JP4484610B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle referred to as a TLB in which a front loader is attached to a front portion of a tractor and a backhoe is attached to a rear portion.

2. Description of the Related Art Conventionally, there is a work vehicle called TLB in which a front loader is attached to a front portion of a tractor and a backhoe is attached to a rear portion (see Patent Document 1).
A three-point link can be attached to the rear part of the vehicle body to the tractor, and a rear work machine can be attached to the rear part via the three-point link, and the rear work machine can be attached to the rear part of the vehicle body. A hydraulic lifting device that moves up and down is provided.

The hydraulic circuit of the TLB has a structure shown in FIG.
In FIG. 11, the hydraulic lifting device 116 includes a hydraulic cylinder 117 and a position control valve 118 that controls the hydraulic cylinder 117 to perform position control (position control) of the rear working machine.
The tractor operates on the main loader P1 that supplies hydraulic oil to the front loader, the backhoe and the hydraulic cylinder 117, the swing pump P2 that supplies hydraulic oil to the swing cylinder that swings the swing bracket of the backhoe, and the power steering device 119. A power steering pump P3 for supplying oil is provided, and these hydraulic pumps P1, P2, P3 are attached to the right side surface of the clutch housing constituting the vehicle body of the tractor.

In addition, the TLB is configured to flow the hydraulic oil from the main pump P1 to the load control valve 120 that controls the front loader and then to the backhoe control valve 121 or the position control valve 118 that controls the backhoe. Yes.
In addition, the TLB passes through the loader control valve 120 when the front loader is not attached and when the hydraulic oil from the main pump P1 flows to the position control valve 118 side (open state) when the front loader is not attached. A first switching valve 122 is provided for switching to a state where the backhoe control valve 121 or the position control valve 120 is allowed to flow (blocking state) later, and the hydraulic oil that has passed through the loader control valve 120 when the backhoe is not attached is supplied to the position control valve 118. A second switching valve 123 that switches between a state of flowing to the side (open state) and a state of shutting off the flow of hydraulic oil to the position control valve 118 side after passing through the loader control valve 120 when the backhoe is mounted (blocking state). In addition, when the backhoe is mounted, the hydraulic oil from the swing pump P2 is supplied to the backhoe control valve 121 (blocked state), and when the backhoe is not mounted, the hydraulic oil from the swing pump P2 is drained to the oil tank T ( A third switching valve 124 for switching to the open state).

In this TLB, at the time of shipment or the like, an inspection for confirming the operation of the hydraulic lifting device is performed with the front loader and the backhoe removed from the tractor. At this time, the hydraulic oil flows to the position control valve 118. The first switching valve 122, the second switching valve 123, and the third switching valve 124 are all opened.
The first switching valve 122 is mounted and fixed near the main pump P1 on the right side surface of the clutch housing, the second switching valve 123 is mounted and fixed on the front side of the housing 125 of the hydraulic cylinder 117, and the third switching valve 124 is a tractor. It is fixedly attached to the right side of the mission case that constitutes the vehicle body.
JP 2001-49700 A

In the prior art, the first switching valve 122, the second switching valve 123, and the third switching valve 124 are formed separately from the hydraulic cylinder 117, so that the cost is high.
In view of the above problems, an object of the present invention is to reduce costs by simplifying the structure of a hydraulic system.

The technical means of the present invention for solving this technical problem is that the front loader can be attached to the front part of the vehicle body, the backhoe can be attached to the rear part, and the hydraulic equipment for raising and lowering the rear working machine attached to the rear part of the vehicle body. A working vehicle equipped with a cylinder and configured to flow hydraulic oil from a hydraulic pump to a load control valve for controlling a front loader and then to a backhoe control valve for controlling a backhoe or a cylinder control valve for controlling a hydraulic cylinder. And
An inlet port is formed in the housing of the hydraulic cylinder to connect a branch pipe branched from a pipe from the loader control valve to the backhoe control valve, and a main supply path for flowing hydraulic oil entering from the inlet port to the cylinder control valve is formed. A main switching valve that is formed in the housing and that switches between a state in which the supply path is shut off and a state in which the supply path is opened is provided in the main supply path.

Further, the housing of the prior SL hydraulic cylinders, formed a pump port conduit supplying a hydraulic fluid from said hydraulic pump is connected, an outlet port conduit for supplying hydraulic fluid to the loader control valve is connected A sub- supply path is formed in the housing for communicating hydraulic fluid to the cylinder control valve by communicating with a communication path that connects the pump port and the outlet port. The sub- supply path is opened and closed. It is preferable to interpose a sub- switching valve that switches to a state to perform.

Further , the sub supply path and the main supply path are preferably connected to the cylinder control valve through a common oil path in communication with the sub switching valve and the main switching valve on the downstream side .
Also, the hydraulic cylinder housing is provided with an oil passage formation hole formed linearly from the outer surface thereof, and an oil output oil passage formed so as to intersect the oil passage formation hole from the outer surface of the housing, the first mounting hole, the second mounting hole, provided in this order toward the far side of the oil input oil passage from the open end of the oil passage forming hole, the open end of the oil passage forming hole and the pump ports, the open end of the oil output oil passage Is used as the outlet port, the sub switching valve made of a rotary spool type switching valve is inserted into the first mounting hole, the main switching valve made of the rotary spool type switching valve is inserted into the second mounting hole, and the oil input oil passage It is preferable that the open end is the inlet port.

Also, specifically, the sub-switching valve, a front loader and a state in which the hydraulic fluid from the hydraulic pump to a non-connecting state flow into the cylinder control valve side, the loader control valve hydraulic oil from the hydraulic pump to the front loader is installed The main switching valve is configured to flow the hydraulic oil after passing through the loader control valve to the cylinder control valve side when the backhoe is not installed and to the backhoe control valve or the cylinder control valve. It switches to the state which interrupts | blocks the flow to the cylinder control valve side of the hydraulic oil after passing a loader control valve at the time of installation .

The front SL in the hydraulic cylinder housing, the other pump port conduit supplying a hydraulic fluid from the other hydraulic pump to the housing side is connected, the hydraulic fluid from said other hydraulic pump to the backhoe control valves the form and another outlet port conduit is connected for supplying back to the oil tank hydraulic oil in communication with the other communication passage which communicates with these other pump port and the other outlet port drain An oil passage may be formed in the housing, and a drain switching valve for switching between a state in which the drain oil passage is shut off and a state in which the drain oil passage is opened may be interposed in the drain oil passage .

In addition, the hydraulic cylinder housing is provided with another oil passage forming hole formed in a straight line, and another oil input oil passage formed so as to intersect the other oil passage forming hole from the outer surface of the housing. formed, the oil input oil passage open end of the said other pump port, a tank fluid passage other end communicates with the oil tank at one end communicating with the other oil passage forming hole formed in the housing, the other the oil passage and said constitutes the drain fluid passage with the tank fluid passage, from its outer surface in the housing, the other oil passage forming hole between the tank oil passage of the oil passage forming hole and the other oil input oil passage A mounting hole formed so as to intersect the oil path between the other tank oil path and the other oil input oil path is provided, and the drain switching valve comprising a rotary spool type switching valve is inserted into the mounting hole. It is good to do.

  According to the present invention, the hydraulic system of a work vehicle can be switched with a front loader at the front of the vehicle body and a backhoe at the rear, and a hydraulic cylinder that lifts and lowers the rear work machine mounted at the rear of the vehicle body. By incorporating the switching valve for performing the above into the housing of the hydraulic cylinder, the structure of the hydraulic system can be simplified and the cost can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
2 and 3, reference numeral 1 denotes a work vehicle called a TLB. The work vehicle 1 is configured such that a front loader 3 can be attached to the front portion of the tractor 2 and a backhoe 4 can be attached to the rear portion.
The vehicle body 2A of the tractor 2 includes a front engine 5 and a transmission case 6 directly connected to the rear part of the engine 5 and is supported by a pair of left and right front and rear wheels 7 and 8 so as to be able to travel.

The transmission case 6 includes a clutch housing 9 connected to the rear part of the engine 5 via a flywheel housing or the like, and a transmission case 10 formed integrally with the rear part of the clutch housing 9 or connected separately. Yes.
A front axle frame 11 extending forward from the engine 5 is fixedly attached to the lower portions of the left and right side surfaces of the engine 5 with bolts. A battery, a radiator, a fuel tank, and the like are supported on the front axle frame 11. A battery, a radiator, a fuel tank, and the like are covered with a bonnet 12.

A fender 13 that covers the rear wheel 8 is provided on both the left and right sides of the rear part of the vehicle body 2A, and a driver's seat 14 is provided between the left and right fenders 13. And a rearward attitude for operating the backhoe 4 are supported on the vehicle body 2A so that the attitude can be freely changed.
A steering handle 15 is provided in front of the driver seat 14.

Work machine mounting frames 16 for mounting the front loader 3 and the backhoe 4 to the tractor 2 are disposed on the left and right sides of the vehicle body 2A. The left and right work machine mounting frames 16 are connected to each other, and the front portion is It is fixed to the lower part of the engine 5, and the rear part is fixed to the rear axle case 17 at the rear part of the transmission case 10.
A loader mounting member 18 is fixed to the front portion of each left and right work implement mounting frame 16 so as to protrude upward.

The front loader 3 has a side frame 19 that is detachably attached to the left and right loader attachment members 18, and a rear end side that is pivotally connected to an upper portion of the left and right side frames 19 so as to be rotatable about a horizontal axis. A boom 20 and a bucket 21 pivotally connected to a front end side of the left and right boom 20 so as to be rotatable about a left and right axis are provided.
The boom 20 is vertically swung by expansion and contraction of a boom cylinder 22 interposed between the side frame 19 and the boom 20, and the bucket 21 is expanded and contracted by the bucket cylinder 23 interposed between the boom 20 and the bucket 21. Squeeze dump operation.

  The backhoe 4 includes a base 24 that is detachably attached to the rear portions of the left and right work implement mounting frames 16, a swing bracket 25 that is supported on the rear portion of the base 24 so as to swing left and right about a vertical axis, and the swing. A boom 26 pivotally connected to the lower side of the bracket 25 so as to be rotatable about a left-right axis, and an arm pivotally connected to the tip side of the boom 26 so as to be rotatable about a left-right axis. 27, a bucket 28 pivotally connected to the distal end side of the arm 27, and outriggers (not shown) provided on both left and right sides of the base 24.

  The swing bracket 25 is swung left and right by expansion and contraction of a pair of left and right swing cylinders 30 interposed between the base and the swing bracket 25, and the boom 26 is interposed between the swing bracket 25 and the boom 26. The boom 27 is swung up and down by the expansion and contraction of the boom cylinder 31. The arm 27 is swung up and down by the expansion and contraction of the arm cylinder 32 interposed between the boom 26 and the arm 27. Squeezing and dumping are performed by the expansion and contraction of the bucket cylinder 33 interposed therebetween, and the outrigger is vertically swung by the outrigger cylinder interposed between the outrigger and the base 24.

  At the rear part of the vehicle body 2A, a three-point link 36 composed of an upper top link 34 and a pair of lower left and right lower links 35 arranged at the center in the left-right direction can be mounted. In a state in which the rear working machine is removed, a rear work machine such as a box scraper (leveling work machine), a rotary tiller, or the like can be mounted on the rear part of the vehicle body 2A via the three-point link 36 so as to be movable up and down.

  In addition, the work vehicle 1 includes a loader control valve 37 that controls the front loader 3 and a backhoe control valve 38 that controls the backhoe 4. The loader control valve 37 controls the boom cylinder 22 of the front loader 3. The backhoe control valve 38 includes a control valve that controls the swing cylinder 30 of the backhoe 4, a control valve that controls the boom cylinder 31, and a control that controls the arm cylinder 32. A valve, a control valve for controlling the bucket cylinder 33, a control valve for controlling the outrigger cylinder, and the like are provided.

At the rear of the vehicle body 2A, there is provided a hydraulic lifting device 39 that swings the lower link 35 of the three-point link 36 up and down to raise and lower the rear working machine. A cylinder 40 and a position control valve (cylinder control valve) 41 for controlling the hydraulic cylinder 40 are provided.
In the tractor 2, lubricating oil such as gears stored in the transmission case 10 is used as hydraulic oil for hydraulic equipment, and the transmission case 10 is used as an oil tank T for hydraulic oil.

As shown in FIGS. 1 and 4 to 10, the hydraulic cylinder 40 includes a housing 42, a piston 46 accommodated in a cylinder chamber 45 formed in the housing 42, and a piston pressed by the piston 46. It has a rod 47 and a pair of left and right lift arms 48 that are rotated by the piston rod 47.
The hydraulic cylinder 40 is constituted by a single-acting cylinder in which one end side of the cylinder chamber 45 is open, and the lower surface side of the housing 42 is fixedly attached to the rear upper surface of the transmission case 10.

  A rotation shaft 49 penetrating the housing 42 in the left-right direction is provided at the rear portion of the housing 42 so as to be rotatable about a left-right axial center. The base side (front part) of the lift arm 48 is attached, and the front end side (rear part) of each lift arm 48 is connected to the lower link 35 on the same side in the left-right direction via a lift rod.

One end side of the piston rod 47 is in contact with the piston 46, and the other end side is pivotally connected to the distal end side of a lever 50 attached to the rotating shaft 49 so as to be integrally rotatable.
Accordingly, when hydraulic oil is supplied to the back side of the piston 46 in the cylinder chamber 45 (the front side in FIG. 8), the piston 46 advances and the piston rod 47 is pressed, and the piston rod 47 passes the lever 50 through the lever 50. When the pivot shaft 49 is pivoted to swing the left and right lift arms 48 upward, and the lift arms 48 swing upward, the left and right lift rods are pulled up and the left and right lower links 35 swing upward. This raises the rear working machine attached to the three-point link 36.

Further, when the hydraulic circuit connected to the cylinder chamber 45 is communicated with the oil tank T, the rear working machine attached to the three-point link 36 is drained by the hydraulic oil on the back side of the piston 46 by its own weight. Descend.
The position control valve 41 is attached to the lower surface of the front portion of the housing 42 of the hydraulic cylinder 40 and includes a main switching valve 51 and a shutoff valve 52.

The main switching valve 51 is composed of a direct-acting spool type four-port three-position switching valve that can be switched between a lowered position 51a, a neutral position 51b, and a raised position 51c. It is composed of a switchable direct acting spool type 2-port 2-position switching valve.
In addition, the valve body of the position control valve 41 includes an oil input port 53 to which hydraulic oil is input, an oil output port 54 to which hydraulic oil is output, and first, second, and third ports that communicate with the oil tank T. Tank ports T1, T2, and T3 are formed.

In the position control valve 41, when the main switching valve 51 is switched to the neutral position 51b, the hydraulic oil entered from the oil input port 53 is drained from the first tank port T1 to the oil tank T. The shut-off valve 52 is in the shut-off position 52b and there is no pressure relief from the cylinder chamber 45, and the rear working machine does not descend.
When the main switching valve 51 is moved from the neutral position 51b to the raised position 51c, the shut-off valve 52 remains at the shut-off position 52b, and the pilot check valve 55 is closed by the pilot pressure from the hydraulic oil, so that the oil input port 53 Is prevented from draining from the first tank port T1 to the oil tank T, the hydraulic oil flows into the cylinder chamber 45, and the rear working machine rises.

Further, when the main switching valve 51 is moved from the neutral position 51b to the lowered position 51a, the hydraulic oil entered from the oil input port 53 is drained from the first tank port T1 to the oil tank T, while the shutoff valve 52 is opened. The hydraulic oil in the cylinder chamber 45 is drained from the second tank port T2 to the oil tank T, and the rear working machine is lowered.
The spool of the main switching valve 51 is provided with an operation portion 56 that protrudes forward from the valve body of the position control valve 41. The operation portion 56 is provided in the middle of the left and right spool operation lever 57 disposed on the front side thereof. A support shaft 58 to which a position lever is attached is interlocked and connected to one end side (right end portion) of the spool operating lever 57 via an arm 59, and the spool of the main switching valve 51 is connected to the spool of the position lever. By moving the spool operating lever 57 by the swinging operation, the spool operating lever 57 is pushed and pulled by the spool operating lever 57 to switch from the neutral position 51b to the raised position 51c or the lowered position 51a.

A feedback lever shaft 61 to which a feedback lever 60 is attached is interlocked and connected to the other end side (left end portion) of the spool operating lever 57 via an arm 62, and the feedback lever 60 is connected via a feedback link 63. The lift arm 48 is linked and connected.
Then, the spool of the main switching valve 51 is pulled or pushed via the spool operating lever 57 or the like by the swinging operation of the position lever, so that the main switching valve 51 is switched to the raised position 51c or the lowered position 51a, and the lift arm 48 is moved. When rotating up and down, the spool of the main switching valve 51 is pushed or pulled via the feedback link 63, the feedback lever 60, the feedback lever shaft 61, the arm 62, the spool operating lever 57, etc., and the main switching valve 51 is in the neutral position. The rear work machine moves up and down in proportion to the amount of movement of the position lever (the rear work machine can be raised and lowered to a position corresponding to the swing position of the position lever).

Therefore, the rear working machine can be stopped at a required position by stopping the lever position of the appropriate height of the rear working machine with a lever stopper or the like.
As a cylinder control valve for controlling the hydraulic cylinder 40, the hydraulic cylinder 40 is actuated by the traction load applied to the spring, and the rear working machine is automatically raised when the traction resistance is increased, and is lowered when the traction load is reduced. A draft control valve for controlling the hydraulic cylinder 40 may be employed.

  The tractor 2 includes a main pump P1 that supplies hydraulic oil to the loader control valve 37, the backhoe control valve 38, and the position control valve 41, and a swing pump that supplies hydraulic oil to the swing cylinder control valve of the backhoe control valve 38. A hydraulic pump such as a power steering pump P3 that supplies hydraulic oil to P2 and the power steering device PS is provided. These hydraulic pumps P1, P2, and P3 are provided on the left outer surface of the clutch housing 42, for example. Driven by rotational power.

  The housing 42 of the hydraulic cylinder 40 is connected to a pump port (referred to as a first pump port) 66 to which a conduit (this is referred to as a first conduit) 65 through which hydraulic oil from the main pump P1 flows, and a hydraulic pressure. An outlet port (this is referred to as a first outlet port) 68 to which a pipeline (this is referred to as a second outlet) 67 for flowing hydraulic oil from the cylinder 40 to the loader control valve 37 is connected, and a backhoe control valve from the loader control valve 37 to the loader control valve 37. 38, an inlet port 71 to which a branch line 70 branched from a pipe line (this pipe is referred to as a third pipe line) 69 is connected, and a pipe line (this is a fourth pipe) through which hydraulic oil from the swing pump P2 flows. A pump port (this is referred to as a second pump port) 73 to which the 72) is connected, and the backhoe control valve from the hydraulic cylinder 40 8 conduit supplying hydraulic fluid to the swing cylinder control valve of the outlet port (called second outlet port) 75 for connecting (a fifth of conduit which) 74 are formed.

A pipeline means a tube, pipe, hose or system that serves to guide hydraulic oil.
A first oil passage forming hole 76 is formed in the upper right portion of the front portion of the housing 42 so as to be linearly formed from the front side to the rear side of the housing 42 and open at the front end side and closed at the rear end side. Yes.
The opening end side (front end side) of the first oil passage forming hole 76 is formed with a slightly larger diameter than the portion extending from the midway portion to the rear end, and this large diameter portion is defined as a first oil input oil passage 76a. ing.

  Further, the upper portion of the right side of the front portion of the housing 42 is formed so as to cross (orthogonally) the first oil passage forming hole 76 from the right side surface to the left and to the first oil passage forming hole 76. An oil output oil passage (this is referred to as a first oil output oil passage) 77, a first attachment hole 78, a second attachment hole 79, and an oil input oil passage (this is referred to as a second oil input oil passage) 80 communicated. The first oil passage forming hole 76 is provided in order from the opening end side (front end side) to the back side (rear side).

The opening end of the first oil passage forming hole 76 is the first pump port 66, the opening end of the first oil output oil passage 77 is the first outlet port 68, and the first mounting hole 78 and the second mounting hole. Switching valves 81 and 82 are respectively mounted on 79 (the switching valve mounted in the first mounting hole 78 is called a first switching valve 81 (sub switching valve), and the switching valve mounted in the second mounting hole 79 is called a switching valve. the second switching valve 82 that (main switching valve)), the open end of the second oil input oil passage 80 is between the inlet port 71.

The first oil input oil passage 76 a and the first oil output oil passage 77 constitute a communication passage 83 that connects the first pump port 66 and the first outlet port 68.
The first pump port 66, the first outlet port 68, and the inlet port 71 can be closed by plugs.
Each of the first switching valve 81 and the second switching valve 82 is composed of a rotary spool type switching valve, and is inserted into the first and second mounting holes 78 and 79 so as to be rotatable about the left and right axis, The hydraulic fluid circulation holes 84 and 85 formed in the direction orthogonal to the rotation axis in the left-right direction are formed in a penetrating manner, and the first switching valve 81 and the second switching valve 82 are around the rotation axis. , The hydraulic oil circulation holes 84 and 85 communicate with the first oil passage formation hole 76 (a state in which the first oil passage formation hole 76 is opened), and the hydraulic oil circulation holes 84 and 85 The first oil passage forming hole 76 can be switched to a shut-off state (a state in which the first oil passage forming hole 76 is shut off), and the hydraulic oil circulation hole 84 of the first switching valve 81 is a first oil passage. The second switching valve is formed to have a smaller diameter than the part extending from the middle part to the rear end of the formation hole 76. 2 of the hydraulic oil flow hole 85 is formed in the same diameter as the portion over the rear from the intermediate portion of the first oil passage forming hole 76.

  The first switching valve 81 is prevented from being removed from the first mounting hole 78 by a retaining plate 86 screwed to the right side surface of the housing 42, and an operating portion provided on the outer end side of the first switching valve 81. 81a is immersed in a through hole 87 formed in the retaining plate 86. For example, the first switching valve 81 is rotated (switched) from the right side surface of the housing 42 by a flathead screwdriver or the like. .

  Further, the second switching valve 82 is prevented from coming off by a retaining member 88 screwed into the second mounting hole 79, and the operation portion 82 a of the second switching valve 82 projects rightward from the retaining member 88. An operating member such as an operating lever is connected to the operating portion 82a directly or via a connecting member, and the second switching valve 82 is turned by a swinging operation of the operating lever or the like (switching operation). Is done.

Further, one end side of the housing 42 is connected (communication) between the first mounting hole 78 and the second mounting hole 79 of the first oil passage forming hole 76, and the other end side is connected to the oil input port 53 of the position control valve 41. An oil input oil passage (this is referred to as a third oil input oil passage) 89 that is connected (communication) and inputs hydraulic oil to the position control valve 41 is formed. The oil path 76b between the first mounting hole 78 and the third oil input oil path 89 of the oil path forming hole 76 and the oil path 76c between the first oil output oil path 77 and the first mounting hole 78 are A supply path (this is referred to as a first supply path (sub-supply path) ) 90 is formed that communicates with the communication path 83 that connects the one pump port 66 and the first outlet port 68 to flow hydraulic oil to the position control valve 41. The first supply path 90 The first switching valve 81 to switch to the state to open state to cut off the supply path 90 is interposed.

  The third oil input oil passage 89 is formed in the vertical direction, and the upper end communicates between the first attachment hole 78 and the second attachment hole 79 of the first oil passage formation hole 76. And a second oil passage 89b that is formed in the vertical direction and whose lower end communicates with the oil input port 53 of the position control valve 41, and in the left-right direction so as to communicate with the first and second oil passages 89a and 89b. The third oil passage 89c is formed.

The housing 42 is formed with a main relief oil passage 91 having one end connected (communication) to the first oil output oil passage 77 and the other end communicated with the transmission case 10 (oil tank T). A main relief valve 92 is interposed in the relief oil passage 91.
Also, the third oil input oil passage 89, the oil passage 76d between the second mounting hole 79 of the first oil passage formation hole 76 and the third oil input oil passage 89, the second oil input oil passage 80 and the second oil passage 76 are provided. A supply path (this is referred to as a second supply path (main supply path)) for flowing hydraulic oil entering from the inlet port 71 to the position control valve 41 by the oil path 76e between the mounting hole 79 and the second oil input oil path 80. 93), and the second supply valve 93 is provided with a second switching valve 82 for switching the supply path 93 between a closed state and an open state.

The third oil input oil path 89 is a common oil path for the first supply path 90 and the second supply path 93, and the first supply path 90 and the second supply path 93 are the first The switch valve 81 and the second switch valve 82 communicate with each other downstream and are connected to the position control valve 41 by a common oil passage (third oil input oil passage 89).
In addition, a second oil passage forming hole 95 is formed in the upper left part of the front and rear midway portion of the housing 42 so as to be linearly formed from the rear to the front and the front and rear end portions are closed.

Further, the left upper part of the middle part of the front and rear of the housing 42 is formed so as to cross the second oil path forming hole 95 from the left side to the left and intersect (orthogonal) the second oil path forming hole. 95, a third mounting hole 96, a fourth oil input oil passage 97, and a fourth mounting hole 98 are formed in order from the front to the rear.
The open end of the fourth oil input oil passage 97 is the second pump port 73.

  Also, a switching valve 99 (referred to as a third switching valve) 99 comprising a rotary spool type switching valve is inserted into the third mounting hole 96 so as to be rotatable around the axial center in the left-right direction. The valve 99 is formed with a hydraulic fluid circulation hole 100 that is perpendicular to the rotational axis in the left-right direction. The hydraulic fluid circulation hole is formed by rotating the third switching valve 99 about the rotational axis. An open state in which 100 communicates with the second oil passage formation hole 95 (a state in which the second oil passage formation hole 95 is opened), and a shut-off state in which the hydraulic oil circulation hole 100 does not communicate with the second oil passage formation hole 95 (second It is possible to switch to the state in which the oil passage hole 95 is blocked.

  The third switching valve 99 is prevented from coming off by a retaining member 101 screwed into the third mounting hole 96, and the operation portion 99a of the third switching valve 99 protrudes rightward from the retaining member 101. An operating member such as an operating lever is connected to the operating portion 99a directly or via a connecting member, and the third switching valve 99 is rotated (switched) by a swinging operation of the operating lever or the like. The

  The housing 42 is linearly formed to the left from the right side surface of the housing 42, and communicates with the rear end side of the second oil passage formation hole 95 (this is the second oil output oil passage). 102 is formed, and the opening end of the second oil output oil passage 102 is the second outlet port 75. The second oil output oil passage 102, the fourth oil input oil passage 97, and the like. And a communication passage 103 that connects the second pump port 73 and the second outlet port 75 by an oil passage 95 a between the fourth oil input oil passage 97 and the second oil output oil passage 102 of the second oil passage formation hole 95. Is configured.

In addition, one end side (upper end side) of the housing 42 communicates with the front side of the third mounting hole 96 on the front end side of the second oil passage forming hole 95, and the other end side (lower end side) of the transmission case 10 ( A tank oil passage 104 communicating with the oil tank T) is formed (in the vertical direction).
A communication path that connects the second pump port 73 and the second outlet port 75 through the tank oil path 104 and the oil path 95b in front of the fourth oil input oil path 97 of the second oil path forming hole 95. A drain oil passage 105 that communicates with the hydraulic fluid 103 and returns the hydraulic oil to the tank is formed. The drain oil passage 105 is provided with a third switching valve 99 that switches between a state in which the drain oil passage 105 is shut off and a state in which the drain oil passage 105 is opened. Has been.

By making the third switching valve 99 shut off, the hydraulic oil from the swing pump P2 can be drained to the oil tank T when the backhoe 4 is removed.
A relief valve 106 is mounted in the fourth mounting hole 98, and a relief oil passage 107 formed downward from the fourth mounting hole 98 and communicating with the oil tank T is formed in the housing 42. Yes.

In the TLB 1 configured as described above, the operation check of the hydraulic lifting device 39 is inspected with the front loader 3 and the backhoe 4 removed at the time of shipment or the like. At this time, the first switching valve 81 is opened. The operation of the hydraulic lifting device 39 can be confirmed by setting the second switching valve 82 to the shut-off state and the third switching valve 99 to the open state.
Further, when the front loader 3 and the backhoe 4 are attached, as shown in FIG. 1, the first, second, and third switching valves 81, 82, and 99 are all cut off.

  When the main switching valve 51 of the position control valve 41 is in the neutral position 51b, the hydraulic oil is drained. Therefore, when the first switching valve 81 is in the open state, the loader control valve 37 and the backhoe control valve 38 are operated. If oil is not supplied and the second switching valve 82 is in the open state, hydraulic oil is not supplied to the backhoe control valve 38.

Further, even when the front loader 3 is operating, the backhoe control valve 38 is configured so that hydraulic oil flows.
When removing the backhoe 4 with the front loader 3 attached, the third switching valve 99 is opened to drain the hydraulic oil from the swing pump from the drain oil passage to the oil tank T, and the first switching valve. The second switching valve 82 is opened while keeping 81 in the shut-off state.

Further, with the backhoe 4 removed, the second switching valve 82 is opened while the first switching valve 81 is in the shut-off state, so that it can be raised and lowered via the three-point link at the rear portion of the vehicle body 2A. The rear work machine attached to the can be moved up and down.
According to the present invention, since the first switching valve 81, the second switching valve 82, and the third switching valve 99 are incorporated in the housing 42 of the hydraulic cylinder 40, the hydraulic circuit can be simplified and the cost can be reduced. .

  A first oil passage forming hole 76 is formed in the housing 42 of the hydraulic cylinder 40 linearly from the outer surface of the housing 42, and is formed so as to be orthogonal to the first oil passage forming hole 76 from the outer surface of the housing 42. An oil output oil passage 77, a first attachment hole 78, a second attachment hole 79, and a second oil input oil passage 80 are provided in order from the opening end of the first oil passage formation hole 76 to the back side to form a first oil passage. The opening end of the hole 76 is the first pump port 66, the opening end of the first oil output oil passage 77 is the first outlet port 68, the first switching valve 81 is inserted into the first mounting hole 78, and the second mounting hole By inserting the second switching valve 82 through 79 and using the opening end of the second oil input oil passage 80 as the inlet port 71, the hydraulic circuit can be simplified and the oil passage can be easily formed.

  Also, a fourth oil input oil passage is formed in the housing 42 of the hydraulic cylinder 40 so that the second oil passage formation hole 95 is formed in a straight line and intersects the second oil passage formation hole 95 from the outer surface of the housing 42. 97, and an opening end of the fourth oil input oil passage 97 serves as a second pump port 73, and a tank oil passage 104 having one end communicating with the second oil passage forming hole 95 and the other end communicating with the oil tank T A drain oil passage 103 is formed by the oil passage 95 a formed between the tank oil passage 104 and the fourth oil input oil passage 97 in the second oil passage formation hole 95 and the tank oil passage 104. A fourth mounting hole 98 formed so as to intersect the oil passage 95b between the tank oil passage 104 and the fourth oil input oil passage 97 of the second oil passage formation hole 95 is provided on the outer surface thereof. 4 When the third switching valve 99 is inserted into the mounting hole 98 , Hakare to simplify the hydraulic circuit, the oil passage formed is facilitated.

It is a hydraulic circuit diagram of the present invention. It is a side view of TLB. It is a top view of TLB in the state where a backhoe was removed. It is a top view of a hydraulic cylinder. It is a right view of a hydraulic cylinder. It is a left view of a hydraulic cylinder. It is a front view of a hydraulic cylinder. It is a side view of a hydraulic cylinder and a position control valve. FIG. 7 is a cross-sectional view taken along line B-B in FIG. 6. FIG. 6 is a cross-sectional view taken along line AA in FIG. 5. It is a conventional hydraulic circuit diagram.

2A body 3 front loader 4 backhoe 37 loader control valve 38 backhoe control valve 40 hydraulic cylinder 41 position control valve (cylinder control valve)
42 Housing 65 First Pipe 66 First Pump Port 67 Second Pipe 68 First Outlet Port 69 Third Pipe 70 Branch Pipe 71 Inlet Port 72 Fourth Pipe 73 Second Pump Port 74 Fifth Pipe 75 Second outlet port 76 First oil passage forming hole 77 First oil output oil passage 78 First mounting hole 79 Second mounting hole 80 Second oil input oil passage 81 First switching valve 82 Second switching valve 83 Communication passage 89 First 3 oil input oil passage 90 first supply passage 93 second supply passage 95 second oil passage formation hole 95b oil passage 96 third mounting hole 97 fourth oil input oil passage 99 third switching valve 103 communication passage 105 drain oil passage P1 Main pump P2 Swing pump T Oil tank (mission case)

Claims (7)

A front loader (3) can be attached to the front part of the vehicle body (2A), a backhoe (4) can be attached to the rear part, and a hydraulic cylinder (40) for raising and lowering a rear working machine attached to the rear part of the vehicle body (2A). A backhoe control valve (38) or a hydraulic cylinder (40) for controlling the backhoe (4) after flowing hydraulic oil from the hydraulic pump (P1) to a loader control valve (37) for controlling the front loader (3) A work vehicle configured to flow through a cylinder control valve (41) for controlling
An inlet port (71) for connecting a branch pipe (70) branched from a pipe (69) from the loader control valve (37) to the backhoe control valve (38) is provided in the housing (42) of the hydraulic cylinder (40). And forming a main supply passage (93) in the housing (42) for flowing hydraulic oil entering from the inlet port (71) to the cylinder control valve (41), and the main supply passage (93) A work vehicle comprising a main switching valve (82) for switching between a state where the supply passage (93) is shut off and a state where the supply passage (93) is opened. Actuating the housing (42) before SL hydraulic cylinder (40), wherein the pump port to the conduit supplying hydraulic oil from the hydraulic pump (P1) (65) is connected (66), the loader control valve (37) An outlet port (68) to which a pipe (67) for supplying oil is connected is formed and communicated with a communication passage (83) that communicates with the pump port (66) and the outlet port (68) to control the cylinder. A sub supply path (90) for flowing hydraulic oil to the valve (41) is formed in the housing (42), and the sub supply path (90) is cut off from the supply path (90) and opened. The work vehicle according to claim 1, further comprising a sub- switching valve (81) for switching. The sub supply path (90) and the main supply path (93) communicate with each other on the downstream side of the sub switching valve (81) and the main switching valve (82), and a cylinder is defined by a common oil path (89). The work vehicle according to claim 2, wherein the work vehicle is connected to a control valve (41). An oil passage forming hole (76) formed linearly from the outer surface is provided in the housing (42) of the hydraulic cylinder (40), and intersects the oil passage forming hole (76) from the outer surface of the housing (42). The oil output oil passage (77), the first attachment hole (78), the second attachment hole (79), and the oil input oil passage (80) formed as described above are connected to the back of the opening end of the oil passage formation hole (76). provided in this order toward the side, the open end of the oil passage forming hole (76) and the pump port (66), the oil output oil passage to the open end (77) and said outlet port (68), the first mounting hole (78) is inserted through the sub- switching valve (81) made of a rotary spool type switching valve, and the main switching valve (82) made up of the rotary spool type switching valve is inserted through the second mounting hole (79) to input oil. characterized in that the oil passage to the open end (80) and said inlet port (71) Working vehicle according to claim 2 or 3. The sub-switching valve (81) includes a state in which flow the hydraulic oil to the cylinder control valve (41) side from the front loader (3) is not mounted hydraulic pump (P1), the front loader (3) the hydraulic pump when worn The hydraulic oil from (P1) passes through the loader control valve (37) and then flows to the backhoe control valve (38) or the cylinder control valve (41). The main switching valve (82) (4) The state in which the hydraulic oil after passing through the loader control valve (37) flows to the cylinder control valve (41) when not installed, and the hydraulic oil after passing through the loader control valve (37) when installed in the backhoe (4) Monodea switched to the state to block the flow to the cylinder control valve (41) side Working vehicle according to any one of claims 2-4, characterized in that. The housing (42) before SL hydraulic cylinder (40), housing the hydraulic fluid from the other hydraulic pump (P2) (42) flow into the side pipe (72) other pump port which is connected (73) When the backhoe control other outlet port (75) of the conduit (74) is connected for supplying a hydraulic fluid from said other hydraulic pump (P2) to the valve (38) and is formed, these other A drain oil passage (105) that communicates with the other communication passage (103) that communicates the pump port (73) and the other outlet port (75) to return the hydraulic oil to the oil tank (T) is provided in the housing (42 ) to form, on the drain oil passage (105), wherein, characterized in that the drain oil passage selector valve (99) for drainage switched between a state to open state to cut off the (105) interposed In any one of items 1-5 Work vehicle of the mounting. The housing (42) of the hydraulic cylinder (40) is provided with another oil passage formation hole (95) formed in a straight line, and intersects the other oil passage formation hole (95) from the outer surface of the housing (42). The other oil input oil passage (97) formed to be formed is formed, the opening end of the oil input oil passage (97) is the other pump port (73), and one end side is the other oil passage formation hole. A tank oil passage (104) that communicates with (95) and communicates with the oil tank (T) at the other end is formed in the housing (42), and the tank oil passage (104) of the other oil passage formation hole (95) constitutes the oil passage (95b) and the drain fluid passage with the tank fluid passage (104) (105) between said other oil input oil passage (97), from its outer surface to the housing (42), the other tank oil passage of the oil passage forming holes (95) (104) and the other oil input oil passage An oil passage between the 97) (formed mounting hole so as to intersect 95b) and (96) is provided, said switching valve (99 for drainage made of rotating the spool type switching valve to the mounting hole (96)) The work vehicle according to claim 6, wherein the work vehicle is inserted.

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