control is met based on whether or not the front work device 4 is operated by the operating device 26 (step S70). The third execution condition is a determination condition to prevent pressurized oil from the hydraulic pump 51 from flowing into the hydraulic circuit of the ride control when the ride control is activated by the operation of the front work device 4. If the front work device 4 is not operated by the operating device 26 (if YES), the process proceeds to step S80, which switches the ride control to the activated state. On the other hand, if the front work device 4 is operated by the operating device 26 (if NO), the process proceeds to step S90, which stops the ride control.

[0070] Specifically, if the operating pilot pressure Pp output by the operating device 26, which is the value detected by the second pressure sensor 97, is less than or equal to the third threshold P3 (Pp ≤ P3), it is determined that there is no operation on the front working device 4 and the third execution condition of ride control is met (YES). Otherwise, it is determined that there is an operation on the working device 4 and the third execution condition is not met (NO). The third threshold P3 is, for example, the operating pilot pressure at which each control valve of the control valve unit 53 does not drive.

[0071] If the result in step S70 is YES, the ride control unit 113 switches the ride control to the activated state (step S80). Specifically, it outputs a command to the first RC valve 59 and the second RC valve 63 (switching valve device) to switch to the second position R (first state). In addition, it controls the HRV release valve 73 so that the function of the HR valve 56 is released. That is, it outputs a command to the HRV release valve 73 to switch to the second position C. As a result, the function of the HR valve 56 is forcibly released (the HR valve 56 opens), and bidirectional flow between the bottom chamber Cb of the boom cylinder 45 and the accumulator 58 is permitted. Also, bidirectional flow between the rod chamber Cr of the boom cylinder 45 and the hydraulic oil tank 57 is permitted.

[0072] On the other hand, if the result in step S40 is NO, that is, if it is determined that ride control is in operation, the ride control unit 113 determines whether the travel speed Vt of the hydraulic excavator 1 satisfies the stop condition for ride control (step S110). If the travel speed Vt satisfies the stop condition (if YES), the process proceeds to step S90, which switches the ride control to the stop state. If the travel speed Vt does not satisfy the stop condition (if NO), the process proceeds to step S120.

[0073] Specifically, if the travel speed Vt obtained by converting the detected value of the speed sensor 99 (rotation speed V of wheels 13 and 15) is less than or equal to the second threshold V2 (V ≤ V2), it is determined that the ride control stopping condition is met (YES). Otherwise, it is determined that the stopping condition is not met (NO). The second threshold V2 is, for example, a setting value lower than the first threshold V1, which is the execution condition for ride control. For example, a setting of 2 km / h is assumed for the second threshold V2.

[0074] If the result in step S110 is NO, the ride control unit 113 determines whether the stop condition for the ride control is met based on whether or not the front work device 4 is operated using the operating device 26 (step S120). This stop condition, like the second execution condition for the ride control, is a determination condition to prevent pressurized oil from the hydraulic pump 51 from flowing into the hydraulic circuit of the ride control due to the operation of the front work device 4 while the ride control is in operation. If the front work device 4 is operated using the operating device 26 (if YES), the process proceeds to step S90, which switches the ride control to the stopped state. On the other hand, if the front work device 4 is not operated using the operating device 26 (if NO), the process proceeds to step S80, which activates the ride control.

[0075] Specifically, if the operating pilot pressure Pp output by the operating device 26, which is the value detected by the second pressure sensor 97, is equal to or greater than the fourth threshold P4 (Pp ≥ P4), it is determined that there has been an operation on the front working device 4 and that the stop condition for ride control has been met (YES). Otherwise, it is determined that there has been no operation on the working device 4 and that the stop condition has not been met (NO). The fourth threshold P4 is set to a value higher than the third threshold P3 of the third execution condition for ride control.

[0076] The control to switch the ride control to the stopped state (step S80) when YES is determined in step S120, and the control of the operating state of the ride control (step S90) when NO is determined in step S120, are the same as the controls for the first RC valve 59, the second RC valve 63, and the HRV release valve 73 described above.

[0077] Thus, the hydraulic excavator 1 is configured to switch the operation and deactivation of the ride control function according to various situations, even when the ride control is enabled, using, for example, the detected pressure of hydraulic cylinders such as the boom cylinder 45, the operating pilot pressure (operating pilot pressure Pp), and the detected value of the speed sensor. For example, when the vibration suppression instruction device (RC switch 31) instructs the control device 100 to enable the control of the vibration suppression function, it controls the switching valve device (first RC valve 59 and second RC valve 63) to a first state (second position R) or a second state (first position S) based on the detected pressure of the hydraulic cylinder by the pressure sensor, the detected value of the operating detector, and the detected value of the speed sensor.

[0078] For example, in this embodiment, if the instruction signal from the RC switch 31 indicates that the control device 100 is validating the control of the ride control, the control device 100 determines whether all three conditions for executing the ride control are met based on the detected value of the first pressure sensor 96 (boom bottom pressure Pb), the detected value of the second pressure sensor 97 (operating pilot pressure Pp of the operating device 26), and the detected value of the speed sensor 99 (rotation speed V of the wheels 13 and 15), and switches the ride control to either the activated or deactivated state. In addition, the control device 100 switches the ride control to either the activated or deactivated state based on the presence or absence of an instruction signal from the overload alarm switch 32 and the state of the axle lock (locking mechanism such as the axle lock valve 78) (locked or unlocked). Furthermore, if the ride control is activated, the control device 100 determines whether either of the two conditions for stopping the ride control is met, and switches the ride control to either the activated or deactivated state.

[0079] Next, the operation of the hydraulic system in the first embodiment of the wheeled construction machine of the present invention will be described. First, the operation of the hydraulic system when the front working device (boom) is operated when the RC switch of the hydraulic excavator is set to invalid will be explained using Figures 3 and 5.

[0080] When a boom-raising operation is performed on the operating device 26 shown in Figure 3, the operating pilot pressure (boom-raising command) generated by the operating device 26 drives the corresponding control valve of the control valve unit 53. As a result, pressurized oil from the hydraulic pump 51 is supplied to the piping connection chamber 86 of the HR valve 56 via the first actuator line 54. This opens the poppet valve 81 of the HR valve 56, and the pressurized oil from the hydraulic pump 51 is supplied from the piping connection chamber 86 of the HR valve 56 through the cylinder connection chamber 87 to the bottom chamber Cb of the boom cylinder 45. At this time, the hydraulic fluid in the rod chamber Cr of the boom cylinder 45 is discharged to the hydraulic fluid tank 57 via the second actuator line 55 and the control valve unit 53. As a result, the boom cylinder 45 extends and the boom-raising operation is performed.

[0081] When a boom lowering operation is performed on the operating device 26, the operating pilot pressure (boom lowering command) of the operating device 26 drives the corresponding control valve of the control valve unit 53. As a result, pressurized oil from the hydraulic pump 51 is supplied to the rod chamber Cr of the boom cylinder 45 via the second actuator line 55. At this time, the operating pilot pressure (boom lowering command) of the operating device 26 is input as a release pilot pressure to the pressure receiving part 82a of the pilot valve 82 of the HR valve 56 via the shuttle valve 74. Note that since ride control is not executed due to the invalidation instruction from the RC switch 31, the release pilot pressure of the HRV release valve 73 is not output from the shuttle valve 74. In the HR valve 56, the pilot valve 82 is displaced by the input of the release pilot pressure from the operating device 26, which connects the piping connection chamber 86 and the back pressure chamber 88, opening the poppet valve 81. As a result, the pressurized oil in the bottom chamber Cb of the boom cylinder 45 is discharged from the HR valve 56 to the hydraulic oil tank 57 via the first actuator line 54 and the control valve unit 53. This shortens the boom cylinder 45, allowing the boom to be lowered.

[0082] If the first actuator line 54 ruptures during boom raising operation, the pressure in the piping connection chamber 86 of the HR valve 56 will drop to atmospheric pressure. Meanwhile, the high load pressure of the bottom chamber Cb of the boom cylinder 45 is guided to the back pressure chamber 88 via the throttling passage 85a. As a result, the poppet valve 81 closes immediately, preventing pressurized oil from flowing out of the bottom chamber Cb of the boom cylinder 45 to the first actuator line 54, and thus preventing the boom 41 from falling.

[0083] Furthermore, when performing lifting operations using the front work device 4 as shown in Figure 5, the axle lock is locked. That is, the control device 100 (see Figure 4) outputs an off signal to the axle lock valve 78, thereby holding the axle lock valve 78 in the first position L (locked position). As a result, the pilot check valve 67 functions as a check valve, preventing the extension and retraction of the ram cylinder 66 and restricting the swinging of the axles 12 and 14. This prevents the slewing body 3 from becoming unstable during lifting operations.

[0084] Next, the operation of the hydraulic system when the RC switch on the hydraulic excavator is set to "enabled" will be explained using Figures 3 to 7. This assumes that the hydraulic excavator has started moving from the work site and is traveling on a public road.

[0085] The operator of hydraulic excavator 1 switches the RC switch 31 shown in Figure 4 to ON (enabled). If the instruction from the RC switch 31 is valid, the control device 100 determines whether the overload alarm switch 32 is ON or OFF (step S20 shown in Figure 6), and determines whether the axle lock is locked or OFF (step S30 shown in Figure 6).

[0086] When performing suspended load travel as shown in Figure 5, the overload warning switch 32 is typically turned ON and the axle lock is locked. Therefore, in the case of suspended load travel, the control device 100 shown in Figure 4 determines YES in step S20 or S30 shown in Figure 6, and even if the instruction from the RC switch 31 indicates that the control device 100 is effectively controlling the ride control, it stops the ride control (step S90). In other words, the control device 100 outputs an OFF signal to the first RC valve 59 and the second RC valve 63, and also outputs an OFF signal to the HRV release valve 73.

[0087] As a result, the first RC valve 59 and the second RC valve 63 shown in Figure 3 are held in the first position S (second state), and the HRV release valve 73 is held in the first position N (non-release position). Therefore, the flow from the bottom chamber Cb of the boom cylinder 45 to the accumulator 58 via the HR valve 56 is blocked, and the flow from the rod chamber Cr of the boom cylinder 45 to the hydraulic oil tank 57 is blocked. In addition, the function of the HR valve 56 is maintained without being released. For this reason, even if the first actuator line 54 breaks while the suspended load is traveling, the HR valve 56 functions as described above to prevent the outflow of pressurized oil from the bottom chamber Cb of the boom cylinder 45, thereby preventing the boom 41 from falling while traveling.

[0088] In this embodiment, whether or not the hydraulic excavator 1 is traveling with a suspended load is determined based on the instructions of the overload alarm switch 32 and the state of the axle lock. If it is traveling with a suspended load, the ride control is stopped even if the instructions of the RC switch 31 are valid. This prevents the vehicle body (slewing body 3) from becoming unstable due to the execution of ride control during travel with a suspended load. Furthermore, since there is no need to operate the RC switch 31 to disable ride control so that ride control is not executed during travel with a suspended load, the complexity of operator operation of the RC switch 31 can be reduced.

[0089] On the other hand, during normal travel other than when carrying a suspended load, the control device 100 determines whether all three execution conditions for ride control are met (steps S50 to S70 shown in Figure 6). During normal travel, the front work device 4 is held in the air without touching the ground, so the boom bottom pressure Pb is higher than the first threshold P1. Therefore, the control device 100 determines that the first execution condition for boom bottom pressure Pb is met (YES in step S50 shown in Figure 6). When the hydraulic excavator 1 reaches a travel state faster than the first threshold speed V1, the control device 100 determines that the second execution condition for travel speed Vt is met (YES in step S60 shown in Figure 6).

[0090] If the control device 26 is being operated while the vehicle is in motion, it is determined that the third execution condition for the operating pilot pressure Pp is not met (NO in step S70 shown in Figure 6), and even if the instruction on the RC switch 31 is valid, a command to stop the ride control is output (step S90 shown in Figure 6). This prevents high-pressure oil from the hydraulic pump 51 from flowing into the hydraulic circuit related to the ride control (such as the hydraulic circuit connecting the bottom chamber Cb of the boom cylinder 45 and the accumulator 58).

[0091] On the other hand, when the hydraulic excavator 1 travels with the front work device 4 stopped, the control device 100 determines that the third execution condition of the operating pilot pressure Pp is met (YES in step S70 shown in Figure 6), and outputs a command to activate the ride control in response to the Activate instruction of the RC switch 31 (step S80 shown in Figure 6). That is, the control device 100 outputs an ON signal to the HRV release valve 73 shown in Figure 3, and also outputs ON signals to the first RC valve 59 and the second RC valve 63. As a result, the HR valve 56 opens, allowing bidirectional flow between the bottom chamber Cb of the boom cylinder 45 and the accumulator 58, and also allowing bidirectional flow between the rod chamber Cr of the boom cylinder 45 and the hydraulic oil tank 57. Therefore, even if the front work device 4 vibrates during travel, the accumulator 58 absorbs the vibration energy, thus reducing pitching and bouncing of the slewing body 3 due to the movement of the front work device 4.

[0092] When the ride control is activated in this manner, the control device 100 determines whether the stop conditions for the ride control are met (from the NO determination in step S40 to S110 and S120 shown in Figure 6). If the front work device 4 is operated while the ride control is activated, the control device 100 determines that the stop conditions for the operating pilot pressure Pp are met (YES in step S120 shown in Figure 6) and switches the ride control to the stop state. Also, when the travel speed Vt of the hydraulic excavator 1 drops to or below the second threshold speed V2, the control device 100 determines that the stop conditions for the travel speed Vt are met (YES in step S110 shown in Figure 6) and outputs a command to stop the ride control.

[0093] Furthermore, when moving from the work site to a public road, mud adhering to the wheels may be removed before moving to the public road. For example, the operator stops the hydraulic excavator 1, which was being driven with the RC switch 31 turned ON. With the movement stopped, the ride control is in a stopped state. Then, the jack-up operation shown in Figure 7 is performed, and the wheels 13 and 15 are made to spin freely in the jack-up state. In this case, because the bucket 43 of the front work device 4 is in contact with the ground due to the jack-up operation, the boom bottom pressure Pb is lower than the first threshold P1.

[0094] At this time, since the RC switch 31 is ON (indicating it to be active) and the ride control is in a stopped state, the control device 100 determines whether the three execution conditions for the ride control are met (steps S50 to S70 shown in Figure 6). Even if the travel speed Vt obtained by converting the speed V of the slipping wheels 13 and 15 is equal to or greater than the first threshold V1 and there is no operation of the front work device 4, the boom bottom pressure Pb is lower than the first threshold P1, so it is determined that the first execution condition for the boom bottom pressure Pb is not met (NO in step S50 shown in Figure 6). Therefore, the control device 100 maintains the ride control in a stopped state.

[0095] If the ride control were to be activated by spinning the wheels 13 and 15 during the jacking operation, the pressurized oil in the rod chamber Cr of the boom cylinder 45 would flow out to the hydraulic oil tank 57 via the second RC valve 63 due to the load of the jacking, making it impossible to maintain the jacked-up position. Therefore, in this embodiment, considering that the boom bottom pressure Pb is lower during jacking up than during driving, the boom bottom pressure Pb is used as one of the conditions for executing the ride control. As a result, even if the RC switch 31 remains on (indicated as enabled), the ride control will not be activated during jacking up. Therefore, when spinning the wheels 13 and 15 while jacked up, there is no need to switch the RC switch 31 from on (enabled) to off (disabled) to prevent the ride control from being activated. In other words, when the vehicle body 2 and 3 are jacked up by the front work device 4, the control device 100 disables the vibration suppression function control, even if the vibration suppression indicator (RC switch 31) has indicated that the vibration suppression function control is enabled.

[0096] As described above, the wheeled hydraulic excavator 1 (wheeled construction machine) according to the first embodiment comprises a self-propelled vehicle body 2, 3 to which wheels 13, 15 are attached, a front working device 4 (working device) attached to the vehicle body 2, 3, a control device 100 that controls the flow of pressurized oil from hydraulic cylinders (boom cylinder 45, arm cylinder 46, bucket cylinder 47) that drive the front working device 4 (working device) and performs control of a vibration suppression function that suppresses vibration of the hydraulic cylinders (boom cylinder 45, arm cylinder 46, bucket cylinder 47) when the rotational speed of the wheels 13, 15 reaches a predetermined level, and an RC switch 31 as a vibration suppression indicator device that indicates whether the control device 100 controls the vibration suppression function or not. When the vehicle body 2, 3 is jacked up by the front working device 4 (working device), the control device 100 disables the control of the vibration suppression function even if the RC switch 31 (vibration suppression indicator device) has indicated that the control of the vibration suppression function is enabled.

[0097] With this configuration, even when the RC switch 31 (vibration suppression indicator) is instructed to enable the vibration suppression function, the vibration suppression function is disabled when the vehicle bodies 2 and 3 are jacked up by the front work device 4 (work device). Therefore, the operator does not need to perform any operation to disable the vibration suppression function on the RC switch 31 (vibration suppression indicator). In other words, the hassle of operating the RC switch 31 (vibration suppression indicator) can be reduced.

[0098] Furthermore, the wheeled hydraulic excavator 1 (wheeled construction machine) according to this embodiment includes a hydraulic pump 51 that supplies pressurized oil to the hydraulic cylinders (boom cylinder 45, arm cylinder 46, bucket cylinder 47), an accumulator 58 provided in the hydraulic line (first actuator line 54) between the hydraulic pump 51 and the hydraulic cylinder (boom cylinder 45) to absorb pressure fluctuations in the hydraulic cylinder (boom cylinder 45), and a second actuator that allows the flow of pressurized oil from the hydraulic cylinder (boom cylinder 45) to the accumulator 58 and also allows the flow of pressurized oil from the hydraulic cylinder (boom cylinder 45) to the hydraulic oil tank 57 (tank) to activate a vibration suppression function. The system includes a first RC valve 59 and a second RC valve 63 as a switching valve device that can switch between state 1 and state 2, which shuts off the flow of pressurized oil from the hydraulic cylinder (boom cylinder 45) to the accumulator 58 and also shuts off the flow of pressurized oil from the hydraulic cylinder (boom cylinder 45) to the hydraulic oil tank 57 (tank) to stop the vibration suppression function; an operating device 26 that outputs operating instructions for the front work device 4 (work device); a first pressure sensor 96 that detects the pressure of the boom cylinder 45 (hydraulic cylinder); a second pressure sensor 97 that acts as an operation detector that detects operating instructions from the operating device 26; and a speed sensor 99 that detects the rotational speed of the wheels 13 and 15. The control device 100 is configured to control the first RC valve 59 and the second RC valve 63 (switching valve device) to the second position R (first state) or the first position S (second state) based on the detected value Pb of the first pressure sensor 96, the detected value Pp of the second pressure sensor 97 (operation detector), and the detected value V of the speed sensor 99, when the RC switch 31 (vibration suppression indicator) indicates that the vibration suppression function control should be enabled.

[0099] With this configuration, in addition to the detection value Pp of the second pressure sensor 97 (operation detector) and the detection value V of the speed sensor 99, the pressure value (boom bottom pressure Pb) of the boom cylinder 45 (hydraulic cylinder) detected by the first pressure sensor 96 is used as the execution condition for the vibration suppression function by the accumulator 58. Therefore, it is possible to specify whether or not to switch to the operating state of the vibration suppression function depending on whether or not jacking up is performed using the front working device 4 (working device). Accordingly, when jacking up is performed when the RC switch 31 (vibration suppression indicator device) is operated and the indicator is active, it is possible to avoid switching to the operating state of the vibration suppression function by switching the RC switch 31 (vibration suppression indicator device) to the disabled state. In other words, the hassle of operating the RC switch 31 (vibration suppression indicator device) can be reduced.

[0100] In this embodiment, the working apparatus includes a boom 41, an arm 42, and a bucket 43. The hydraulic cylinder is a boom cylinder 45 that moves the boom 41 upward when pressurized oil is supplied to the bottom chamber Cb, and moves the boom 41 downward when pressurized oil is supplied to the rod chamber Cr. The first pressure sensor 96 detects the pressure in the bottom chamber Cb of the boom cylinder 45. When the control device 100 is instructed by the RC switch 31 (vibration suppression indicator) to enable the control of the vibration suppression function, if the detected value of the first pressure sensor 96 (boom bottom pressure Pb) is lower than a preset first threshold P1, the control device 100 is configured to control the first RC valve 59 and the second RC valve 63 (switching valve device) to the second position R (first state) or the first position S (second state).

[0101] With this configuration, when the hydraulic excavator 1 is in a jacked-up state, the vibration suppression function can be reliably stopped.

[0102] Furthermore, in this embodiment, when the control device 100 controls the first RC valve 59 and the second RC valve 63 (switching valve device) so that the vibration suppression function is activated, it is configured to control the first RC valve 59 and the second RC valve 63 (switching valve device) based on the detection value V of the speed sensor 99 and the detection value Pp of the second pressure sensor 97 (operation detector), regardless of the detection value (boom bottom pressure Pb) of the first pressure sensor 96.

[0103] This configuration prevents the vibration suppression function from being unnecessarily stopped even if the boom bottom pressure Pb decreases while the vibration suppression function is operating. When the front working device 4 vibrates upward while the vibration suppression function is operating, the boom bottom pressure Pb temporarily decreases before pressurized oil flows into the bottom chamber Cb of the boom cylinder 45. As a result, the boom bottom pressure Pb may fall below the first threshold P1. If the vibration suppression function is stopped at this time, it will not be able to perform effectively. Therefore, this configuration prevents switching to a stopped state of the vibration suppression function.

[0104] Furthermore, the wheeled hydraulic excavator 1 (wheeled construction machine) of this embodiment is equipped with axles 12 and 14 that rotatably support the wheels 13 and 15 and are pivotable relative to the vehicle bodies 2 and 3, and locking mechanisms 67 and 78 that prevent the axles 12 and 14 from pivoting. The locking mechanisms 67 and 78 are controlled to switch between a locked state and an unlocked state. In addition, when the control device 100 is instructed by the RC switch 31 (vibration suppression indicator) to enable the control of the vibration suppression function, it controls the first RC valve 59 and the second RC valve 63 (switching valve device) to the second position R (first state) or the first position S (second state) based on the detected value Pb of the first pressure sensor 96, the detected value Pp of the second pressure sensor 97 (operation detector), the detected value V of the speed sensor 99, and the state of the locking mechanisms 67 and 78.

[0105] With this configuration, the vibration suppression function is deactivated when the locking mechanisms 67 and 78, which are activated during load transport, are locked, thereby preventing instability of the slewing body 3 (vehicle body) caused by the operation of the vibration suppression function during load transport. In other words, there is no need to switch the instruction of the RC switch 31 (vibration suppression indicator device) from enabled to disabled in order to prevent instability of the slewing body 3 (vehicle body) caused by the operation of the vibration suppression function during load transport. That is, the hassle of operating the RC switch 31 (vibration suppression indicator device) can be reduced.

[0106] Furthermore, the wheeled hydraulic excavator 1 (wheeled construction machine) of this embodiment is equipped with an overload alarm switch 32, which serves as an overload alarm indicator device that signals overload alarm control to issue an alarm when the load of the lifting operation by the front work device 4 (work device) is excessive. In addition, when the control device 100 is instructed by the RC switch 31 (vibration suppression indicator device) to enable the control of the vibration suppression function, it controls the first RC valve 59 and the second RC valve 63 (switching valve device) to the second position R (first state) or the first position S (second state) based on the detection value Pb of the first pressure sensor 96, the detection value Pp of the second pressure sensor 97 (operation detector), the detection value V of the speed sensor 99, and whether or not an overload alarm control instruction has been issued from the overload alarm switch 32 (overload alarm indicator device).

[0107] With this configuration, the vibration suppression function is deactivated when the overload alarm switch 32 (overload alarm indicator) is activated during load transport, thereby preventing instability of the slewing body 3 (vehicle body) caused by the vibration suppression function during load transport. In other words, there is no need to switch the RC switch 31 (vibration suppression indicator) from enabled to disabled in order to prevent instability of the slewing body 3 (vehicle body) caused by the vibration suppression function during load transport. That is, the hassle of operating the RC switch 31 (vibration suppression indicator) can be reduced.

[0108] Furthermore, the wheeled hydraulic excavator 1 (wheeled construction machine) of this embodiment is equipped with a hose rupture valve 56 installed in the first actuator line 54 (hydraulic line) that has the function of preventing pressurized oil from flowing from the boom cylinder 45 (hydraulic cylinder) to the first actuator line 54 (hydraulic line) when the first actuator line 54 (hydraulic line) ruptures, and an HRV release valve 73 (release valve) that can be switched to either maintain or release the function of the hose rupture valve 56. The accumulator 58 is connected to the boom cylinder 45 (hydraulic cylinder) via the hose rupture valve 56. Furthermore, the control device 100 is configured to control the HRV release valve 73 (release valve) in addition to the first RC valve 59 and the second RC valve 63 (switching valve device), and when the first RC valve 59 and the second RC valve 63 (switching valve device) are controlled to the second position R (first state), the HRV release valve 73 (release valve) is controlled so that the function of the hose rupture valve 56 is released, and when the first RC valve 59 and the second RC valve 63 (switching valve device) are controlled to the first position S (second state), the HRV release valve 73 (release valve) is controlled so that the function of the hose rupture valve 56 is maintained.

[0109] With this configuration, even if a hose rupture valve 56 is installed on the boom cylinder 45 (hydraulic cylinder) on which the weight of the front work device 4 acts, the vibration suppression function can be activated by releasing the function of the hose rupture valve 56 with the HRV release valve 73 (release valve).

[0110] [Second Embodiment] Next, a second embodiment of the wheeled construction machine of the present invention will be described with reference to Figure 8. Figure 8 is a block diagram showing the schematic configuration of the hydraulic system and the travel system in the wheeled construction machine according to the second embodiment of the present invention. In Figure 8, parts with the same reference numerals as those in Figures 1 to 7 are similar parts, so their detailed explanation will be omitted.

[0111] The second embodiment of the wheeled construction machine of the present invention shown in Figure 8 differs from the first embodiment in three main ways. First, the accumulator 58A is connected to the bottom chamber Cb of the boom cylinder 45 via the first RC valve 59 without going through the HR valve 56. Second, the ride control relief valve 61 in the first embodiment has been removed (see Figure 3). Third, the HRV release valve 73 in the first embodiment has been removed (see Figure 3).

[0112] In detail, the bottom chamber Cb of the boom cylinder 45 and the cylinder connection chamber 87 of the HR valve 56 are connected via a third connection line 69. The accumulator 58A is connected to the third connection line 69 via a first connection line 60A. That is, the accumulator 58A is connected to the bottom chamber Cb of the boom cylinder 45 without going through the HR valve 56. Therefore, even without disabling the function of the HR valve 56, the accumulator 58A and the bottom chamber Cb of the boom cylinder 45 are connected by switching the first RC valve 59, enabling the operation of the ride control. Furthermore, by increasing the pressure resistance of the accumulator 58A, the ride control relief valve 61 in the first embodiment becomes unnecessary.

[0113] In this embodiment, it is not necessary to deactivate the function of the HR valve 56 in order to activate the ride control. Therefore, the configuration for deactivating the function of the HR valve 56 when the ride control is executed in the first embodiment is unnecessary. In other words, the HRV release valve 73, shuttle valve 74, second pilot line 76, and third pressure sensor 98 in the first embodiment have been eliminated.

[0114] The control device 100 according to this embodiment is configured to perform ride control by controlling only the first RC valve 59 and the second RC valve 63, thereby suppressing vibrations during travel (when the rotational speed of the wheels 13 and 15 reaches a predetermined level) using the accumulator 58A. In other words, the control device according to this embodiment is configured in the same way as the control device 100 according to the first embodiment shown in Figure 4, except that the input of the detected value from the third pressure sensor 98 is removed, and the output of the command to the HRV release valve 73 is also removed. In other words, the control device according to this embodiment differs from the control device according to this embodiment only in the processing method of the operating state or stopped state of the ride control in steps S80 and S90 of the processing procedure of the ride control unit 113 shown in Figure 6. The determination of the execution conditions and stop conditions of the ride control in steps S10 to S70 are exactly the same.

[0115] According to the second embodiment of the wheeled construction machine of the present invention described above, similar to the first embodiment described above, even when the RC switch 31 (vibration suppression indicator) is instructed to enable the vibration suppression function, the vibration suppression function is disabled when the vehicle body 2, 3 is jacked up by the front work device 4 (work device). Therefore, the operator does not need to perform an operation to instruct the RC switch 31 (vibration suppression indicator) to disable the vibration suppression function. In other words, the hassle of operating the RC switch 31 (vibration suppression indicator) can be reduced.

[0116] [Other embodiments] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. The embodiments described above are explained in detail for the purpose of making the present invention easy to understand, and are not necessarily limited to those having all the configurations described. For example, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0117] For example, in the embodiment described above, a wheeled hydraulic excavator 1 was used as an example of a wheeled construction machine, but it can be broadly applied to wheeled construction machines equipped with work devices such as wheel loaders.

[0118] Furthermore, in the above-described embodiment, an example was shown in which at least one of the axles 12 and 14 is pivotably attached to the frame 11, and a locking mechanism 66, 67, 78 is provided to prevent the axles 12 and 14 from swinging. However, it is also possible to configure both axles 12 and 14 to be fixed to the frame 11. In this case, the determination step S30 regarding axle lock is omitted in the processing procedure of the ride control unit 113 of the control device 100 shown in Figure 6.

[0119] Furthermore, in the above-described embodiment, an example was shown in which the operating device 26, which outputs operation instructions for the front work device 4, generates the operating pilot pressure for the control valve unit 53 and the release pilot pressure for the HR valve 56. However, it is also possible to configure the operating device as an electric type, and have an electromagnetic proportional valve generate the operating pilot pressure for the control valve unit 53 and the release pilot pressure for the HR valve 56 using the discharge pressure of the pilot pump 71 as the source pressure. In this case, the control device generates the operating pilot pressure and the release pilot pressure by controlling the electromagnetic proportional valve in accordance with the operation signal of the electric operating device. At this time, the operating device itself, which outputs the operation signal to the control device 100, can be configured as the operation detector that detects the operation instructions from the operating device.

[0120] Furthermore, in the above-described embodiment, an example was shown in which the control device 100 that performs ride control is configured to perform axle lock switching control. However, it is also possible for the control device that performs axle lock switching control and the control device 100 that performs ride control to be configured differently. [Explanation of Symbols]

[0121] 1...Wheel-type hydraulic excavator (wheel-type construction machine), 2...Traction body (vehicle body), 3...Slewing body (vehicle body), 4...Front working device (working device), 12, 14...Axle, 13...Front wheel (wheel), 15...Rear wheel (wheel), 26...Operating device, 31...Ride control switch (vibration suppression indicator device), 32...Overload warning switch (overload warning indicator device), 43...Boom, 44...Arm, 45...Bucket, 45...Boom cylinder (hydraulic cylinder), Cb...Bottom chamber, Cr...Rod chamber, 51...Hydraulic pump, 54...First actuator line (hydraulic line), 56...Hose rupture valve, 57...Hydraulic oil tank (tank), 58, 58A...Accumulator, 59...First ride control valve (switching valve device), 63...Second ride control valve (switching valve device), 66... ​​Ram cylinder (locking mechanism), 67... Pilot check valve (locking mechanism), 73... Hose rupture valve release valve (release valve), 78... Axle lock valve (locking mechanism), 96... First pressure sensor (pressure sensor), 97... Second pressure sensor (operation detector), 99... Speed ​​sensor, 100... Control device

Claims

1. A self-propelled vehicle body with wheels attached, A work device attached to the vehicle body, A control device that controls the flow of pressurized oil from a hydraulic cylinder that drives the work device and executes a vibration suppression function to suppress vibration of the hydraulic cylinder when the rotational speed of the wheel reaches a predetermined level, A wheeled construction machine equipped with a vibration suppression instruction device that instructs whether to enable or disable the control of the vibration suppression function by the control device, A hydraulic pump that supplies pressurized oil to the hydraulic cylinder, An accumulator is provided in the hydraulic line between the hydraulic pump and the hydraulic cylinder, and absorbs pressure fluctuations in the hydraulic cylinder. A switching valve device that can switch between a first state in which pressurized oil flows from the hydraulic cylinder to the accumulator and also from the hydraulic cylinder to the tank to activate the vibration suppression function, and a second state in which the flow of pressurized oil from the hydraulic cylinder to the accumulator and also from the hydraulic cylinder to the tank to stop the vibration suppression function, An operating device that outputs operating instructions for the aforementioned work device, A pressure sensor for detecting the pressure of the hydraulic cylinder, An operation detector that detects the operation instruction from the operation device, A speed sensor for detecting the rotational speed of the wheel, A hose rupture valve is installed in the hydraulic line and has the function of preventing pressurized oil from leaking from the hydraulic cylinder into the hydraulic line when the hydraulic line ruptures. The system further comprises a release valve that can be switched to either maintain or release the function of the hose rupture valve, The accumulator is connected to the hydraulic cylinder via the hose rupture valve, The control device is When the vehicle body is jacked up by the work device, even if the vibration suppression indicator device has indicated that the vibration suppression function is enabled, the vibration suppression function is disabled. If the vibration suppression instruction device instructs that the vibration suppression function be enabled, the switching valve device is controlled to the first state or the second state based on the detected value of the pressure sensor, the detected value of the operation detector, and the detected value of the speed sensor. When controlling the switching valve device to the first state, the release valve is controlled so that the function of the hose rupture valve is released. When controlling the switching valve device to the second state, the release valve is controlled so that the function of the hose rupture valve is maintained. A wheeled construction machine characterized by the following features.

2. In the wheeled construction machine described in claim 1, The aforementioned work device includes a boom, an arm, and a bucket. The hydraulic cylinder is a boom cylinder that moves the boom upward when pressurized oil is supplied to the bottom chamber and moves the boom downward when pressurized oil is supplied to the rod chamber. The pressure sensor detects the pressure in the bottom chamber of the boom cylinder, When the control device is instructed by the vibration suppression instruction device to enable the control of the vibration suppression function, if the detected value of the pressure sensor is lower than a preset threshold, the control device controls the switching valve device to the second state. A wheeled construction machine characterized by the following features.

3. In the wheeled construction machine described in claim 1, An axle that rotatably supports the wheel and is pivotable relative to the vehicle body, The axle is equipped with a locking mechanism that prevents it from swinging, The locking mechanism is controlled to switch between either a locked state or an unlocked state. When the vibration suppression instruction device instructs the control device to enable the control of the vibration suppression function, the control device controls the switching valve device to the first state or the second state based on the detected value of the pressure sensor, the detected value of the operation detector, the detected value of the speed sensor, and the state of the locking mechanism. A wheeled construction machine characterized by the following features.

4. In the wheeled construction machine described in claim 1, The device includes an overload alarm instruction device that instructs overload alarm control to issue an alarm when the load of the lifting operation by the aforementioned work device is excessive, When the vibration suppression instruction device has instructed the control device to enable the control of the vibration suppression function, the control device controls the switching valve device to the first state or the second state based on the detected value of the pressure sensor, the detected value of the operation detector, the detected value of the speed sensor, and whether or not the overload alarm control instruction device has been issued. A wheeled construction machine characterized by the following features.

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