Construction Machinery

Abstract

To provide a construction machine which enables an operator to recognize that an operation of an operation lever is an operation in an operation region over a dead zone region in an operation device configured to be usable for a hydraulic actuator for operating a work machine.SOLUTION: An operation device for operating an earth removal device in a construction machine comprises: a pilot valve 120 for outputting pilot pressure to an operation lever 101 and a direction chancing valve; and an interlocking mechanism for interlocking an operation of the pilot valve 120 with an operation amount of the operation lever 101. The interlocking mechanism comprises: a lever support 141 for swingably supporting the operation lever 101; a compression spring 159 serving as reactive force application means for applying a reactive force against swinging of the operation lever 101 to the lever support 141; and a regulation part 150 for regulating the application of the reactive force from the compression spring 159 to the operation lever 101.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a construction machine having a work implement. [Background technology]

[0002] Conventionally, construction machines such as excavation vehicles are equipped with hydraulic cylinders as hydraulic actuators for driving working machines such as front working machines and soil removal devices. For example, a soil removal device provided on a construction machine includes a lifting arm that is provided so as to be swingable in the vertical direction relative to a traveling device that constitutes the machine, a soil removal blade (blade) attached to the tip of the lifting arm, a blade lifting cylinder that moves the blade in the vertical direction by swinging the lifting arm in the vertical direction, an angle cylinder that rotates the blade in the front-rear direction (angle rotation), and a tilt cylinder that rotates the blade in the vertical direction (tilt rotation) (see, for example, Patent Document 1).

[0003] Patent Document 1 also discloses a configuration in which the elevation and lowering of the blade is controlled by an operating device equipped with a pressure reducing pilot valve and a blade operating lever that operates the blade lift cylinder, and a blade control valve (directional control valve) provided in an oil passage between the blade lift cylinder and the hydraulic pump. In such a configuration, the operator tilts the blade operating lever of the operating device and supplies pilot pressure from the hydraulic pilot valve to the blade control valve, thereby causing the blade lift cylinder to extend and retract.

[0004] A pilot valve incorporated in a pilot-type operating device that supplies pilot pressure to a directional control valve that controls the flow rate and direction of hydraulic pressure to a hydraulic cylinder is a spool-type pilot valve in which a spool is inserted into a hole in a substantially cylindrical shape and the pilot pressure is output from an output port by displacing the spool via a pressure rod. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-167686 A Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, in a pilot-type operating device that supplies pilot pressure to a directional control valve that controls the flow rate and direction of hydraulic pressure to a hydraulic cylinder, a dead zone is provided in the operating area of ​​the operating lever to prevent malfunction of the work machine when the operator accidentally touches the operating lever. The dead zone is a region of the operating area of ​​the operating lever where the hydraulic actuator corresponding to the operating lever does not operate even if the operator operates the operating lever. When a spool-type pilot valve is used in the operating device, in which a compression spring for setting the pilot pressure and a return spring for returning the pressing rod and the spool to their initial positions are provided on the outer periphery of the spool, the dead zone is affected by the range until the spool starts to move, depending on the relationship between the repulsive force of the spring in the pilot valve and the pressing force applied to the pressing rod via the operating lever. In this case, the range of the dead zone is affected by manufacturing variations in the spring in the pilot valve, etc., so that the dead zone of the operating device varies depending on the individual differences of the pilot valve.

[0007] In the pilot-type operating device disclosed in Patent Document 1, the dead zone is essentially determined by a spring in the pilot valve, so there is no difference in the force (operating torque) that the operator applies to the operating lever when tilting the operating lever between the dead zone and the operating zone where the hydraulic actuator operates. For this reason, the operator cannot recognize the timing when the operation of the operating lever has exceeded the dead zone and reached the operating zone, and it is also difficult for him or her to recognize the timing when the hydraulic actuator starts to operate.

[0008] Furthermore, one of the tasks performed using construction machinery equipped with a soil discharge device is leveling work. This leveling work involves leveling soil and sand with the blade of the soil discharge device, and the operator adjusts the height of the blade according to the target height of the leveling work. In this case, the operator performs an inching operation by repeatedly tilting the operating lever back and forth with a small amount of operation in order to move the blade up and down in small increments. With the pilot-type operating device disclosed in Patent Document 1, the operator cannot recognize whether each operation of the operating lever during the inching operation was within the operating range beyond the dead band area. This causes a problem that it is difficult to perform the inching operation.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a construction machine in which an operating device corresponding to a hydraulic actuator for operating a work machine is configured to enable the operator to recognize that operation of an operating lever is within an operating range beyond the dead zone. [Means for solving the problem]

[0010] The construction machine according to the present invention is a construction machine equipped with an operating device that operates a directional control valve that controls the flow rate and direction of pressure oil supplied to a hydraulic actuator, and the operating device comprises an operating lever that is operated to swing, a pilot valve that outputs pilot pressure to the directional control valve, and a linkage mechanism that links the output of the pilot valve to the operation of the operating lever, and the linkage mechanism is connected to a control unit that controls the output of the pilot pressure of the pilot valve, and comprises a lever support part that supports the operating lever so that it can swing freely, a reaction force applying means that applies a reaction force against the swing of the operating lever to the lever support part, and a regulating part that regulates the application of the reaction force by the reaction force applying means, and is characterized in that the operation amount of the operating lever is transmitted to the pilot valve in a state where the reaction force is regulated by the regulating part.

[0011] In addition, a construction machine according to another aspect of the present invention is characterized in that the reaction force applying means of the operating device has an elastic member that is deformable between a first state in which it is compressed depending on the amount of operation of the operating lever and a second state in which the operating lever is operated beyond a predetermined amount of operation, and when the elastic member is in the first state, it applies a reaction force to the lever support portion, and when the elastic member is in the second state, the application of the reaction force to the lever support portion is regulated by the regulating portion.

[0012] In addition, a construction machine according to another aspect of the present invention is characterized in that, in the interlocking mechanism of the operating device, the interlocking mechanism has a connecting portion that connects the base end of the operating lever and the reaction force imparting means via a link structure.

[0013] In addition, a construction machine according to another aspect of the present invention is characterized in that the regulating portion of the operating device has a first regulating portion corresponding to one of the swing directions of the operating lever, and a second regulating portion corresponding to the other swing direction of the operating lever.

[0014] In addition, in a construction machine according to another aspect of the present invention, the elastic member in the reaction force imparting means of the operating device is a compression spring, the interlocking mechanism comprises a support pillar having one end connected to the connecting portion, and a pair of tubular members which slidably hold the support pillar therein and have a flange at one end against which an end of the compression spring abuts, the first regulating portion is one of the pair of tubular members, the second regulating portion is the other of the pair of tubular members, and the pair of tubular members are separated from each other by the biasing force of the compression spring when the operating lever is not operated.

[0015] In addition, in a construction machine according to another aspect of the present invention, the pilot valve of the operating device comprises an output port which outputs the pilot pressure, an input port to which pressurized oil pumped from a hydraulic pump is input, a discharge port to discharge the pressurized oil input from the input port to a tank, a spool sliding hole communicating with the output port, the input port and the discharge port, a spool which slides and displaces the spool sliding hole, and a tilting portion which tilts in accordance with the amount of operation of the operating lever and slides and displaces the spool. Effect of the Invention

[0016] According to the present invention, in a configuration of an operating device corresponding to a hydraulic actuator for operating a work machine, it is possible to make an operator recognize that operation of the operating lever is within an operating range beyond the dead zone. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a left side view of a construction machine according to an embodiment of the present invention. [Diagram 2] 1 is a perspective view of a construction machine according to an embodiment of the present invention, seen from the left rear side. [Diagram 3] FIG. 2 is a plan view illustrating a configuration of a lower running body according to an embodiment of the present invention. [Figure 4] FIG. 2 is an enlarged perspective view illustrating an installation mode in a driving section of the operating device according to one embodiment of the present invention. [Diagram 5] 4 is a hydraulic circuit of a blade cylinder of an operating device according to one embodiment of the present invention. [Figure 6] 1 is a diagram illustrating a configuration of an operating device according to an embodiment of the present invention. [Figure 7] 1A to 1C are diagrams illustrating the operation of an operating device according to an embodiment of the present invention. [Figure 8] 4 is a schematic side view illustrating a link structure, a reaction force application means, and a regulating portion of the operating device according to one embodiment of the present invention. FIG. [Figure 9]4 is a schematic side view illustrating a link structure, a reaction force application means, and a regulating portion of an operating device according to an embodiment of the present invention. FIG. [Figure 10] 4 is a schematic side view illustrating a link structure, a reaction force application means, and a regulating portion of an operating device according to an embodiment of the present invention. FIG. [Figure 11] 4 is a schematic side view illustrating a link structure, a reaction force application means, and a regulating portion of an operating device according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention aims to allow an operator to recognize that the operation of a control lever is within an operating range that operates a hydraulic actuator in a construction machine having a working implement by devising a configuration of an operating device corresponding to a hydraulic actuator for operating the working implement. Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] In this embodiment, an excavation machine, which is a slewing work vehicle, will be described as an example of the construction machine according to the present invention. However, the construction machine according to the present invention is not limited to excavation machines, and can be widely applied to other construction machines such as crane work machines and wheel loaders.

[0020] First, the overall configuration of an excavation machine 1 according to this embodiment will be described with reference to Figures 1 and 3. As shown in Figures 1 and 2, the excavation machine 1 has an excavation device 3 and an earth removal device 4 as working machines attached to a self-propelled traveling vehicle body.

[0021] The excavation machine 1 has a pair of left and right crawler-type traveling sections 5, 5, a machine body frame 6 interposed between the left and right traveling sections 5, 5 as a base, and a rotating frame 7 provided on the machine body frame 6.

[0022] In this excavator 1, the lower traveling body 20A includes the machine body frame 6 and the traveling sections 5, 5 supported on both the left and right sides thereof, while the upper rotating body 20B includes the swivel frame 7 rotatably mounted on the lower traveling body 20A and the driver section 50 provided on the swivel frame 7. A swivel bearing 8 (see FIG. 3) having a circular shape in a plan view is disposed on the upper surface of the machine body frame 6, and the bottom surface of the swivel frame 7 is connected onto the swivel bearing 8. The upper rotating body 20B rotates relative to the lower traveling body 20A by connecting the machine body frame 6 and the swivel frame 7 via the swivel bearing 8. The center of the circle of the swivel bearing 8 is the center of rotation of the upper rotating body 20B relative to the lower traveling body 20A.

[0023] The traveling unit 5 has a configuration in which a crawler belt is wound around a rotating body such as a plurality of sprockets supported by the machine frame 6. The traveling unit 5 has, at its rear end, a driving sprocket 5a, which is a driving wheel, as a rotating body.

[0024] The soil removal device 4 is attached to the front side of the machine frame 6. The soil removal device 4 includes a support frame 40 and a blade 41, which is a blade supported by the support frame 40. The soil removal device 4 including these components is configured to be substantially symmetrical overall.

[0025] The support frame 40 is supported on the lower running body 20A so as to be vertically rotatable, and includes left and right arms 43 extending in the front-rear direction between the left and right running parts 5, 5, and a support cylinder part 42 installed between the left and right arms 43. The left and right arms 43 are attached to the machine body frame 6 so as to be vertically rotatable, with their base ends supported by support brackets 6b (see FIG. 3) provided on the front of the machine body frame 6 with the left-right direction as the rotation axis direction.

[0026] A blade cylinder 44 is disposed in the left-right center between the left and right arms 43 of the support frame 40. The blade cylinder 44 is disposed in a state of being bridged between the machine frame 6 and the support tube portion 42, with the extension direction (longitudinal direction) of the cylinder aligned along the front-rear direction. The front end portion of the blade cylinder 44 is supported by the support tube portion 42. The rear end portion of the blade cylinder 44 is supported by a support bracket 6a provided at the front of the machine frame 6 so as to be vertically rotatable with the left-right direction as the rotation axis direction.

[0027] Therefore, the pair of left and right arms 43 rotate up and down by expansion and contraction of a blade cylinder 44 provided in the left and right central portion between the machine frame 6 and the support frame 40. In other words, by operating the blade cylinder 44, the blade 41 is raised and lowered via the support frame 40.

[0028] The rotating frame 7 is provided to be capable of rotating in either the left or right direction around a vertical axis relative to the machine frame 6. The rotating frame 7 is also configured to be capable of rotating within the left-right width of the left and right running sections 5, 5, that is, within the width between the left outer edge of the left running section 5 and the right edge of the right running section 5. This enables the excavation machine 1 to perform small turning operations.

[0029] The excavation device 3 is a front working machine provided at the front of the upper rotating body 20B. A support bracket 7a for supporting the excavation device 3 is provided protruding forward from the left-right center of the front end of the rotating frame 7. A boom support bracket 31 forming the base end of the excavation device 3 is supported by the support bracket 7a so as to be rotatable with the vertical direction as the rotation axis direction.

[0030] The excavation device 3 has a boom 32 that constitutes its base side portion, an arm 33 connected to the tip side of the boom 32, and a bucket 34 attached to the tip of the arm 33. The excavation device 3 is arranged to swing left and right relative to the revolving frame 7 by a swing cylinder (not shown) arranged on the right side of its base end portion.

[0031] The excavation device 3 has a boom cylinder 35 that rotates the boom 32, an arm cylinder 36 that rotates the arm 33, and a bucket cylinder 37 that rotates the bucket 34. In the excavation device 3, the bucket 34 is detachably attached as a work attachment, and other attachments such as a clamping machine (fork) or a crusher (breaker) are attached in place of the bucket 34 depending on the work content.

[0032] A counterweight 9 is provided at the rear end of the upper rotating body 20B to balance the excavation device 3. The configuration of the counterweight 9 is changed according to the weight of the attachment attached to the tip of the arm 13 of the excavation device 3.

[0033] A driving unit 50, which allows an operator to drive and operate the traveling unit 5, excavation device 3, and soil removal device 4, is provided on the rotating frame 7. The driving unit 50 has a flat floor 58, which is provided on the left side of the front half of the rotating frame 7. A tank unit 59 is provided on the right side of the driving unit 50. The left side of the floor 58 serves as an entrance for the operator to get on and off the driving unit 50. In addition, a prime mover unit 11 including an engine etc. is provided on the rear of the rotating frame 7.

[0034] A canopy 51 is provided on the revolving frame 7 to cover the upper part of the driving section 50. The canopy 51 has a pair of left and right support pillars 52, 52 erected above the prime mover section 11, which is the rear end part of the revolving frame 7, and a roof section 53 supported by the left and right support pillars 52, 52.

[0035] In the driving section 50, a driver's seat support base 55 is provided behind a floor section 58, and a driver's seat 56 is provided on the driver's seat support base 55. A hydraulic oil tank for storing hydraulic oil is provided in a tank section 59 provided on the right side of the driving section 50. The hydraulic oil in the hydraulic oil tank is supplied to each hydraulic cylinder, which is a hydraulic actuator equipped in the excavation machine 1.

[0036] Around the driver's seat 56, there are provided an operation panel having various operation parts such as an operating lever 101 for operating the traveling part 5, the excavation device 3 and the soil removal device 4, and switches. In front of the driver's seat 56, a pair of left and right traveling levers 57, 57 are provided extending upward from a floor part 58. The traveling part 5 is operated by tilting each of the traveling levers 57, 57 in the forward and backward directions. A plurality of operation pedals for work are provided on both the left and right sides of the traveling levers 57, 57 on the floor part 58.

[0037] An operating device 100 for operating the soil removal device 4 is provided on the right side (tank section 59 side) of the driver's seat 56. The operating device 100 includes an operating lever 101 that the operator swings back and forth to move the blade 41 up and down, a pilot valve 120 in which a spool-type valve section is accommodated in a valve body section 121, and an interlocking mechanism that interlocks the operation of the pilot valve 120 with the amount of operation of the operating lever 101. In FIG. 4, for the convenience of explaining the mounting state of the operating device 100, the pilot valve 120 is shown with the operating lever 101 and the main components of the interlocking mechanism removed from the operating device 100. The operating device 100 is screwed to a support section 105 provided on the wall section on the tank section 59 side by a bolt 149 via a mounting section 131 provided on the pilot valve 120. In addition, each port (D, N, U) of the pilot valve 120 is connected to a hydraulic hose 106.

[0038] In the excavation work machine 1 having the above-mentioned configuration, the desired work is performed by an operator seated in the driver's seat 56 appropriately operating the travel levers 57, 57 and the work operation levers. Specifically, for example, the travel levers 57, 57 are operated to cause the traveling section 5 to travel forward and backward in a straight line or turn left and right. In addition, excavation work is performed by the excavation device 3, or soil removal work or ground leveling work is performed by the soil removal device 4, by operating the work operation lever.

[0039] The operating device 100 for the earth removal device 4 according to this embodiment will be further described with reference to Fig. 5 to Fig. 11. Fig. 5 shows an overview of a hydraulic circuit 110 for the blade cylinder 44, which is a hydraulic actuator for raising and lowering the blade 41 of the earth removal device 4.

[0040] The hydraulic circuit 110 that drives the blade cylinder 44 has a first hydraulic pump 111, a second hydraulic pump 112, a directional control valve 113, and a pilot valve 120. In Fig. 5, the path of the hydraulic oil supplied to the double-acting blade cylinder 44 is shown by a solid line, and the path of the pilot oil supplied to the directional control valve 113 is shown by a dashed line.

[0041] The first hydraulic pump 111 is driven by an engine 115 as a power source, and discharges pressurized hydraulic oil (pressurized oil) to be supplied to the blade cylinder 44. A directional control valve 113 is interposed between the first hydraulic pump 111 and the blade cylinder 44, and the flow direction and flow rate of the pressurized oil discharged by the first hydraulic pump 111 are switched by the directional control valve 113. The directional control valve 113 controls the amount of pressurized oil supplied from the hydraulic oil tank 114 to the blade cylinder 44 by the drive of the first hydraulic pump 111, and is therefore also called a control valve.

[0042] The second hydraulic pump 112 is driven by the engine 115 as a power source, similar to the first hydraulic pump 111, and discharges pilot oil as a command input to the directional control valve 113. The pilot oil discharged from the second hydraulic pump 112 is supplied to a pilot valve 120. The pilot valve 120 that has received the pilot oil outputs pilot pressure as a command to the directional control valve 113 in accordance with the operation direction and operation amount of the operating lever 101.

[0043] The directional control valve 113 is a center bypass type four-way three-position directional control valve, and has two pilot ports C1, C2 to which pilot pressure is input, and four connection ports A, B, P, R whose connection state is switched by sliding a spool (not shown). The two pilot ports C1, C2 correspond to the operation direction of the operation lever 101 of the operation device 100. When pilot pressure is not applied to either of the two pilot ports C1, C2 of the directional control valve 113, the directional control valve 113 is held in the neutral position by the biasing force of a spring (not shown). When the directional control valve 113 is in the neutral position, the connection ports A, B are closed, and the pressure oil discharged from the first hydraulic pump 111 is discharged to the hydraulic oil tank 114 through the center bypass flow path that flows from the connection port P to the connection port R. At this time, the pressure oil is not supplied to the blade cylinder 44.

[0044] When pilot pressure is applied to one of the two pilot ports C1, C2 of the directional control valve 113, the internal spool moves and the connection state of the connection ports A, B, P, R is switched. For example, when the connection port P is connected to the connection port A and the connection port B is connected to the connection port R, the pressure oil discharged from the first hydraulic pump 111 is supplied from the connection port P of the directional control valve 113 through the connection port A to one cylinder chamber of the cylinder case of the blade cylinder 44. This causes the piston in the cylinder case to move. At this time, the pressure oil flowing out from the other cylinder chamber is collected in the hydraulic oil tank 114 through the connection port B of the directional control valve 113 through the connection port R. In this way, when a predetermined pilot pressure is input to the directional control valve 113, the spool of the directional control valve 113 is displaced by the direction and amount specified by the operation lever 101, and pressure oil is supplied to the blade cylinder 44. This allows the blade 41 to move up and down based on the instruction from the operation lever 101 of the operator.

[0045] The configuration of the operating device 100 will be further described. Fig. 6 is a diagram for explaining the configuration of the operating device 100, in which (a) is a rear view of the operating device 100 as seen from the driver's seat 56 side, (b) is a left side view thereof, and (c) is a cross-sectional view taken along the line AA in (a). Fig. 7 shows the relationship between the operation of the operating lever 101 of the operating device 100 and the operating state of the pilot valve 120, in which (a) to (d) show a left side view of the operating device 100 in the upper part and a cross-sectional view taken along the line AA in Fig. 6(a) in the lower part. Fig. 7(a) shows a state in which the operating lever 101 is tilted in a direction to lower the blade 41, (b) shows a state in which the operating lever 101 is in a neutral position where it is not operated, (c) shows a state in which the operating lever 101 is tilted within the dead zone region, and (d) shows a state in which the operating lever 101 is tilted in a direction to raise the blade 41. 8 to 11 are schematic side views for explaining the link structure, reaction force application means, and restriction unit 150 of the operating device 100, and show enlarged views of the link structure, reaction force application means, and restriction unit 150 of the operating device 100. Fig. 8 shows a state in which the operating lever 101 is in a neutral position, Fig. 9 shows a state in which the operating lever 101 is tilted in the dead zone region, Fig. 10 shows a state in which the operating lever 101 is tilted in a direction to raise the blade 41, and Fig. 11 shows a state in which the operating lever 101 is tilted in a direction to lower the blade 41.

[0046] This operating device 100 comprises an operating lever 101, a pilot valve 120 in which a pair of front and rear spool-type valve sections corresponding to the front and rear operation of the operating lever 101 are accommodated in a valve main body 121, and a linkage mechanism which links the operation of the operating lever 101 with the output of the pilot valve 120.

[0047] The operating lever 101 is connected to the pilot valve 120 via a linkage mechanism, which will be described later, so as to be swingable in the front-rear direction.

[0048] In the valve body 121 of the pilot valve 120, there are formed an output port U that outputs pilot pressure to the directional control valve 113, an input port N to which pilot oil pumped from the second hydraulic pump 112 is input, a discharge port D to discharge the pilot oil input from the input port N to the hydraulic oil tank 114, and two substantially cylindrical spool slide holes 124 that communicate with the input port N, the output port U, and the discharge port D. The two spool slide holes 124 are provided parallel to each other and symmetrically in the front-rear direction (the left-right direction in Figs. 6(b) and (c)), and communicate with each other through an oil passage formed between them. In each spool slide hole 124, a spool 125 that connects and disconnects the input port N and the output port U, and the input port N and the discharge port D is slidably provided, and a pressing rod 126 is provided above the spool 125.

[0049] Further, a pressure setting spring 127 and a return spring 128 are provided in the spool sliding hole 124. The pressure setting spring 127 is for determining the pilot pressure and is disposed below the pressing rod 126, with its lower end engaged with a spring seat provided midway in the spool 125. The return spring 128 is for returning the pressing rod 126 and the spool 125 to their initial positions and is provided on the outer circumferential side of the pressure setting spring 127, urging the pressing rod 126 axially upward.

[0050] Provided above the valve main body 121 are a plate-shaped mounting portion 131 that protrudes forward and backward from the valve main body 121, and a plate-shaped tilting portion 135 that protrudes upward and tilts according to the amount of operation of the operating lever 101. Also provided above the valve main body 121 is a pressing rod 126 that is biased upward by a return spring 128 provided in the spool sliding hole 124.

[0051] The tilting part 135 is supported to be able to swing on a support shaft provided between the two spool sliding holes 124 via a pivot 132 whose axis is in the left-right direction. A fixing part 142 of a lever support part 141 that supports the operating lever 101 is fixed to the top surface of the tilting part 135 by screw fastening. The lower surface of the tilting part 135 is connected to the upper end of a pressing rod 126 on the valve body part 121 side via a ball 136. The tilting part 135 tilts in response to the amount of operation of the operating lever 101, thereby pressing the pressing rod 126, and the spool 125 is further displaced by sliding, so that pilot pressure acts on the output port. The outside between the tilting part 135 and the mounting part 131 is covered by a lever boot 137 as a cover member. In the pilot valve 120, the components from the tilting portion 135, which is covered by the lever boot 137 and to which the fixed portion 142 of the lever support portion 141 is fixed, to the spool 125, which slides according to the tilting direction and tilt angle of the tilting portion 135, constitute the control portion 130 that controls the output of the pilot pressure of the pilot valve 120.

[0052] The interlocking mechanism includes a lever support portion 141 that supports the operating lever 101 so as to be able to swing freely, a reaction force imparting means that imparts a reaction force against the swing of the operating lever 101 to the lever support portion 141, and a regulating portion 150 that regulates the application of the reaction force by the compression spring 159 to the operating lever 101. With the reaction force regulated by the regulating portion 150, the operation of the operating lever 101 is transmitted to the control portion 130, thereby interlocking the output of the pilot valve 120 with the operation of the operating lever 101. Furthermore, the interlocking mechanism includes a holder 160 that holds the regulating portion 150.

[0053] The lever support part 141 is made of a metal plate and includes a fixed part 142 fixed by a bolt 149 to the top surface of the tilting part 135 provided above the mounting part 131 of the pilot valve 120, and a support part 143 bent vertically downward from the fixed part 142 and whose plate surface faces in the left-right direction. A shaft 144 protrudes from the support part 143, and the base end part 102 of the operating lever 101 is rotatably supported by the shaft 144. One end of an arm 146 is welded to the base end part 102 of the operating lever 101, and the other end of the arm 146 is pivotally attached to one end of a rod-shaped joint member 147 by a pin 148. The arm 146 and the joint member 147 transmit the amount of operation of the operating lever 101 to the pilot valve 120 by their link structure, and constitute a connecting part according to the present invention.

[0054] The reaction force applying means is a compression spring 159 that can be deformed between a first state in which it is compressed according to the amount of operation of the operating lever 101, and a second state in which the operating lever 101 is operated beyond a predetermined amount of operation. The compression spring 159 is an elastic member in which a metal wire is wound in a coil shape, and its upper and lower ends abut against flanges 154, 155 of a pair of cylindrical bodies 152, 153 described later.

[0055] The interlocking mechanism includes a support 151 whose upper end is connected to a joint member 147 constituting a connecting portion. Threaded portions are provided on both ends of the support 151, and a nut 157 for supporting a lower cylindrical body 153 is screwed into the lower end of the support 151, and a connecting and fixing portion 165 is provided on the upper end of the support 151, and a nut 156 for preventing the upper cylindrical body 152 from coming off upward is screwed into the upper end of the support 151. The connecting and fixing portion 165 is connected to the joint member 147.

[0056] The restricting portion 150 has a pair of upper and lower cylindrical bodies 152, 153 that slidably hold a support 151 therein and are cylindrical members each having a flange 154, 155 at one end. A compression spring 159 is disposed on the outer periphery of the pair of cylindrical bodies 152, 153. The support 151 is inserted into the pair of cylindrical bodies 152, 153, which are disposed with their ends not provided with the flanges 154, 155 facing each other, so that the support 151 can slide relative to the cylindrical bodies 152, 153. A flat washer 158 is interposed between the lower nut 157 and the lower cylindrical body 153, penetrating the support 151. The upper and lower nuts 156, 157 and the flat washer 158 are loosely fitted into a holder 160, which will be described later. As the cylindrical member having a flange, for example, a collar with a flange can be used.

[0057] The pair of cylinders 152, 153 are biased in directions separating from each other by the compression spring 159 abutting against the flanges 154, 155, and are separated from each other with a predetermined length of gap L when the operating lever 101 is not being operated (see FIG. 8). As a result, the amount of displacement (amount of expansion and contraction) of the compression spring 159 is limited to the separation length (size of gap L) of the pair of cylinders 152, 153. The upper cylinder 152 and its flange 154 constitute a first restricting portion, and the lower cylinder 153 and its flange 155 constitute a second restricting portion.

[0058] The holder 160 is a member that transmits the operation of the operating lever 101 to the control unit 130 of the pilot valve 120 by holding both ends of the support 151 inserted into the pair of cylindrical bodies 152, 153. The holder 160 includes a plate-like first holder 161 and a second holder 162 that are protruding from the support part 143 of the lever support part 141. The first holder 161 is formed by bending the lower end of the support part 143 so as to protrude outward from the support part 143. The second holder 162 is formed by bending a metal plate into a substantially L-shape in a side view, and one end is welded to the support part 143. In this way, since the first holder 161 and the second holder 162 are fixed to the lever support part 141, when the lever support part 141 tilts, the first holder 161 and the second holder 162 rotate together.

[0059] The first holder 161 is provided with a notch 163 into which the nut 156 on the upper side of the support 151 movably fits, and the second holder 162 is provided with a hole 164 into which a flat washer provided on the nut 157 on the lower side of the support 151 movably fits. The first holder 161 is disposed parallel to the fixed part 142 of the lever support part 141, and the plate surface of the second holder 162 in which the hole 164 is provided is disposed parallel to the flanges 154, 155. The first holder 161 and the second holder 162 abut against the flanges 154, 155 of the pair of cylindrical bodies 152, 153, respectively, thereby defining the maximum extension of the compression spring 159. The support pillar 151 is inserted through a pair of cylindrical bodies 152, 153 and a compression spring 159, and is movably arranged between a first holder 161 and a second holder 162, so that the support pillar 151 moves linearly along the support axis according to the direction and amount of operation of the operating lever 101.

[0060] In the operating device 100 equipped with the above-described interlocking mechanism, a dead zone is provided in the operating area of ​​the operating lever 101 operated by the operator due to the action of the reaction force imparting means (compression spring 159) and the regulating section 150, in which the blade cylinder 44, which moves the blade 41 of the soil removal device 4 up and down, does not operate.

[0061] When the operating lever 101 is in the neutral position shown in FIG. 7(b) where the operator does not operate the operating lever 101, the spool 125 and the pressure rod 126 of the pilot valve 120 are urged upward by the return spring 128, and the input port N is connected to the discharge port D. Therefore, pilot pressure is not output from the output port U. In addition, in the interlocking mechanism, the flange 154 of the upper cylinder 152 abuts against the first holder 161 and the flange 155 of the lower cylinder 153 abuts against the second holder 162 due to the urging force received from the compression spring 159. Furthermore, a predetermined gap L is formed between the pair of upper and lower cylinders 152, 153 (see FIG. 8).

[0062] When the operator tilts the operating lever 101 to the position shown in FIG. 7(c) which is located behind the driver's seat 56, the base end 102 of the operating lever 101 rotates around the shaft 144 as the operating lever 101 tilts, and the arm 146 fixed to the base end 102 tilts by the same angle as the inclination of the operating lever 101. The tilt of the operating lever 101 is converted into a linear motion of the support 151 by the link structure consisting of the arm 146 and the joint member 147, and the support 151 moves downward. The state of the compression spring 159 at this time is a first state in which it is compressed according to the amount of operation until the gap L between the upper cylinder 152 and the lower cylinder 153 disappears. After that, the upper cylinder 152 and the lower cylinder 153 come into contact with each other. As a result, there is no gap between the upper and lower cylinders 152, 153, and a gap L' is created between the flange 154 of the upper cylinder 152 and the first holder 161 (see FIG. 9). In this way, the operating lever 101 tilts against the reaction force of the compression spring 159 until the upper and lower cylinders 152, 153 come into contact with each other, but the amount of operation of the operating lever 101 is not transmitted to the tilting portion 135 of the pilot valve 120. For this reason, the pilot valve 120 does not output pilot pressure to the directional control valve 113 that controls the blade cylinder 44. Therefore, the operation of the operating lever 101 by the operator from the neutral position shown in FIG. 7(b) to the position shown in FIG. 7(c) corresponds to an operation in the dead zone.

[0063] When the operator operates the control lever 101 in the dead zone, the magnitude of the reaction force that the operator receives from the control lever 101 through the lever support portion 141 is adjusted by the spring constant of the compression spring 159. That is, if the compression spring 159 has a large spring constant, the load that the operator applies to the control lever 101 is also large. In addition, the stroke of the control lever 101 in the dead zone can be adjusted by adjusting the width of the gap L between the pair of cylinders 152, 153. That is, if the gap L between the pair of cylinders 152, 153 is widened, the dead zone also becomes wide. Regarding the rotation range of the control lever 101, the size of the gap between the pair of cylinders 152, 153 is set so that the range in which the gap L between the pair of cylinders 152, 153 exists corresponds to the dead zone of the pilot valve 120.

[0064] When the operator tilts the control lever 101 further backward to the position shown in FIG. 7(d), the movement of the support column 151 is restricted by the second holder 162. At this time, the states of the upper and lower cylinders 152, 153 and the compression spring 159 are maintained in the same state as that shown in FIG. 7(c). The state of the compression spring 159 at this time is the second state in which the control lever 101 is operated beyond a predetermined operation amount, that is, the operation amount in the dead band area. In this way, the flange 155 of the lower cylinder 153 abuts against the second holder 162, and the displacement of the compression spring 159 is regulated by the flanges 154, 155, thereby restricting the movement of the support column 151.

[0065] Furthermore, the spring displacement and load are in a proportional relationship according to Hooke's law (F=kx; F is the load, k is the spring constant, and x is the amount of spring displacement), and by restricting the displacement of the compression spring 159, no further load is applied to the compression spring 159. Then, the force applied to the operating lever 101 acts on the lever support part 141, and the lever support part 141 tilts backward together with the tilt of the operating lever 101 (see FIG. 10). At the same time, the tilting part 135 of the pilot valve 120 also tilts around the pivot 132 and presses the pressing rod 126 via the ball 136 (see FIG. 7(d)). This causes the spool 125 on the valve body part 121 side to move.

[0066] The load applied when the operating lever 101 is swung back and forth is received by the compression spring 159 until it exceeds the reaction force of the compression spring 159, and the load exceeding the reaction force of the compression spring 159 acts on the return spring 128 in the pilot valve 120. The initial compression load of the return spring 128 is equal to or greater than the load when the compression spring 159 is compressed (the reaction force is regulated). The increase in the reaction force per operation amount (lever stroke) of the operating lever 101 differs between when the compression spring 159 is compressed and when the return spring 128 is compressed. Therefore, the operator can recognize that the operating lever 101 has been operated beyond the dead zone to the operating zone from the change in the reaction force from the operating lever 101. The operator can also recognize that the operation is in the operating zone beyond the dead zone from the feeling of collision between the upper and lower cylinders 152, 153 in the regulating part 150.

[0067] When a pressing force is applied to the pressing rod 126, the pressure setting spring 127 and the return spring 128 are compressed and deformed, and the spool 125 is pushed by the pressing rod 126 and slides. As a result, the input port N and the output port U are communicated, and a pilot pressure set by the pressure setting spring 127 is generated in the output port U. Thereafter, the pilot pressure is input to one of the two pilot ports C1, C2 of the directional control valve 113, and hydraulic pressure is supplied to the blade cylinder 44 from the connection port A. This causes the blade cylinder 44 to contract, and the blade 41 to rotate upward.

[0068] 7(d), the pressing force on the pressing rod 126 is released, and the pressing rod 126 and the spool 125 return to their initial positions due to the restoring force of the compressed and deformed return spring 128. The biasing forces acting on the two front and rear pressing rods 126 from the respective return springs 128 provided in the two front and rear spool slide holes 124 are balanced when the operating lever 101 is not being operated, so that the operating lever 101 is held in a neutral position. At the same time, the compression of the compression spring 159 is released, and the pair of upper and lower cylinders 152, 153 are biased by the compression spring 159.

[0069] When the operator tilts the operating lever 101 from the neutral position shown in FIG. 7(b) to the front side shown in FIG. 7(a) which is in front of the driver's seat 56, first, the arm 146 fixed to the base end 102 of the operating lever 101 tilts with the tilt of the operating lever 101, and the support 151 is pulled up via the joint member 147. As a result, the lower nut 157 abuts against the flange 155 of the lower cylinder 153 via the flat washer, and the support 151 moves upward until its movement is restricted by the flange 154 of the upper cylinder 152 abutting against the first holder 161. The state of the compression spring 159 at this time is the first state. Thereafter, the upper cylinder 152 and the lower cylinder 153 come into contact with each other. As a result, there is no gap between the upper and lower cylinders 152, 153, and a gap L' is created between the flange 155 of the lower cylinder 153 and the second holder 162. Next, when the operating lever 101 is further tilted while the movement of the support 151 is restricted by the first holder 161, the lever support part 141 tilts forward accordingly (see FIG. 11). The state of the compression spring 159 at this time is the second state. At the same time, the tilting part 135 also tilts around the pivot 132, and the front pressing rod 126 is pressed via the ball 136 (see FIG. 7(a)).

[0070] The operator tilts the operating lever 101 against the reaction force of the compression spring 159 until the upper cylinder 152 and the lower cylinder 153 come into contact with each other, and then further tilts the operating lever 101. The operator can recognize that the operation range of the operating lever 101 has switched from the dead zone to the operating range from the change in the reaction force acting on the operating lever 101, just as when the operating lever 101 is operated toward the rear of the driver's seat 56.

[0071] When a pressing force is applied to the pressing rod 126, the pressure setting spring 127 and the return spring 128 are compressed and deformed, the spool 125 is pressed by the pressing rod 126 and slides inside the spool sliding hole 124, and the input port N and the output port U are communicated. A pilot pressure set by the pressure setting spring 127 is generated in the output port U. As a result, the pilot pressure is input to one of the two pilot ports C1, C2 of the directional control valve 113, and hydraulic pressure is supplied to the blade cylinder 44 from the connection port B. Thereafter, as the blade cylinder 44 extends, the blade 41 rotates downward.

[0072] As described above, in the operating device 100 of this embodiment, the interlocking mechanism that interlocks the output of the pilot valve 120 with the operation of the operating lever 101 includes a reaction force applying means (compression spring 159) and a regulating portion 150 (cylinder 152 having flange 154, cylinder 153 having flange 155, and nut 157 provided so as to be able to come into contact with flange 155). The interlocking mechanism also includes a connecting portion that connects the end of the operating lever 101 and the support column 151 via a link structure consisting of the arm 146 and the joint member 147.

[0073] In the operating device 100 of this embodiment, the reaction force applying means and the regulating unit 150 provide a dead zone in the operating region of the operating lever 101 so that pilot pressure is not output from the pilot valve 120 when the operator slightly operates the operating lever 101 from the neutral position. The reaction force applying means has a compression spring 159 as a reaction force generating source. The regulating unit has a pair of upper and lower cylinders 152, 153 each having a flange, and a nut 157 slidably inserted into the pair of upper and lower cylinders 152, 153 and provided at the end of the support 151. The regulating unit 150 has a first regulating unit corresponding to one of the swing directions of the operating lever 101, and a second regulating unit corresponding to the other of the swing directions of the operating lever. The first regulating unit is the upper cylinder 152 whose flange 154 is pushed by the nut 156 and moves downward as the support 151 moves when the operating lever 101 is swung backward. The second restricting portion is the lower cylindrical body 153, whose flange 155 is pushed by the nut 157 and moves upward as the support column 151 moves when the operating lever 101 is swung forward.

[0074] The compression spring 159 is deformable in two states: a first state in which it is compressed according to the amount of operation of the operating lever 101, and a second state in which the operating lever 101 is operated beyond a predetermined amount of operation. The first state is a state in which the compression spring 159, which is defined by the gap provided between a pair of upper and lower cylindrical bodies 152, 153 having flanges 154, 155, is compressible. The second state is a state in which the compression spring 159 cannot be further compressed when the pair of upper and lower cylindrical bodies 152, 153 are brought into contact with each other.

[0075] In the first state in which the operating lever 101 is operated and the support column 151 moves to compress the compression spring 159 until the gap between the pair of upper and lower cylinders 152, 153 disappears, a reaction force is applied to the lever support portion 141. Therefore, in the first state, a reaction force acts on the lever support portion 141 in a direction opposite to the displacement direction of the compression spring 159 in response to the operation of the operating lever 101, so the load applied to the operating lever 101 does not act on the lever support portion 141. Since the lever support portion 141 does not tilt, the tilting portion 135 that slides and displaces the spool 125 of the pilot valve 120 does not tilt either, and pilot pressure that operates the directional control valve 113 that supplies hydraulic pressure from the pilot valve 120 to the blade cylinder 44 is not output.

[0076] When the operating lever 101 is operated beyond a predetermined operating amount and there is no gap between the pair of upper and lower cylinders 152, 153, a second state is entered in which the compression spring 159 cannot be further compressed and deformed. In this second state, one of the flanges of the pair of upper and lower cylinders 152, 153 abuts against the first holder 161 and the nut 157, or the second holder 162 and the nut 156, and the sliding of the support 151 between the first holder 161 and the second holder 162 is restricted. In this way, the application of a reaction force to the lever support part 141 is restricted by the first restricting part (flange 154) and the second restricting part (flange 155), so that the reaction force acting on the lever support part 141 in response to the operating load of the operating lever 101 does not increase, and the lever support part 141 tilts in synchronization with the tilting of the operating lever 101. When the lever support portion 141 tilts, the tilting portion 135 that slides and displaces the spool 125 of the pilot valve 120 also tilts, and pilot pressure that operates the directional control valve 113 that supplies hydraulic pressure from the pilot valve 120 to the blade cylinder 44 is output.

[0077] As described above, in the operating device 100 of this embodiment, the pair of cylinders 152, 153 stipulate the deformation range of the compression spring 159, thereby making the dead zone of the operating lever 101 constant. That is, regarding the operating range of the operating lever 101, the range up to the contact between the pair of cylinders 152, 153, that is, the range where a gap exists between the pair of cylinders 152, 153, is the range in which the elastic force of the compression spring 159 acts on the operating lever 101, and corresponds to the dead zone.

[0078] In the operating device 100 of this embodiment, the pilot valve 120 operates according to the characteristics of the spring constant and the like of the return spring 128 and the pressure setting spring 127 arranged in the spool sliding hole 124, while the dead zone is set according to the characteristics of the compression spring 159 provided outside the pilot valve 120. The flanges 154, 155 of the pair of cylindrical bodies 152, 153 restrict the expansion and contraction of the compression spring 159 within a predetermined range, thereby absorbing the variation due to the individual difference in the spring properties of the compression spring 159. This makes it possible to make the dead zone of the operating lever 101 constant. By setting such a dead zone, the timing at which the pilot valve 120 starts moving does not vary due to the individual difference due to the manufacturing variation of the spring inside the pilot valve 120 or the change over time.

[0079] In the operating device 100 of this embodiment, the reaction force imparting means and the regulating unit 150 are configured to be attached to the outside of the pilot valve 120 together with the operating lever 101 by screw fastening via the fixing part 142. Therefore, it is possible to provide an operating device for a work machine having a difference in operability between the dead zone area and the operating area at a low cost by simply removing the operating lever of the existing operating device of the construction machine and attaching the operating lever 101, which is supported by the lever support part 141 and connected to the reaction force imparting means via a link structure, to a pilot valve that is widely used as a component.

[0080] The above-mentioned embodiment is an example of the present invention, and the construction machine according to the present invention is not limited to the above-mentioned embodiment. Therefore, even if it is other than the above-mentioned embodiment, various modifications are possible according to the design, etc., as long as they do not deviate from the technical idea of ​​the present invention. Furthermore, the effects described in this disclosure are merely examples and are not limited, and other effects may be obtained.

[0081] In the above-described embodiment, the compression spring 159 made of metal wire is used as the elastic member constituting the reaction force applying means. However, the elastic member may be, for example, cylindrical rubber, etc., as long as it has a spring constant equal to or greater than a predetermined value.

[0082] In the above-described embodiment, the operating device 100 for moving the blade 41 of the soil removal device 4 up and down has been mainly described, but the operating device in the present invention can be applied as an operating device for other work machines such as a crane device. [Explanation of symbols]

[0083] 1. Excavation machine (construction machine) 4 Earth removal equipment 10 Control section 20A Undercarriage 20B Upper rotating body 30 Support Frame 41 Blade (Blade) 43 Arm 44 Blade Cylinder 100 Operating device 101 Operating lever 102 Proximal end 110 Hydraulic circuit 113 Directional valve 120 Pilot valve 124 Spool sliding hole 125 spool 130 Control section 131 Mounting part 135 Tilt part 141 Lever support part 142 Fixed part 150 Regulatory Department 151 Post 152 Cylinder 153 Cylinder 154 Flange 155 Flange 157 Nut 159 Compression spring (reaction means) 160 Holder 161 First holder part 162 Second holder part

Claims

1. A construction machine equipped with an operating device for operating a directional control valve that controls the flow rate and direction of pressure oil supplied to a hydraulic actuator, The operating device is A swingable operating lever; a pilot valve that outputs a pilot pressure to the directional control valve; a linkage mechanism for linking an output of the pilot valve with the operation of the operating lever; Equipped with The interlocking mechanism includes: a lever support portion connected to a control portion for controlling an output of the pilot pressure of the pilot valve and supporting the operation lever so as to be able to swing; a reaction force applying means for applying a reaction force against the swing of the operating lever to the lever support portion; a restricting portion that restricts an increase in the reaction force applied by the reaction force applying means; wherein the operation of the operating lever is transmitted to the control unit in a state where the increase in the reaction force is regulated by the regulating unit, and the operation of the operating lever cannot be transmitted to the control unit in a state where the increase in the reaction force is not regulated by the regulating unit.

2. The construction machine according to claim 1, characterized in that the reaction force applying means has an elastic member that is deformable between a first state in which it is compressed in accordance with the amount of operation of the operating lever, and a second state in which compression is regulated by the regulating portion when the operating lever is operated beyond a predetermined amount of operation.

3. 3. The construction machine according to claim 2, wherein the interlocking mechanism includes a connecting portion that connects a base end portion of the operating lever and the reaction force applying means via a link structure.

4. 4. The construction machine according to claim 3, wherein the regulating portion has a first regulating portion corresponding to one of the swing directions of the operating lever, and a second regulating portion corresponding to the other of the swing directions of the operating lever.

5. the elastic member in the reaction force applying means is a compression spring, The interlocking mechanism is as follows: A post having an end connected to the connector; a pair of cylindrical members each having a flange at one end thereof against which an end of the compression spring abuts; A construction machine as described in claim 4, characterized in that the first regulating portion is one of the pair of tubular members, the second regulating portion is the other of the pair of tubular members, and the pair of tubular members are spaced apart from each other by the biasing force of the compression spring when the operating lever is not operated.

6. The pilot valve is an output port for outputting the pilot pressure; an input port into which pressure oil pumped from the pressure pump is input; a discharge port for discharging the pressure oil input from the input port into a tank; a spool slide hole communicating with the output port, the input port, and the discharge port; a spool that slides and displaces in the spool slide hole; a tilting portion that tilts in response to an amount of operation of the operating lever and causes the spool to slide and displace; 6. The construction machine according to claim 1, further comprising:

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