JP2007262827A - Autobraking system for wheel loader, and wheel loader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an autobraking method for a wheel loader, which prevents a machine body from being retreated by reaction applied by sediment, when a driver does not use a traveling pedal and when an arm is swung forward for the execution of sediment scooping work, and the wheel loader. <P>SOLUTION: In this autobraking system, when the driver does not use the traveling pedal 110 for performing the traveling operation of the machine body and when the arm 122 is swung, a working fluid supplied to an arm cylinder 137 is partially sent to a main brake, so that the main brake can be actuated for the braking of wheels 4 and 5. The main brake serves as both a traveling brake for also braking the wheels 4 and 5 by making the driver use a brake pedal 109, and an autobrake. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a wheel loader in which a working device that performs work such as scooping or excavation of earth and sand, fertilizer, snow and the like is provided on an airframe supported so as to be able to travel by wheels.

Conventionally, provided with a machine body supported to be able to run by front and rear wheels, and provided with a working device supported at the front part of the machine body, a boom whose base side is supported by the machine body so as to freely swing up and down, There is a wheel loader configured to include an arm pivotally connected to the front end side of the boom so as to be able to swing back and forth, and a working tool swingably provided on the front end side of the arm (see Patent Document 1). .
JP 2005-171608 A

  In the conventional wheel loader, for example, a bucket as a work tool is arranged so as to face the front side, and the back side thereof is pivotally supported on the tip side of the arm so that the bucket can be scooped and dumped. Therefore, when scooping or excavating work objects such as earth and sand, fertilizer, snow, etc., the bucket swing fulcrum is located below the arm swing fulcrum and the bucket bottom is on the ground. When the arm is swung forward from the state where the arm is swung so that the bucket is close to the machine body in the facing work posture, there is an advantage that a large amount of earth and sand is swallowed.

In this case, with the arm swung so that the bucket is close to the airframe, the airframe is moved forward to bring the tip of the bucket close to or in contact with the earth and sand, etc., and the airframe is stopped on the spot to swing the arm forward However, if you start the scooping operation while switching from the travel pedal to the brake pedal when the bucket is scooping, the aircraft will react due to the reaction force from the earth and sand until you release your foot from the travel pedal and depress the brake pedal. There is a problem of retreating.
To solve this problem, it is only necessary to start the scooping operation when the brake pedal is depressed and the brakes are applied, but in this case, a series of work steps from forward to scooping is performed from the traveling pedal to the brake pedal. There is a problem in that workability is reduced due to interruption during replacement.

In addition, it is necessary to confirm that the brake pedal has been depressed and then start the operation of the arm, which causes a problem that the operation becomes complicated and the workability is poor.
In addition, when a bucket as a work tool is pivotally supported on the tip side of the arm so that it can be dumped and dumped, or when other work tools are provided to perform the same operation (when the arm is swung) The same problem occurs when the work tool receives a reaction force from the work object.
Then, an object of this invention is to provide the wheel loader which eliminated the said problem.

The technical means taken by the present invention in order to solve the technical problem includes a machine body supported by a wheel so as to be able to travel and a work device supported by the machine body. And a boom supported pivotably on the tip side of the boom, an arm pivotally connected to the tip end side of the boom, and a work implement provided swingably on the tip end side of the arm. In wheel loader,
The vehicle is braked in conjunction with the swinging of the arm when the traveling operation means for traveling the body is not operated and the arm is swung.

In addition, another technical means includes a machine body supported by a wheel so as to be able to travel and a work device supported by the machine body. The work device includes a boom whose base side is swingably supported by the machine body, A wheel loader comprising: an arm pivotally connected to the tip end side of the boom; and a work implement swingably provided on the tip end side of the arm.
An autobrake system is provided that brakes the wheel by operating a brake in conjunction with the swing of the arm when the arm is swung when the traveling operation means for operating the aircraft is not operated. It is characterized by that.

In addition, a hydraulically operated brake for braking the wheel is provided, and when the traveling operation means is not operated and the arm is swung, a part of the working oil supplied to the arm cylinder that swings the arm is It is preferable that the wheel is braked by being sent to a brake and operating the brake by the hydraulic oil.
In addition, when the travel operation means is not operated in the hydraulic fluid flow path from the arm cylinder side to the brake, the hydraulic oil is allowed to flow from the arm cylinder side to the brake side and when the travel operation means is operated. A first switching valve that interrupts the flow of hydraulic oil from the arm cylinder side to the brake side is interposed, and when the arm swings from the arm cylinder side between the first switching valve and the arm cylinder side. A second switching valve that allows the hydraulic oil to flow to the first switching valve and interrupts the flow of hydraulic oil from the arm cylinder side to the first switching valve when the arm is not swinging may be interposed. Good.

In addition, it is preferable to provide a pressure release circuit for releasing the pressure of the pipe line between the first switching valve and the second switching valve when the travel operation means is operated and the arm is not swinging.
In addition, when the travel operation means is not operated in the hydraulic fluid flow path from the arm cylinder side to the brake, the hydraulic oil is allowed to flow from the arm cylinder side to the brake side and when the travel operation means is operated. A first switching valve that interrupts the flow of hydraulic oil from the arm cylinder side to the brake side is interposed, and when the arm swings, the first switching valve is braked between the first switching valve and the brake. A second switching valve that permits the flow of hydraulic oil to the side and blocks the flow of hydraulic oil from the first switching valve to the brake side when the arm is not swinging may be provided.

The second switching valve is switched by a hydraulic signal sent from a pilot valve that operates an arm control valve for controlling the arm cylinder, or by an electrical signal that is transmitted when an arm operating means that operates the arm is operated. May be.
Further, the second switching valve is constituted by an electromagnetic switching valve, and the second switching for one-way operation of the arm which is switched so as to allow the circulation of the hydraulic oil when the arm operating means is operated so as to swing the arm in one direction. There may be provided a valve and a second switching valve for arm other direction operation that is switched so as to allow the flow of hydraulic oil when the arm operating means is operated to swing the arm in the other direction.

  Further, the brake can be operated by hydraulic oil sent by operation of a traveling system brake operation means operated by an artificial operation during traveling, and hydraulic oil sent by operation of the traveling system brake operation means; Either one of the hydraulic oils sent from the arm cylinder side when the travel operation means is not operated and the arm is swung may be selectively supplied to the brake via the shuttle valve.

  According to the present invention, when the traveling operation means is not operated and the arm is swung, the wheel is braked in conjunction with the swinging of the arm. For example, the operation of the traveling operation means is released. In this state, even if work is started on the work object, the aircraft is prevented from moving due to reaction force from the earth and sand that is the work object, and the series of work flows smoothly and without interruption Work can be performed and workability is improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3, reference numeral 1 denotes an urban-type small wheel loader used for gardening, for example. The wheel loader 1 is roughly composed of a lower traveling body 2 and an upper revolving body 3. ing.
The traveling body 2 is a wheel-type traveling body 2 that can be traveled by a pair of left and right front and rear wheels 4 and 5, and is supported by the pair of left and right front and rear wheels 4 and 5 and the front and rear wheels 4 and 5. A traveling machine body 6, an engine 7 mounted on the traveling machine body 6, a traveling system main power transmission mechanism 8 that transmits power from the engine 7 to the rear wheels 5, and a branch from the traveling system main power transmission mechanism 8. And a front wheel power transmission mechanism 9 for transmitting power to the front wheels 4.

The traveling machine body 6 is mainly composed of a main frame 11 and a front frame 12 provided on the front side of the main frame 11. The main frame 11 includes an engine 7, a radiator 13, a battery 14, a swivel joint 15, a swivel. The front frame 12 is equipped with a fuel tank 18 for storing fuel for the engine 7, and the rear portion of the main frame 11 is supported by the left and right rear wheels 5. The front part is supported by the left and right front wheels 4 and can travel.
The main frame 11 is made of a plate material, and has an upper wall 19, left and right side walls 20 extending downward from left and right side edges of the upper wall 19, and a front fixed to the front ends of the upper wall 19 and the left and right side walls 20. It is mainly composed of a wall 21 and a rear wall 22 that connects rear end lower portions of the left and right side walls 20 and is formed in an open downward shape.

The engine 7 is arranged vertically on the rear side between the left and right side walls 20 of the main frame 11 so that the center of the crankshaft is in the front-rear direction and the output shaft 23 projects forward. The upper end side of the engine 7 protrudes upward from an opening formed in the upper wall 19 of the main frame 11.
A cooling fan 25 is provided at the rear of the engine 7, a radiator 13 is disposed on the left side of the engine 7, and a battery 14 is disposed on the right side of the engine 7.
As shown in FIGS. 4, 7, and 8, the travel system main power transmission mechanism 8 includes a travel propulsion shaft 26 to which power from the engine 7 is transmitted, and a hydrostatic pressure to which power is transmitted from the travel propulsion shaft 26. A transmission (hereinafter referred to as HST) 27, a mechanical transmission means 29 for transmitting the power from the HST 27 to the bevel pinion shaft 28, a rear wheel differential device 30 for transmitting the power from the bevel pinion shaft 28, and the rear wheel And left and right end transmission devices 32 that transmit the power transmitted to the differential device 30 to the left and right rear axles 31, and the traveling propulsion shaft 26, HST 27, mechanical transmission means 29, bevel pinion shaft 28, and rear wheel differential device 30 Is disposed on the front side of the engine 7, and the final transmission device 32 is disposed so as to extend from the side of the rear wheel differential device 30 to the front side of the engine 7.

The travel propulsion shaft 26 is disposed in the front-rear direction on the front side of the engine 7, and the rear end side is connected to a flywheel 33 connected to the output shaft 23 of the engine 7.
The HST 27 includes, in the casing 34, an input shaft 36 for inputting power from the engine 7 and an output shaft 37 for outputting power to the rear wheel differential device 30 so that the shaft centers thereof coincide with each other in the front-rear direction. A hydraulic pump 38 provided on the input shaft 36 and a hydraulic motor 39 provided on the output shaft 37 are accommodated, and the hydraulic motor 39 is driven by hydraulic oil sent from the hydraulic pump 38 driven by the input shaft 36. Thus, the power is output from the output shaft 37 driven by the hydraulic motor 39.

The casing 34 includes a main body 40 having an opening on the rear surface side and a lid body 41 that closes the rear surface side opening of the main body 40, and the input shaft 36 and the output shaft 37 protrude rearward from the lid body 41.
The input shaft 36 of the HST 27 is disposed concentrically with the propulsion shaft 26 on the front side of the travel propulsion shaft 26 and is coupled to the travel propulsion shaft 26 by coupling.
The hydraulic pump 38 is a variable displacement pump, and the swash plate angle can be changed by the swash plate control actuator 42. By changing the swash plate angle, the flow rate of hydraulic oil discharged to the hydraulic motor 39 is changed. Thus, the rotational speed (vehicle speed) of the output shaft 37 can be changed, and the direction of the flow of hydraulic oil discharged to the hydraulic motor 39 is changed to change the rotational direction of the output shaft 37 forward (forward rotation) or reverse ( (Reverse rotation).

  The swash plate control actuator 42 is controlled by a forward / reverse switching means 43 comprising a pilot operation switching servo valve operated by a pilot hydraulic oil. When the pilot operating pressure is established at the forward port 44 of the forward / reverse switching means 43, the swash plate control actuator 42 is output. The swash plate of the hydraulic pump 38 is controlled so that the shaft 37 rotates forward, and the swash plate of the hydraulic pump 38 is controlled so that the output shaft 37 reverses when the pilot operating pressure is applied to the reverse drive port 45. The flow rate of the hydraulic oil discharged from the hydraulic pump 38 is controlled by the degree of pressure at the rearward port 45 or the reverse side port 45, and the rotational speed of the output shaft 37 is controlled.

The hydraulic motor 39 is a variable displacement motor, and the angle of the swash plate can be changed in two stages by the high / low switching actuator 46. By changing the angle of the swash plate, the rotational power output from the output shaft 37 is in a high speed state And can be switched to a low speed state.
The bevel pinion shaft 28 is arranged in parallel to the left side and the lower side of the portion of the output shaft 37 of the HST 27 that protrudes rearward from the lid 41, and extends rearward from the rear end of the output shaft 37 of the HST 27. In addition, a bevel gear portion is formed on the rear end side.
In the present embodiment, the mechanical transmission means 29 includes a drive-side gear 47 that is externally fitted to a portion of the output shaft 37 of the HST 27 that protrudes rearward from the lid 41, and a bevel pinion. It is constituted by a gear transmission mechanism that is externally fitted on the front end side of the shaft 28 so as to be integrally rotatable and is engaged with the drive side gear 47 and is a speed reduction mechanism.

The mechanical transmission means 29 may be a speed increasing mechanism (transmission mechanism) or the same speed mechanism as long as it performs power transmission such as coupling.
The rear wheel differential device 30 is disposed behind the bevel pinion shaft 28 and on the front side on the left side of the engine 7, and projects a differential output shaft 49 on both the left and right sides.
The rear axle 31 is provided at a position behind the differential output shaft 49 of the rear wheel differential device 30 so as to overlap the engine 7 in a side view, and the rear wheels 5 are disposed on the outer end sides of the left and right rear axles 31. The mounting is fixed.

The final transmission device 32 includes a driving gear 51 that is externally fitted to the outer end of the differential output shaft 49 in the left-right direction, and a driven gear 52 that is externally fitted to the rear axle 31 so as to be rotatable. And a speed reduction mechanism.
The final transmission device 32 may be a speed increasing mechanism (transmission mechanism) or the same speed mechanism.
In the traveling system main power transmission mechanism 8 having the above-described configuration, the power output forward from the engine 7 is folded back by the HST 27 and transmitted rearward, and is transmitted to the left and right sides by the rear wheel differential device 30 on the front side of the engine 7. And is transmitted rearward by the final transmission device 32 to reach the rear axle 31, so that the front-rear direction is made compact.

  A housing 53 that accommodates the flywheel 33, the rear wheel differential device 30 and the like is connected and fixed to the front side of the engine 7, and a transmission case 54 that accommodates mechanical transmission means 29 and the like is disposed on the front side of the housing 53. The casing 34 (the cover body 41) of the HST 27 is connected and fixed to the front side of the transmission case 54, and the rear wheel differential device 30, the mechanical transmission means 29, the HST 27, etc. are connected to the engine 7. The housing 53, the transmission case 54, and the casing 34 are disposed between the left and right side walls 20 of the main frame 11.

Further, on both the left and right sides of the housing 53, a final transmission case 55 that houses the final transmission device 32 is fixed. The rear axle 31 is supported by the left and right final transmission cases 55, and the final transmission case 55 is It is fixedly attached to the main frame 11.
The left and right end transmission cases 55 are bolted to the side surfaces of the housing 53 at the front end in the left-right direction, and the rear sides of the left and right end transmission cases 55 are bolted to the upper side of the side wall 20 of the main frame 11. Has been.
On the lower side of the rear part of the left and right side walls 20 of the main frame 11, an open notch 56 is formed below to be fitted to the upper side of the end transmission case 55 from above, and the main part around the notch 56 is formed. A final transmission case 55 is bolted to the frame side wall 20.

The front side of the engine 7 is supported on the main frame 11 via the housing 53 and the final transmission case 55, and the rear side of the engine 7 is supported on the rear wall 22 of the main frame 11 via a connecting plate or the like. Has been.
In the traveling body 2 configured as described above, the rear wheel differential device 30 is provided on the front side of the engine 7, and the rear axle 31 that rotates the rear wheel 5 by the power transmitted from the rear wheel differential device 30 is output as a differential output. The wheel loader 1 is made compact in the front-rear direction by being provided so as to overlap the engine 7 at a position behind the shaft 49 and in a side view.

On the front side of the HST 27, a main pump 58 is attached which is linked to the front end side of the input shaft 36 of the HST 27 and is composed of a dual gear pump driven by the power of the engine 7. The hydraulic oil is supplied to various hydraulic actuators mounted on the wheel loader 1 through the swivel joint 15.
The wheel loader 1 is provided with a sub-pump 59 that is driven by the engine 7 and mainly supplies hydraulic oil for pilot pressure, and the hydraulic oil for pilot pressure from the sub-pump 59 passes through the swivel joint 15 to the wheel loader. 1 and is supplied to the forward / reverse switching means 43 and the like.

In the present embodiment, the oil pan 60 provided on the lower end side of the engine 7 is used as a hydraulic oil tank that stores hydraulic oil for hydraulic equipment.
As shown in FIGS. 4 and 5, the traveling system main power transmission mechanism 8 is transmitted from the HST 27 to the rear wheel differential device 30 and a front wheel differential device 61 to be described later (rear) when traveling or working. A hydraulically operated main brake (traveling brake, autobrake) 62 that brakes traveling power (input to the wheel differential device 30 and the front wheel differential device 61), and the front wheel 4 and the rear wheel 5 are held in a parked state. A hydraulically operated parking brake 63 is provided, and these brakes 62, 63 are arranged behind the drive side gear 47 of the mechanical transmission means 29.

The main brake 62 is accommodated on the transmission case 54 side, a main brake case 64 fixed to the transmission case 54, and a plurality of non-rotatably accommodated in the main brake case 64 that are movable in the front-rear direction. A plate 66, a brake disc 67 disposed between the plates 66, and a main brake piston 68 that press-contacts the brake disc 67 and the plate 66 are provided.
The main brake case 64 is formed to be open rearward, and the rear end side of the output shaft 37 of the HST 27 is inserted into the main brake case 64, and the output shaft 37 inserted into the main brake case 64 is inserted into the main brake case 64. The brake disc 67 is fitted on the rear end side so as to be movable in the axial direction (front-rear direction) and so as to be rotatable together.

The main brake piston 68 is disposed opposite to the front side of the front end plate 66, and is movable in the front-rear direction and can be moved back and forth within a piston opening 69 provided in the main brake case 64. Contained.
The parking brake 63 is disposed on the rear side of the main brake 62, and
The parking brake 63 is disposed in the housing 53 and is fixed to the parking brake case 70, a parking brake piston 71 accommodated in the parking brake case 70, and a piston fixed to the parking brake case 70. A support member 72 and a spring 73 that presses the parking brake piston 71 to press-contact the brake disc 67 and the plate 66 are provided.

The parking brake case 70 is open forward, and the parking brake case 70 is in communication with the main brake case 64.
The piston support member 72 protrudes rearward from the center of the disc portion 74 and is disposed through the rear wall 70a of the parking brake case 70 while being opposed to the plate 66 on the rear end side. The rod part 75 protrudes rearward, and the rod part 75 is fixed to the rear wall 70a of the parking brake case.
The parking brake piston 71 is externally fitted to the piston support member 72 so as to be movable in the front-rear direction.

The spring 73 is accommodated in a spring accommodating portion 76 formed in the parking brake piston 71 so as to be open rearward, and is interposed between the parking brake piston 71 and the rear wall 70a of the parking brake case 70 in a compressed manner. .
In the main brake 62 having the above-described configuration, the operating oil is supplied to the back side of the main brake piston 68 of the piston accommodating portion 69 (the front side of the main brake piston 68 in the illustrated example). When the piston 68 is pressed, the main brake piston 68 moves rearward, and the brake disc 67 and the plate 66 are pressed against the parking brake piston 71 of the parking brake 63, whereby the brake disc 67 and the plate 66 are pressed against each other. The main brake 62 is actuated to brake the output shaft 37 of the HST 27 (the rear wheel 5 and the front wheel 4 are braked).

In the parking brake 63 having the above-described configuration, when the engine 7 is stopped (parking), the spring 73 presses the parking brake piston 71 and presses the brake disc 67 and the plate 66 against the main brake case 64. The brake disc 67 and the plate 66 are pressed against each other, whereby the front wheel 4 and the rear wheel 5 are held in a stopped state.
Further, when the engine 7 is started, the hydraulic oil from the main pump 58 or the sub pump 59 is supplied between the back surface of the disk portion 74 of the piston support member 72 and the parking brake piston 71, and the hydraulic pressure of the hydraulic oil is used. The parking brake piston 71 is moved backward against the urging force of the spring 73, and the pressure contact between the brake disc 67 and the plate 66 is released.

In the brake structure configured as described above, the main brake 62 is constituted by a disc brake, and the brake disc 67 and the plate 66 of this disc brake are also used as the parking brake 63.
A differential lock device 77 is provided on the left side of the rear wheel differential device 30.
As shown in FIG. 4, the differential lock device 77 moves a differential lock shifter 78 that rotates integrally with the left differential output shaft 49 toward the rear wheel differential device 30 against the return spring by hydraulic oil. A hydraulically operated differential lock device 77 that locks differentially by prohibiting the differential action of the rear wheel differential device 30 by engaging the engagement teeth formed on 78 with an engagement tooth provided on the rear wheel differential device 30 side. is there.

A bearing mounting plate 79 made of a thick plate material is provided on the upper surface side of the upper wall 19 at the front portion of the main frame 11, and an outer race of the slewing bearing 17 is mounted and fixed on the bearing mounting plate 79. The center of 17 is the turning axis X.
Further, an inner gear is formed on the inner peripheral side of the inner race of the slewing bearing 17, and a pinion meshed with the inner gear is fixed to the output shaft of the slewing motor 16 including a hydraulic motor fixed to the main frame 11. The inner race of the swing bearing 17 can be driven to rotate about the swing axis X by the swing motor 16.

A swivel joint 15 is disposed concentrically with the pivot axis X at the front portion between the left and right side walls 20 of the main frame 11, and the operation between the traveling body 2 side and the swivel body 3 side is performed via the swivel joint 15. Oil is distributed.
The front frame 12 of the traveling machine body 6 is made of a plate material, and includes an upper wall 81, left and right side walls 82 extending downward from left and right side edges of the upper wall 81, and front portions of the left and right side walls 82. The main part is provided with a connecting plate to be connected, and the rear side is formed open downward.
A front axle case 83 is arranged in the left-right direction on the lower front side of the front frame 12, and front wheel bearings 84 supported by the front frame 12 are arranged on both front and rear sides of the central portion in the left-right direction of the front axle case 83. The front axle case 83 is supported by the front and rear front bearings 84 via a center pin so as to be swingable around the axial center in the front-rear direction. The front wheel 4 is supported so as to be steerable.

On the front side of the front axle case 83, a steering cylinder 85 including a hydraulic cylinder for steering the front wheel 4 is disposed in the left-right direction and is fixedly attached to the front axle case 83. The steering cylinder 85 Are provided with piston rods 87 projecting from the left and right sides of the cylinder tube 86. The left and right piston rods 87 are connected to the front wheel 4 on the same side in the left-right direction. It is controlled by a power steering controller 88 provided on the third side.
A fuel tank 18 that stores fuel for the engine 7 is disposed at a rear portion between the left and right side walls 82 of the front frame 12.

A front wheel power transmission mechanism 9 that transmits power to the front wheels 4 is connected to the driven gear 48 of the mechanical transmission means 29 and protrudes forward from the transmission case 54, and a front axle case 83. A front wheel differential device 61 provided therein, a bevel pinion shaft 90 for inputting power to the front wheel differential device 61, a transmission shaft 91 for interlockingly connecting the bevel pinion shaft 90 and the front wheel power take-out shaft 89, and a front wheel differential An unillustrated final reduction mechanism (transmission mechanism) that transmits power from the differential output shaft 92 of the device 61 to the front wheels 4 is provided.
The revolving unit 3 includes a revolving unit 93 that is supported on the traveling unit 6 so as to be capable of swiveling around a vertical revolving axis, a traveling control device 94, a work device (ground work device, excavation work device) 95, and the like. A driver's seat 96, a control valve 97 for controlling the working device 95 and the turning machine body 93, a counterweight 98 for balancing the weight of the working device 95, a lops 99, and the like are provided.

The traveling machine body 6 and the turning machine body 93 constitute the body of the wheel loader 1.
The swivel body 93 is mounted and fixed to the inner race of the swivel bearing 17 and is turnable about the swivel axis X, and a pair of left and right erected on the front portion of the swivel base 101. It is mainly composed of a mast (working device support) 102 and a driver seat arrangement frame 103 provided at the rear of the swivel base 101.
The driver's seat arrangement frame 103 includes a support frame 104 fixed to the swivel base 101, a seat base 105 that is attached to the support frame 104 and places the driver's seat 96 so that the driver's seat 96 can be moved forward by a front side pivot, and a counterweight. A weight attachment frame 106 to which 98 is attached is provided, and the control valve 97 is attached and fixed to the support frame 104.

The lower end of the front portion of the lops 99 is fixed to the upper end side of the mast 102, and the lower end of the rear portion of the lops 99 is fixed to the weight mounting frame 106.
The traveling system control device 94 includes a steering handle 108 supported by a control table 107 disposed at the center in the left-right direction of the front part of the swivel base (on the front side of the driver's seat 96) and between the pair of left and right masts 102; A brake pedal (travel system brake operation means) 109 and a travel pedal (travel operation means) 110 disposed on the front side of the driver's seat 96 and supported by the swivel base 101 are provided.

The steering handle 108 can operate the power steering controller 88, and the brake pedal 109 is supported at the upper end side so as to be pivotable around the axis center in the left-right direction, and can be stepped on manually. By depressing the brake pedal 109, the hydraulic oil in the master cylinder 111 is supplied to the main brake 62 (the back side of the main brake piston 68 of the piston accommodating portion 69), and the main brake 62 is operated.
The brake pedal 109 is urged to return to the position before the depression by the return spring when the depression is released, and the hydraulic oil supplied to the main brake 62 returns to the master cylinder 111 when the depression is released.

The master cylinder 111 is disposed below the driver's seat 96, and a brake oil tank 112 that stores hydraulic oil for the master cylinder 111 is provided in the vicinity thereof.
The traveling pedal 110 is pivotally supported by a support shaft 113 having a midway portion in the front-rear direction and having a horizontal axis, and can be stepped forward or stepped backward by a human operation as viewed from the driver. It is made possible, and when this front step or rear step is released, it is urged to return to the neutral position.
By depressing the travel pedal 110, a travel remote control valve 114 made of a pilot valve can be operated. The travel remote control valve 114 is operated by the forward port 44 or the reverse travel side of the forward / reverse switching means 43 of the HST 27. By setting the pilot operating pressure at the port 45, the HST 27 is switched between the forward movement state and the reverse movement state, and the traveling speed of the traveling body 2 can be adjusted.

Further, in the pilot oil passages 115a and 115b from the traveling remote control valve 114 to the forward / reverse switching means 43, the forward / backward switching means 43 is switched by the traveling pedal 110 when the swivel base 101 is turned from the forward posture to the backward posture. A forward / reverse switching valve 116 that reverses the operation is interposed.
The forward / reverse conversion switching valve 116 switches the flow of pilot hydraulic oil flowing through the pilot oil passages 115a and 115b between the traveling remote control valve 114 and the forward / reverse switching means 43, and the pilot hydraulic oil from the traveling remote control valve 114 is switched. Is constituted by a four-port three-position switching valve capable of supplying the forward / reverse switching means 43.

In the state where the forward / reverse switching valve 116 is switched to the A position, the pilot hydraulic oil from the traveling remote control valve 114 is supplied to the forward-side port 44 of the forward / reverse switching means 43 when the traveling pedal 110 is stepped forward. By depressing the pedal 110 backward, hydraulic oil from the travel remote control valve 114 is supplied to the reverse port 45 of the forward / reverse switching means 43. By depressing the travel pedal 110 forward, the traveling body 2 moves forward and travels. By depressing the pedal 110 to the rear side, the traveling body 2 moves backward.
Further, in the state where the forward / reverse switching valve 116 is switched to the B position, the supply of pilot hydraulic oil from the traveling remote control valve 114 to the forward / reverse switching means 43 is cut off. The traveling body 2 cannot be traveled by operation.

Further, in a state where the forward / reverse switching valve 116 is switched to the C position, hydraulic oil from the traveling remote control valve 114 is supplied to the backward port 45 of the forward / reverse switching means 43 when the traveling pedal 110 is stepped forward, The hydraulic fluid from the travel remote control valve 114 is supplied to the forward port 44 of the forward / reverse switching means 43 by depressing the rear 110, and the travel body 2 moves backward by depressing the travel pedal 110 to the front. The traveling body 2 moves forward by stepping 110 forward.
The forward / reverse switching valve 116 is switched to the A position when the swing machine body 93 is in the forward posture, is switched to the C position when the swing machine body 93 is in the backward posture, and B when the swing machine body 93 is in the horizontal posture. Switch to position.

Therefore, when the turning machine body 93 is in the forward posture, the traveling body 2 moves forward by depressing the traveling pedal 110 forward, and the traveling body 2 moves backward by depressing the traveling pedal 110 rearward. When the revolving machine body 93 is in the rearward posture, the traveling body 2 moves backward by depressing the traveling pedal 110 forward, the traveling body 2 moves forward by depressing the traveling pedal 110 rearward, and the revolving machine body. When 93 is in the horizontal posture, the traveling body 2 cannot travel.
In addition, in the hydraulic fluid distribution path from the power steering controller 88 to the steering cylinder 85, the driving seated on the driver's seat 96 regardless of whether the revolving machine body 93 is in the forward posture or the backward posture. A steering conversion means 117 is provided for switching the flow of hydraulic oil so that the direction in which the steering wheel 108 is turned and the turning direction of the traveling body 2 coincide with each other as viewed from the user.

The steering conversion means 117 is in a neutral state when the turning machine body 93 is in the horizontal direction, and the traveling body 2 cannot be steered regardless of the operation of the steering handle 108.
As shown in FIGS. 1 and 6, the working device 95 is pivotally connected to an attachment member 118 and an upper portion of the attachment member 118 so that the base side can pivot about a horizontal axis through a boom support shaft 119. A pair of left and right arms 120 and a pair of arms 122 whose base side is pivotally connected to the distal end side of the boom 120 via an arm support shaft 121 so as to be pivotable about the left and right axes are provided. Two buckets 123.

The left and right attachment members 118 are detachably attached to the mast 102 on the same side in the left-right direction via upper and lower connection pins, and the middle portions in the longitudinal direction of the left and right booms 120 and the bases of the left and right arms 122 are connected to each other. The members 124 and 125 are connected.
The bucket 123 is provided across the left and right arms 122 on the distal end side of the left and right arms 122 and has a left and right width that protrudes outward from the left and right arms 122 in the left and right directions.
Further, the bucket 123 shown in the figure performs grounding work such as rake work such as earth and sand, fertilizer, and snow and excavation work, and includes a bottom wall part 126, a back wall part 127, and left and right side wall parts 128. Thus, the back side is detachably attached to the attachment body 129 provided on the distal end side of the arm 122 so that the opening portion faces the front side with the bottom face facing the ground.

The attachment body 129 is pivotally connected to the distal end side of the arm 122 via a bucket support shaft 130 so as to be rotatable about a horizontal axis.
One end side of the first link 131 is pivotally connected to the attachment body 129 via a pivot 132 so as to be rotatable around a horizontal axis. The second link 133 is connected to the other end side of the first link 131. One end of the second link 133 is pivotally connected via a connecting shaft 134 so as to be pivotable around the left and right axial centers. The other end of the second link 133 is on the distal end side of the arm 122 and opposite to the bucket support shaft 130. Closely pivotally connected to the left and right axial centers via a horizontal shaft 135.

Boom cylinders 136 are respectively disposed below the base side (rear side) of each of the left and right booms 120. One end side of the boom cylinder 136 is pivotally connected to the lower part of the mounting member 118, and the other end side is a boom. The boom 120 is pivotally connected to a middle portion in the longitudinal direction on the lower surface side of the 120. By extending and contracting the boom cylinder 136, the boom 120 swings around the boom support shaft 119 and is raised and lowered.
Arm cylinders 137 are respectively arranged on the upper side of the front end side (front side) of the boom 120, and one end side of the arm cylinder 137 is pivotally connected to the middle part in the longitudinal direction on the upper surface side of the boom 120. Is pivotally connected to the base side of the arm 122. When the arm cylinder 137 is extended and contracted, the arm 122 swings around the arm support shaft 121 and swings forward and backward.

One bucket cylinder 138 is disposed between the left and right arms 122, one end side of the bucket cylinder 138 is pivotally connected to a connecting member 125 that connects the base side of the left and right arms 122, and the other end side is the first side. The link 131 and the second link 133 are pivotally connected to each other via the connecting shaft 134. By extending and contracting the bucket cylinder 138, the bucket 123 swings around the bucket support shaft 130. Performs dumping (downward swing) and scooping (upward swing).
The boom cylinder 136, the arm cylinder 137 and the bucket cylinder 138 are constituted by hydraulic cylinders.

As shown in FIGS. 1 and 6, the attachment body 129 for attaching and supporting the bucket 123 has a swing support point (bucket support shaft 130) of the bucket 123 below a swing support point (arm support shaft 121) of the arm 122. In a working posture in which the bottom surface of the bucket 123 faces the ground, the swinging fulcrum 130 of the bucket 123 is pivotally connected to the distal end side of the arm 122 so as to be positioned on the lower side of the back side of the bucket 123. ing.
Further, the arm 122 is bent so as to protrude in the direction away from the bucket 123 in the middle in the longitudinal direction, and the longitudinal edge 122a on the front side of the arm 122 is formed on the longitudinal edge 122a. The arm 122 is bent so as to be positioned rearward of the tangent line 140 that contacts the upper side and the lower side, and the bucket 123 is moved in the middle in the longitudinal direction on the front side of the arm 122 (upward swinging operation). ), An interference avoidance space 141 is provided to avoid interference with the rear upper end side of the bucket 123.

  In other words, in other words, the swing fulcrum 130 of the bucket 123 is located below the swing fulcrum 121 of the arm 122, the bottom surface of the bucket 123 is opposed to the ground, and the bucket 123 is the body of the wheel loader 1. In a working posture in which the arm 122 is swung so as to be close to each other, the swing fulcrum 130 of the bucket 123 is configured to be positioned on the lower side on the back side of the bucket 123, and the arm 122 has a longitudinal direction thereof. The upper side of the arm 122 is inclined to move backward and the lower side in the longitudinal direction of the arm 122 is substantially hanging (vertically downward, or inclined to move backward or forward as it goes downward, and the arm 122 is bent so as to have an inclination angle smaller than the inclination angle with respect to the vertical direction on the upper side.

In addition, the lower side of the arm 122 below the bent portion 139 of the arm 122 may be formed in a linear shape or a curved shape.
According to the above configuration, the swing fulcrum 130 of the bucket 123 is in the working posture in which the swing fulcrum 130 of the bucket 123 is located below the swing fulcrum 121 of the arm 122 and the bottom surface of the bucket 123 faces the ground. Since it is configured to be positioned on the lower side of the back side of the bucket 123, for example, when the arm 122 is swung forward and the tip end side of the bucket 123 is pierced against earth and the like, the bucket 123 Escape to the back side is prevented, and the leading end side of the bucket 123 pierces the earth and sand well.

  Further, in the configuration in which the swing fulcrum 130 of the bucket 123 is positioned at the lower part on the back side of the bucket 123, if the arm 122 is linear from one end to the other end, the bucket 123 swings. In a working posture in which the moving fulcrum 130 is located below the swing fulcrum 121 of the arm 122 and the bottom surface of the bucket 123 faces the ground, the arm 122 is swung rearward to bring the bucket 123 close to the body of the wheel loader 1. Since the upper end of the back surface of the bucket 123 is close to the arm 122 when it is operated, the bucket 123 cannot be brought too close to the airframe in order to secure the space between the upper end of the back surface of the bucket 123 and the arm 122. In the form, the arm 122 is convex in the direction away from the bucket 123 in the middle in the longitudinal direction. Since the bend is formed (the interference avoidance space 141 is formed in the middle part of the front edge side of the arm 122), when the arm 122 is swung back and the bucket 123 is brought close to the airframe, the arm 122 and the bucket A sufficient distance can be secured between the upper end of the rear surface of 123 and the swinging fulcrum 130 of the bucket 123 is positioned at the lower portion on the rear side of the bucket 123 so that the bucket 123 can be brought close to the airframe. In addition, since the bucket 123 can be brought close to the airframe, a sufficient stroke in the front-rear direction of the bucket 123 can be secured, and the bucket 123 can be shaken when the bucket 123 is swung while the bucket 123 is close to the airframe. Increase the moving angle (the angle formed by the bottom surface of the bucket 123 and the ground) (ensure enough). It can be.

In the present embodiment, the bucket 123 is attached to the bucket 123 capable of scooping and dumping, but the bucket is capable of being scraped and dumped with the opening portion facing rearward with the bottom face facing the ground. 123 may be attached, and other work tools may be attached instead of the bucket 123.
Further, a bucket is supported on a support body attached to the front end side of the left and right arms so as to be rotatable about an axis perpendicular to the bucket support surface, and the bucket is supported by a hydraulic actuator. It may be possible to change the posture from the first working posture capable of scooping work to the second working posture capable of scraping work by turning 180 ° around the pivot axis.

On the left and right sides of the driver's seat 96, operating levers (operating system operating means) 146 for operating the working device 95 and the turning machine body 93 are arranged.
As shown in FIG. 7, in the present embodiment, the left and right operation levers 146 are configured such that the left operation lever 146 operates the swivel base 101 and the arm 122 (arm operation means), and the right operation lever 146 includes the right operation lever 146. The boom 120 and the bucket 123 are operated.
The control valve 97 is attached to a bucket control valve V1 that controls the bucket cylinder 138, a boom control valve V2 that controls the boom cylinder 136, and a bucket that is freely changeable in a scooping posture and a scraping posture. In this case, the bucket rotation control valve V3 for controlling the hydraulic actuator for rotating the bucket, the arm control valve V4 for controlling the arm cylinder 137, and the turning control valve V5 for controlling the turning motor 16 are integrated. Each control valve comprising a direct acting spool type switching valve is connected in a direction orthogonal to the sliding direction of the spool, and the hydraulic oil from the main pump 58 is controlled via the swivel joint 15. Each control valve V1 to V5 of the control valve 97 is supplied with each valve. It is sent to the Chueta.

The bucket control valve V1, the boom control valve V2, the arm control valve V4, and the turning control valve V5 are constituted by pilot operation switching valves that are switched by pilot hydraulic oil, and the bucket turning control valve V3 is turned. It is constituted by a manual switching valve that is switched by a switching lever provided in the airframe 93.
The left operation lever 146 is attached to the arm / swing remote control valve 147 including a pilot valve for controlling the arm control valve V4 and the swing control valve V5, and the right operation lever 146 is connected to the boom control valve V2. It is attached to a boom / bucket remote control valve 148 comprising a pilot valve for controlling the bucket control valve V 1, and the remote control valves 147 and 148 can be operated by the operation lever 146.

In this embodiment, for example, by swinging the left operation lever 146 back and forth, the arm control valve V4 is operated and the arm 122 swings forward and backward, and the left operation lever By swinging 146 left and right, the turning control valve V5 is operated, and the turning machine body 93 turns left and right.
Further, by swinging the right operation lever 146 back and forth, the boom control valve V2 is operated to lower and raise the boom 120, and by swinging the right operation lever 146 left and right, the bucket The control valve V1 is operated, and the bucket 123 is dumped and scooped.

  By the way, in the case of a wheel loader that is pivotally supported so that the bucket can be scooped and dumped at the tip side of the arm, when the work object such as earth and sand, fertilizer and snow is removed, the swing fulcrum of the bucket is In a working posture that is located below the swing fulcrum of the bucket and the bottom surface of the bucket faces the ground, the bucket is swung forward while the arm is swung forward so that the bucket is close to the machine body. In the case of scooping operation, with the arm swung so that the bucket is close to the aircraft, the aircraft is advanced to bring the tip of the bucket close to or in contact with earth and sand, etc., and the aircraft is stopped on the spot to move the arm forward If you start the scooping operation while switching from the travel pedal to the brake pedal when swinging the bucket while swinging, the brake pedal will be released. Until stepping on, there is a problem that the aircraft will be retracted by the reaction force from the earth and sand.

Therefore, in the wheel loader 1 according to the present embodiment, as shown in FIGS. 9 to 15, when the traveling pedal 110 is not operated and the arm 122 is swung, the arm 122 is swung. The automatic brake system 150 that brakes the wheels 4 and 5 in conjunction with the vehicle is provided.
9 and 10, when the traveling pedal 110 is not depressed (not operated) and the arm 122 is swung, a part of the hydraulic oil supplied to the arm cylinder 137 is the main brake system 150. The wheels 4 and 5 (front and rear wheels 4 and 5) are braked by being sent to the brake 62 and operating the main brake 62 by the hydraulic oil.

Therefore, in the wheel loader of the present embodiment, the main brake 62 swings the arm 122 while not operating the traveling pedal 110 and the traveling brake that brakes the wheels 4 and 5 by depressing the brake pedal 109. It is also used as an autobrake that brakes the wheels 4 and 5 in conjunction with the swing of the arm 122 when it is moved.
The traveling brake and the auto brake may be provided independently, and the auto brake is not limited to a hydraulically operated brake, and may be a mechanically operated brake or a disc. Even if it is not a brake, it may be constituted by a drum brake or other type of brake.

The auto brake system 150 shown in FIGS. 9 and 10 will be described in detail. The pressure of the hydraulic oil supplied from the main pump 58 supplied to the bottom side or the rod side of the arm cylinder 137 via the arm control valve V4. A first shuttle valve 151 for selectively sending a part of the higher hydraulic oil to the main brake 62 side;
A pressure reducing valve 152 for depressurizing the hydraulic oil from the first shuttle valve 151 and sending it to the main brake 62 side;
When the travel pedal 110 is not operated, a communication position 153a that allows the hydraulic oil to flow from the pressure reducing valve 152 (arm cylinder 137 side) to the main brake 62 side, and when the travel pedal 110 is operated, the pressure reducing valve 152 (arm cylinder) A first switching valve 153 switchable to a shut-off position 153b for shutting off the flow of hydraulic oil from the 137 side) to the main brake 62 side;
It is interposed in the hydraulic fluid flow path between the first switching valve 153 and the pressure reducing valve 152 (arm cylinder 137 side), and when the arm 122 swings, the pressure reducing valve 152 (arm cylinder 137 side) first A communication position 154a that allows the flow of hydraulic oil to the switching valve 153, and a block that blocks the flow of hydraulic oil from the pressure reducing valve 152 (arm cylinder 137 side) to the first switching valve 153 when the arm 122 is not rocked. A second switching valve 154 switchable to position 154b;
Hydraulic oil sent from the master cylinder 111 (brake pedal 109 side) and hydraulic oil sent from the first switching valve 153 (arm cylinder 137 side) when the travel pedal 110 is not operated and the arm 122 is swung. And a second shuttle valve 155 that can selectively supply hydraulic oil to one of the main brakes 62 (which has a higher pressure).

  The first switching valve 153 is configured by an electromagnetic switching valve that is urged in a direction to be switched to the cutoff position 153b by a spring 156 and switched to the communication position 153a by an electric signal (ON signal), and the travel pedal 110 is depressed. For example, when the travel sensor 157 including a limit switch that detects whether or not the travel pedal 110 is depressed is turned off (an OFF signal is transmitted to the first switching valve 153), for example. When the switching valve 153 is demagnetized and the first switching valve 153 is switched to the shut-off position 153b and the traveling pedal 110 is not depressed, the traveling sensor 157 is turned on (the first switching valve 153 has an ON signal). The first switching valve 153 is excited and the first switching valve 153 is switched to the communication position 153a.

  The second switching valve 154 is configured by an electromagnetic switching valve that is biased in a direction to be switched to the cutoff position 154b by a spring 158 and switched to the communication position 154a by an electric signal (ON signal), and the arm 122 swings. If not, for example, an arm sensor 159 such as a limit switch for detecting whether or not the arm operating lever 146 is operated is turned off, the second switching valve 154 is demagnetized, and the second switching is performed. When the valve 154 is switched to the shut-off position 154b and the arm 122 is swinging, the arm sensor 159 is turned on, the second switching valve 154 is excited, and the second switching valve 154 is moved to the communication position 154a. Can be switched.

  In the automatic brake system 150 having the above-described configuration, for example, when performing a scooping operation such as earth and sand, the swing fulcrum 130 of the bucket 123 is positioned below the swing fulcrum 121 of the arm 122 and the bottom surface of the bucket 123. From the working posture shown in FIG. 1 in which the arm 122 is swung so that the bucket 123 is close to the airframe, and the wheel loader 1 is moved forward to bring the tip of the bucket 123 close to or in contact with earth and sand, etc. When the operation of depressing the travel pedal 110 is released to stop the forward travel and the bucket 123 is swung forward while swinging the arm 122 forward, as shown in FIG. 2 The switching valve 154 is switched to the communication positions 153a and 154a, respectively, and is supplied to the rod side of the arm cylinder 137. Part of the main brake 62 through the first shuttle valve 151 → the pressure reducing valve 152 → the communication oil path 175 of the second switching valve 154 → the communication oil path 162 of the first switching valve 153 → the second shuttle valve 155. It is supplied to the back side of the main brake piston 68 of the part 69, and the main brake 62 is operated to brake the wheels 4 and 5.

Thus, even when the bucket 123 is scooped forward while the arm 122 is swung forward, the wheel loader 1 does not move backward due to the reaction force from the earth and sand even if the foot is released from the traveling pedal 110, and the forward movement → It is possible to smoothly carry out scooping work such as earth and sand without interrupting the flow of a series of operations called scooping.
Further, when the traveling pedal 110 is depressed while the arm 122 is swinging, as shown in FIG. 10B, the first switching valve 153 is switched to the cutoff position 153b, and a part of the hydraulic oil supplied to the arm cylinder 137 is obtained. The flow to the main brake 62 side is blocked by the first switching valve 153, and the hydraulic oil in the piston accommodating portion 69 of the main brake 62 flows from the second shuttle valve 155 to the drain oil passage 160 of the first switching valve 153 → The tank drains through the drain circuit 161 from the first switching valve 153 to the hydraulic oil tank (oil pan) 60, and the braking of the wheels 4 and 5 is released.

Accordingly, the main brake 62 does not operate even when the arm 122 is swung during traveling.
When the swinging of the arm 122 is stopped in a state where the depression of the travel pedal 110 is released, the second switching valve 154 is switched to the cutoff position 154b as shown in FIG. The hydraulic oil in the piston accommodating portion 69 of the second shuttle valve 155 → the communication oil path 162 of the first switching valve 153 → the pipe line 163 → the second switching valve 154 between the first switching valve 153 and the second switching valve 154 Drain oil passage 164 of valve 154 → tank drain through a drain circuit 165 extending from second switching valve 154 to hydraulic oil tank (oil pan) 60, and braking of wheels 4 and 5 is released.

  In the autobrake system 150 having the above-described configuration, when the swing of the arm 122 is stopped in a state where the travel pedal 110 is depressed and the arm 122 is swung as shown in FIG. A pipe line 163 between the first switching valve 153 and the second switching valve 154 communicates with the hydraulic oil tank 60 via the drain oil path 164 of the second switching valve 154 and the drain circuit 165, and the first switching valve 153. No confining pressure remains in the pipe line 163 between the second switching valve 154 (if there is confining pressure, the depression of the traveling pedal 110 is released when the arm 122 is not rocking and during traveling. In this case, the closing pressure acts on the main brake 62 and a braking force is applied to the wheels 4 and 5 to receive a shock).

By the drain oil passage 164 and the drain circuit 165 of the second switching valve 154, when the travel pedal 110 is operated and the arm 122 is not swinging, the first switching valve 153 and the second switching valve 154 are not connected. A pressure release circuit for releasing the pressure of the pipe line 163 is configured.
If the brake pedal 109 is depressed when the travel pedal 110 is not depressed, hydraulic oil (brake oil) is supplied from the master cylinder 111 to the main brake 62 via the second shuttle valve 155, and the main brake 62 is activated. .
In the autobrake system 150 configured as described above, the first switching valve 153 may be configured to be switched to the communication position 153a by a spring when demagnetized and switched to the blocking position 153b when energized. The second switching valve 154 may be configured to be switched to the communication position 154a by a spring when demagnetized and switched to the cutoff position 154b when excited.

Further, the second switching valve 154 may be interposed in the hydraulic oil flow path between the first switching valve 153 and the second shuttle valve 155.
Furthermore, the first switching valve 153 and / or the second switching valve 154 may be configured by a pilot operation switching valve operated by pilot hydraulic oil. In this case, for example, the first switching valve 153 is a pilot operation switching valve. In the case of the configuration, when the travel pedal 110 is depressed, the first switching valve 153 is switched to the shut-off position 153b by the pilot hydraulic oil from the travel remote control valve 114, and when the travel pedal 110 is not depressed, the first is operated by the spring. In the case where the first switching valve 153 is configured to be switched to the communication position 153a and the second switching valve 154 is configured by a pilot operation switching valve, when the arm operating lever 146 is operated, The second switching valve 154 is communicated with the pilot hydraulic oil from the remote control valve 147 It is switched to 54a, configured so that the second switching valve 154 by a spring is switched to the cutoff position 154b when not operating the operation lever 146 for arm operation.

In the automatic brake system 150 having the above-described configuration, the operation supplied to the arm cylinder 137 in conjunction with the swing of the arm 122 when the travel pedal 110 is not operated and the arm 122 is swung. A part of the oil is configured to be supplied to the main brake 62 (auto brake). However, the present invention is not limited to this, and the main brake is started from an appropriate place in the supply circuit of the hydraulic oil discharged from the main pump 58. 62 may be configured to be sent.
The pilot hydraulic oil from the arm / swing remote control valve 147 that controls the arm control valve V4 or the pilot hydraulic oil from the arm / swing remote control valve 147 to the arm / swing remote control valve 147 is not operated. The operating oil may be used to operate the main brake 62 when the arm 122 is swung.

In addition, design changes that can be applied to the embodiments described below can be similarly changed.
The autobrake system 150 shown in FIG. 11A is configured so that the second switching valve 154 composed of the electromagnetic switching valve described above is connected in parallel to the hydraulic oil flow path from the pressure reducing valve 152 (arm cylinder 137 side) to the first switching valve 153. The hydraulic oil that has passed through the second switching valve 154 that has been excited and switched to the communication position 154a among the two second switching valves 154 is sent to the first switching valve 153. 9 is different from the above-described autobrake system 150 in that a third shuttle valve 166 is provided, and the other configuration is substantially the same as the autobrake system 150 shown in FIG.

Of the two second switching valves 154, one second switching valve 154 is excited when the arm operating means is operated so as to swing the arm 122 in one direction and is switched to the communication position 154a. A second switching valve 154 for direction operation is provided, and the other second switching valve 154 is an arm that is excited and switched to the communication position 154a when the arm operating means is operated to swing the arm 122 in the other direction. The second switching valve 154 for operation in the other direction is used.
As the arm operation means, for example, an operation button for extending the arm cylinder 137 and an operation button for contracting the arm cylinder 137 are provided, and the arm / turning remote control valve 147 is operated by pressing these operation buttons. The operation means adapted to do this is employed, one of the second switching valves 154 is excited by the switch 167 that is turned on when one of the operation buttons is pressed, and the other is turned on by the switch 168 that is turned on when the other operation button is pressed. When the second switching valve 154 is excited and the operation button is released, the switches 167 and 168 are turned off and the second switching valve 154 is demagnetized.

In addition, when an operation button for extending the arm cylinder 137 and an operation button for contracting the arm cylinder 137 are provided, and the arm 122 is swung by pressing the operation buttons, the arm control valve V4 is The arm control valve V4 may be configured by an electromagnetic switching valve and controlled by an electric signal generated by pressing the operation button.
Further, the autobrake system 150 shown in FIG. 11B eliminates the first shuttle valve 151 and includes a pressure reducing valve 152 in the hydraulic oil flow path between the first switching valve 153 and the third shuttle valve 166. This is different from the autobrake system 150 shown in FIG. 11A in other respects, and other configurations are the same as the autobrake system 150 shown in FIG.

In the autobrake system 150 shown in FIG. 11, a detection sensor such as a limit switch for detecting the operation when the operation lever 146 for arm operation described above is swung in one direction, and the operation lever 146. And a detection sensor such as a limit switch for detecting the operation when swung in the other direction, the one switching valve 154 is switched by the detection signal of one detection sensor, and the detection of the other detection sensor is performed. The other second switching valve 154 may be switched by a signal.
In the autobrake system 150 shown in FIG. 12A, a pilot check valve is employed as the second switching valve 154 in the autobrake system 150 shown in FIG. 9, and the pilot check valve 154 is replaced with the first switching valve 153. Two systems that intervene in the hydraulic fluid flow path between the second shuttle valve 155 and are sent from the arm / swing remote control valve 147 to the arm control valve V4 (for arm cylinder extension and for arm cylinder contraction) 9 is different from the autobrake system 150 shown in FIG. 9 in that a third shuttle valve 169 for sending pilot hydraulic oil on the high pressure side of the pilot hydraulic oil to the second switching valve 154 is provided. It is constituted similarly.

  In this autobrake system 150, when the arm operating lever 146 is not operated, the second switching valve 154 is closed, and the arm 122 is swung without depressing the travel pedal 110. Sometimes, the first switching valve 153 is excited and switched to the communication position 153a, and the second switching valve 154 is opened by the pilot hydraulic oil from the arm / swing remote control valve 147, and the hydraulic oil supplied to the arm cylinder 137 A part is sent to the first switching valve 153 via the pressure reducing valve 152, passes through the first switching valve 153 and the second switching valve 154, and sent to the main brake 62 via the second shuttle valve 155. The wheels 4 and 5 are braked.

Further, in this automatic brake system 150, when the travel pedal 110 is depressed when the arm 122 is not swinging, the second shuttle valve 155 → the second switching valve 154 → the first switching valve 153 from the main brake 62. The hydraulic oil is drained through the drain oil passage 160 → the drain circuit 161, and the operation of the main brake 62 is released.
Further, the autobrake system 150 shown in FIG. 12B has the second changeover valve 154 interposed in the hydraulic oil flow path between the pressure reducing valve 152 and the first changeover valve 153 as shown in FIG. Unlike the auto brake system 150 shown in FIG. 12A, other configurations are the same as those of the auto brake system 150 shown in FIG.

In the autobrake system 150, when the travel pedal 110 is depressed when the arm 122 is swung, a closing pressure is generated in the pipe line 163 between the first switching valve 153 and the second switching valve 154, so that the pilot The second switching valve 154 composed of a check valve is preferably interposed between the first switching valve 153 and the second shuttle valve 155.
The autobrake system 150 shown in FIG. 13 (a) is constituted by a pilot operation switching valve that can be switched by a pilot operating pressure in the second switching valve 154 in the autobrake system 150 shown in FIG. A third shuttle valve 180 for sending high-pressure side pilot hydraulic fluid from the second switching valve 154 is provided, and the second switching valve 154 is switched to the communication position 154a by the pilot hydraulic fluid from the arm / swing remote control valve 147. The other configuration is substantially the same as that of the autobrake system 150 shown in FIG.

  The autobrake system 150 shown in FIG. 13 (b) has a third oil passage 170 interposed between the third shuttle valve 169 and the second switching valve 154 of the autobrake system 150 in FIG. 12 (b). A first drain oil passage 194 that includes a switching valve 171 and allows the hydraulic oil from the auto brake to flow to the drain circuit 161 when the first switching valve 153 is switched by the spring 156 when the travel pedal 110 is operated. And a second drain oil passage 195 for releasing the pressure of the pipe line 163 between the first switching valve 153 and the second switching valve 154 to the drain circuit 161 through the drain pipe line 172. 12 is different from the auto brake system 150 shown in FIG. 12B, and other configurations are substantially the same as those of the auto brake system 150 shown in FIG. It is configured as.

The third switching valve 171 is composed of an electromagnetic switching valve. When the traveling pedal 110 is not depressed, the third switching valve 171 is switched to a communication position 171a that allows the flow of pilot hydraulic fluid when excited, and the traveling pedal 110 is moved. When the pedal is depressed, the spring 173 switches to a blocking position 171b that blocks the flow of the pilot hydraulic oil 170 by being demagnetized.
In the autobrake system 150, when the travel pedal 110 is operated and the arm 122 is not swinging, a confining pressure is applied to the pipe line 163 between the first switching valve 153 and the second switching valve 154. Does not occur.

  The automatic brake system 150 shown in FIG. 14A is a remote control valve for traveling when the first switching valve 153 in the automatic brake system 150 shown in FIG. 12A is depressed forward or backward. The pilot operation oil is supplied from the traveling remote control valve 114 when the travel pedal 110 is stepped forward or rearward. The fourth shuttle valve 174 for sending to the first switching valve 153 is provided, and the other configuration is the same as that of the autobrake system 150 shown in FIG.

In this automatic brake system 150, when the travel pedal 110 is not depressed, pilot operating pressure does not act on the first switching valve 153, so that the first switching valve 153 is switched to the communication position 153a by the spring 156. It is configured to be.
The auto brake system 150 shown in FIG. 14B is a master cylinder that sends hydraulic oil to an auto brake (which may be the main brake 62 serving also as the traveling brake described above or a brake dedicated to the auto brake system 150). 176, auto brake cylinder 177, and part of the pilot hydraulic fluid (high pressure side) from travel remote control valve 114 is sent to the bottom side of auto brake cylinder 177 when travel pedal 110 is depressed forward or backward. Part of the pilot hydraulic fluid sent from the arm / swing remote control valve 147 to the arm control valve V4 when the travel shuttle valve 178 and the arm operation lever 146 are swung to one side or the other side ( The high pressure side) is sent to the rod side of the auto brake cylinder 177 An arm shuttle valve 179, and a transmission mechanism 180 for transmitting the movement of the piston rod 177a of the automatic brake cylinder 177 to the master cylinder 176.

The transmission mechanism 180 includes a first arm 182 and a second arm 183 whose base side are fixed to a rotatable first rotating part 181, and a third whose base side is fixed to a rotatable second rotating part 184. An arm 185, a fourth arm 186, an interlocking link 187 interlockingly connecting the distal end side of the second arm 183 and the distal end side of the third arm 185, and a piston rod 177a of the autobrake cylinder 177 in contact with the third link And a stopper 188 for restricting the movement in the protruding direction.
The front end side of the piston rod 177a of the auto brake cylinder 177 is connected to the front end side of the first arm 182, and the front end side of the push rod 189 of the master cylinder 176 is connected to the front end side of the fourth arm 186. When the piston rod 177a of 177 is retracted, the first arm 182 is moved to rotate the first and second arms 122, and the third arm 185 is moved by the interlocking link 187 to rotate the third and fourth arms 122. The fourth arm 186 pushes the push rod 189 of the master cylinder 176 to press the piston in the master cylinder 176, whereby the hydraulic oil in the master cylinder 176 is sent to the auto brake and the auto brake Is actuated to brake the wheels 4 and 5.

In this autobrake system 150, when the arm operating lever 146 is operated, the pilot hydraulic oil from the arm / turning remote control valve 147 is supplied to the rod side of the autobrake cylinder 177 via the arm shuttle valve 179. Is done.
At this time, if the travel pedal 110 is depressed, the pilot hydraulic oil from the travel remote control valve 114 is supplied to the bottom side of the auto brake cylinder 177 via the travel shuttle valve 178, so that the pressure receiving area is large. By boosting the bottom side, the piston rod 177a of the autobrake cylinder 177 does not move in the retracting direction.

Excess pilot hydraulic oil is drained through a relief valve.
Further, when the traveling pedal 110 is not depressed when the arm operating lever 146 is operated, the pressure on the rod side of the auto brake cylinder 177 is increased, so that the piston rod 177a of the auto brake cylinder 177 is retracted and moved automatically. The brake is activated.
When the operation of the arm operating lever 146 is released, the pilot hydraulic oil on the rod side of the auto brake cylinder 177 flows to the drain circuit via the arm shuttle valve 179 and the auto brake is released.

  An autobrake system 150 shown in FIG. 15A includes a travel switching valve 191 interposed in a hydraulic fluid flow path from the main pump 58 to the bottom side of the autobrake cylinder 177, and an upstream of the travel switch valve 191. One of the pilot hydraulic oil sent from the arm / swing remote control valve 147 to the arm control valve V4 when the pilot check valve 192 provided on the side and the arm operation lever 146 are swung to one side or the other side. An arm shuttle valve 179 for sending the part to the pilot check valve 192, and a transmission mechanism 180 for transmitting the movement of the piston rod 177a of the auto brake cylinder 177 to the master cylinder 176.

The travel switching valve 191 is configured by a switching valve similar to the first switching valve 153 described above, the pilot check valve 192 is configured by a pilot check valve similar to the second switching valve 154 described above, and the transmission mechanism 180 is In the transmission mechanism 180 described above, the stopper 188 is not provided, and the fourth arm 186 has a different direction, and other configurations are the same as those of the transmission mechanism 180 described above.
In this automatic brake system 150, when the travel pedal 110 is not depressed, the travel switching valve 191 is switched to the cutoff position 191b, and when the arm operation lever 146 is not operated, the pilot check valve 192 is switched. Is closed, and when the operating lever 146 for arm operation is operated and the travel pedal 110 is not depressed, the pilot hydraulic oil from the arm / swivel remote control valve 147 passes through the arm shuttle valve 179 and becomes a pilot check valve. Then, the pilot check valve 192 is opened and the travel switching valve 191 is excited and switched to the communication position 191a. The hydraulic oil from the main pump 58 is supplied to the bottom side of the auto brake cylinder 177.

Then, the piston rod 177a of the autobrake cylinder 177 protrudes, the first arm 182 is pushed and the first and second arms 122 rotate, and the third arm 185 is pushed by the interlocking link 187 and the third and third arms 182 and 122 rotate. The fourth arm 122 rotates, and the fourth arm 186 pushes the push rod 189 of the master cylinder 176 to press the piston in the master cylinder 176, so that the hydraulic oil in the master cylinder 176 is sent to the auto brake. As a result, the autobrake is activated and the wheels 4 and 5 are braked.
In the autobrake system 150 shown in FIG. 15B, the travel switching valve 191 in the autobrake system 150 shown in FIG. 15A is configured by a pilot operation switching valve, and the travel pedal 110 is depressed. Is different in that it includes a travel shuttle valve 178 for sending a part of the pilot operating pressure from the travel remote control valve to the travel switching valve 191 when the vehicle is stepped or rearwardly depressed. It is configured in substantially the same manner as the autobrake system 150 shown in b).

It is a side view of a wheel loader. It is a side view of a traveling body and a turning machine body. It is a top view of a traveling body. It is a top sectional view of a traveling system main power transmission mechanism. It is a plane sectional view of a main brake and a parking brake. It is a side view of a working device. It is a hydraulic circuit diagram by the side of the turning body of the hydraulic circuit of a wheel loader. It is a hydraulic circuit figure by the side of a running body of a hydraulic circuit of a wheel loader. It is a system schematic block diagram which shows an example of an autobrake system. It is a system schematic block diagram which shows operation | movement of the autobrake system shown in FIG. It is a system schematic block diagram which shows the other example of an autobrake system. It is a system schematic block diagram which shows the other example of an autobrake system. It is a system schematic block diagram which shows the other example of an autobrake system. It is a system schematic block diagram which shows the other example of an autobrake system. It is a system schematic block diagram which shows the other example of an autobrake system.

Explanation of symbols

4 Front wheel 5 Rear wheel 6 Traveling machine body 62 Brake 93 Turning machine body 95 Working device 109 Brake pedal (traveling system brake operation means)
110 Traveling pedal (traveling operation means)
120 Boom 122 Arm 123 Bucket (Working tool)
137 Arm cylinder 146 Operation lever (arm operation means)
150 Autobrake System 153 First Switching Valve 154 Second Switching Valve 155 Shuttle Valve 163 Pipe Lines 164, 165 Pressure Relief Circuit V4 Arm Control Valve

Claims (9)

A machine body (6, 93) supported movably by wheels (4, 5) and a work device (95) supported by the machine body (6, 93) are provided. A boom (120) whose side is swingably supported by the fuselage (6, 93), an arm (122) pivotally connected to the tip side of the boom (120), and the arm (122) A wheel loader configured to include a work tool (123) swingably provided on the tip side of
When the traveling operation means (110) for traveling the body (6, 93) is not operated and the arm (122) is swung, the wheel ( 4. A method of automatically braking a wheel loader, characterized by braking 4,5). A machine body (6, 93) supported movably by wheels (4, 5) and a work device (95) supported by the machine body (6, 93) are provided. A boom (120) whose side is swingably supported by the fuselage (6, 93), an arm (122) pivotally connected to the tip side of the boom (120), and the arm (122) A wheel loader configured to include a work tool (123) swingably provided on the tip side of
When the traveling operation means (110) for traveling the body (6, 93) is not operated and when the arm (122) is swung, the brake ( 62) A wheel loader comprising an autobrake system (150) for actuating 62) to brake the wheels (4, 5).   A hydraulically operated brake (62) for braking the wheels (4, 5) is provided, and the arm (122) is swung when the travel operation means (110) is not operated and the arm (122) is swung. Part of the hydraulic oil supplied to the arm cylinder (137) to be moved is sent to the brake (62), and the brake (62) is actuated by the hydraulic oil to brake the wheels (4, 5). The wheel loader according to claim 2, wherein the wheel loader is configured as described above.   Flow of hydraulic oil from the arm cylinder (137) side to the brake (62) side in the hydraulic oil flow path from the arm cylinder (137) side to the brake (62) when the traveling operation means (110) is not operated. When the travel operation means (110) is operated, a first switching valve (153) for interrupting the flow of hydraulic oil from the arm cylinder (137) side to the brake (62) side is provided. When the arm (122) swings between the first switching valve (153) and the arm cylinder (137) side, hydraulic fluid flows from the arm cylinder (137) side to the first switching valve (153). And a second switching valve (154) for interrupting the flow of hydraulic oil from the arm cylinder (137) side to the first switching valve (153) when the arm (122) is not rocked. That is characterized by Wheel loader according to claim 3.   When the travel operation means (110) is operated and the arm (122) is not rocked, the pressure in the pipe line (163) between the first switching valve (153) and the second switching valve (154) is released. The wheel loader according to claim 4, further comprising a pressure relief circuit (164, 165).   Flow of hydraulic oil from the arm cylinder (137) side to the brake (62) side in the hydraulic oil flow path from the arm cylinder (137) side to the brake (62) when the traveling operation means (110) is not operated. When the travel operation means (110) is operated, a first switching valve (153) for interrupting the flow of hydraulic oil from the arm cylinder (137) side to the brake (62) side is provided. When the arm (122) swings between the first switching valve (153) and the brake (62), hydraulic fluid is allowed to flow from the first switching valve (153) to the brake (62). Further, when the arm (122) is not rocked, a second switching valve (154) for interrupting the flow of hydraulic oil from the first switching valve (153) to the brake (62) side is provided. The wheel row according to claim 3 . The wheel loader according to claim 4, 5 or 6,
The second switching valve (154) is an arm operating means for operating the arm (122) by a hydraulic signal sent from a pilot valve for operating the arm control valve (V4) for controlling the arm cylinder (137). A wheel loader that is switched by an electric signal transmitted during the operation of (146). The wheel loader according to claim 4, 5 or 6,
The second switching valve (154) is constituted by an electromagnetic switching valve, and when the arm operating means (146) is operated so as to swing the arm (122) in one direction, the arm can be switched so as to allow the hydraulic fluid to flow. A second switching valve (154) for direction operation and an arm other direction operation that is switched to allow the flow of hydraulic oil when the arm operation means (146) is operated so as to swing the arm (122) in the other direction. A wheel loader characterized in that a second switching valve (154) is provided.   The brake (62) can also be actuated by hydraulic oil sent by the operation of the travel system brake operation means (109) that is manually operated during travel, and is sent by the travel system brake operation means (109). One of the hydraulic oil and the hydraulic oil sent from the arm cylinder (137) side when the traveling operation means (110) is not operated and the arm (122) is swung is supplied to the shuttle valve. The wheel loader according to any one of claims 3 to 7, wherein the wheel loader can be selectively supplied to the brake (62) via (155).

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