Patent Application
20080066975
The above, and other objects, features and advantages of the present invention will become apparent from the detailed description thereof in conjunction with the accompanying drawings wherein.
A preferred embodiment of the present invention will now be described with reference to the accompanying drawings.
As shown in
In the present embodiment, the working vehicle 1A is an articulate type riding lawn mower, as shown in
Specifically, the vehicle frame 10 includes a first frame 11 arranged on the one side (a front side in the present embodiment) in the vehicle longitudinal direction; and a second frame 12 arranged on the other side (a rear side in the present embodiment) in the vehicle longitudinal direction, the second frame 12 being connected to the first frame 11 in a swingable manner about a pivot shaft 10 extending in a substantially vertical direction
In the present embodiment, the driving power source 30 and the hydraulic pump unit 100 are supported by the second frame 12, and the working machine 80 is supported by the first frame 11.
In the present embodiment, as shown in
As shown in
According to such a configuration, the vibration of the driving power source 30 is prevented from being propagated to the working machine 80 and the relative movement of the working machine 80 with respect to the driving power source 30 is allowed while preventing lowering in transmission efficiency from the driving power source 30 to the hydraulic pump unit 100 forming one part of the traveling system transmission mechanism and without the need for a complex configuration.
In other words, the working vehicle configured such that power is transmitted from a single driving power source to both the hydraulic pump unit and the working machine, has conventionally adopted a configuration (hereinafter referred to as first prior art configuration) of operatively connecting both the hydraulic pump unit and the working machine to the driving power source by way of shaft transmission mechanisms, or a configuration (hereinafter referred to as second prior art configuration) of operatively connecting both the hydraulic pump unit and the working machine to the driving power source by way of pulley-belt transmission mechanisms.
Specifically, in the first prior art configuration, the hydraulic pump unit includes a pump shaft that is shaft-connected to the driving power source through a shaft coupling, a hydraulic pump main body rotatably driven by the pump shaft, a pump case for accommodating the hydraulic pump main body, a PTO clutch mechanism accommodated in the pump case, a transmission gear mechanism accommodated in the pump case so as to operatively connect the pump shaft and a driving side of the PTO clutch mechanism, and a PTO shaft supported by the pump case while being operatively connected to a driven side of the PTO clutch mechanism.
The PTO shaft is connected to the working machine by way of a transmission shaft arranged with universal joints at both ends.
The first prior art configuration is advantageous in terms of transmission efficiency from the driving power source to the hydraulic pump main body and the working machine, but requires a complex configuration between the PTO shaft and the working machine to enable the working machine to be relatively movable with respect to the driving power source.
In particular, in the articulate type working vehicle as in the present embodiment in which the driving power source is supported by one of the vehicle frames and the working machine is supported by the other vehicle frame, the working machine relatively moves greatly with respect to the driving power source. Therefore, if the first prior art configuration is applied to the articulate type working vehicle, the shaft transmission mechanism between the PTO shaft and the working machine becomes complex and expensive.
Further, the first prior art configuration also poses a problem in that the vibration of the driving power source easily propagates to the working machine, thereby causing the working machine to vibrate.
The second prior art configuration allows the relative movement of the working machine with respect to the driving power source in a relatively easy manner since the working machine is operatively connected to the driving power source by way of the pulley-belt transmission mechanism, but the transmission efficiency of the traveling system transmission mechanism lowers since the hydraulic pump unit is also operatively connected to the driving power source by way of the pulley-belt transmission mechanism.
Furthermore, the second prior art configuration requires a large space for the power transmission structure since the pulley-belt transmission mechanism for transmitting power from the driving power source to the hydraulic pump unit and the pulley-belt transmission mechanism for transmitting power from the driving power source to the working machine are completely independent from each other, thereby enlarging the vehicle and lowering the degree of freedom of design.
In the present embodiment, on the other hand, the hydraulic pump unit 100 is operatively connected to the driving power source 30 by way of the shaft transmission mechanism 200 and the working machine 80 is operatively connected to the driving power source 30 by way of the endless belt transmission mechanism 250, as described above.
Therefore, the vibration of the driving power source 30 could be prevented from being propagated to the working machine 80 and the relative movement of the working machine 80 with respect to the driving power source 30 could be easily allowed while satisfactorily maintaining the transmission efficiency of the traveling system transmission mechanism and without the need for a complex configuration.
As shown in
In the present embodiment, a flywheel serving as the output member 35 is connected to an output shaft 31 of the driving power source 30.
Therefore, the coupling member 210 is configured to directly connect the flywheel and the pump shaft 110.
Specifically, as shown in
As shown in
In the configuration, the coupling member 210 is capable of being connected to one of the pump shaft 110 and the output shaft part 37 in a relatively non-rotatable manner, while being supported by the other of the pump shaft 110 and the output shaft part 37 in a relatively non-rotatable manner.
In the present embodiment, as shown in
The coupling member 210 is externally inserted around the pump shaft 110 in a relatively non-rotatable manner and in an axially movable manner by way of the spline, and is configured so as to be connected to an end face of the output shaft part 37 in a relatively non-rotatable manner by way of a fastening member.
In the present embodiment, the coupling member 210 is connected to the output shaft part 37 in a relatively non-rotatable manner by way of the fastening member 215, but alternatively, the coupling member 210 and the output shaft part 37 may be concave-convex-engaged so that the coupling member 210 is relatively non-rotatable with respect to the output shaft part 37. That is, the coupling member 210 may be provided with one of a concave portion and a convex portion that are capable of being engaged to each other, and the output shaft part 37 may be provided with the other of the concave and convex portions.
Furthermore, it is obviously possible that the coupling member 210 is internally inserted into one of the pump shaft 110 and the output shaft part 37. That is, one of the pump shaft 110 and the output shaft part 37 may be formed with an axis hole with a spline that opens to a end surface facing the other of the pump shaft 110 and the output shaft part 37, and the coupling member 210 that is internally inserted into the axis hole in a relatively non-rotatable manner may be connected to the other of the pump shaft 110 and the output shaft part 37 in a relatively non-rotatable manner.
The endless belt transmission mechanism 250 is configured so as to take out the rotational power from a power transmission path extending from the driving power source 30 to the pump shaft 110 of the hydraulic pump unit 100 via the shaft transmission mechanism 200, and to transmit the rotational power to the working machine 80.
Specifically, the endless belt transmission mechanism 250 includes a power takeoff pulley 260 arranged on the power transmission path and a first endless belt 265 wound around the power takeoff pulley 260, as shown in
In the present embodiment, the power takeoff pulley 260 is supported by the coupling member 210 in a relatively non-rotatable manner, as shown in
As described above, the driving power source 30 is supported by the second frame 12 and the working machine 80 is supported by the first frame 11 connected in a swingable manner about a pivot shaft 15 to the second frame 12, in the present embodiment.
Therefore, as shown in
In the present embodiment, the input-side intermediate pulley 270 and the output-side intermediate pulley 275 are supported by an intermediate shaft 273 (see
As shown in
Therefore, the endless belt transmission mechanism 250 further includes a direction-change pulley 290 for changing the direction of the first endless belt 265 between the power takeoff pulley 260 in which the rotation axis line is directed in the horizontal direction and the input-side intermediate pulley 270 in which the rotation axis line is directed in the vertical direction.
Furthermore, the endless belt transmission mechanism 250 includes a tension pulley 295 that acts on at least one of the first endless belt 265 and the second endless belt 285.
In the present embodiment, the tension pulley 295 acts on the second endless belt 285, as shown in
As described above, the hydraulic pump unit 100 is supported by the driving power source 30 by way of the attachment member 300 (see
As shown in
The base part 310 has a flange surface 311 (see
The supporting part 330 has a pump mounting surface 331 (see
The sidewall part 320 has a proximal end connected to the base part 310 and a distal end connected to the supporting part 330.
In the present embodiment, the sidewall part 320 is a peripheral wall for connecting the peripheral edge of the base part 310 and the peripheral edge of the supporting part 330, as shown in
Specifically, the sidewall part 320 includes a first peripheral wall 321 for surrounding at least a portion of the output member 35; and a second peripheral wall 325 extending in a direction close to the hydraulic pump unit 100 from the first peripheral wall 321, the second peripheral wall 325 having a diameter smaller than the first peripheral wall 321 so as to surround at least a portion of each of the power takeoff pulley 260 and the shaft transmission mechanism 200, as shown in
As shown in
As described above, in the present embodiment, the power takeoff pulley 260 is surrounded by the second peripheral wall 325. Therefore, the first opening 320a is provided in the second peripheral wall 325.
As shown in
By arranging the second opening 320b, the workability in attaching and detaching the first endless belt 265 to and from the power takeoff pulley 260 can be facilitated.
As described above, the power takeoff pulley 260 is surrounded by the second peripheral wall 325 in the present embodiment. Therefore, the second opening 320b is also provided in the second peripheral wall 325.
In the present embodiment, as shown in
That is, the driving power source 30 is normally supported in a vibration-absorbing manner by the vehicle frame 10 by way of a pair of right and left rear-side vibration-absorbing mounts and a pair of right and left front-side vibration-absorbing mounts to prevent the vibration of the driving power source 30 from propagating to the vehicle frame 10.
By arranging the mounting surfaces 328, it is possible to support the assembly of the driving power source 30 and the attachment member 300 on the vehicle frame 10 by positioning the pair of rear-side vibration-absorbing mounts 38R, for example, between the mounting stays 39 connected to the mounting surfaces 328 and the vehicle frame 10, as shown in
The present embodiment has the following configuration for allowing the attachment and detachment works of the first endless belt 265 with the hydraulic pump unit 100 supported by the driving power source 30 through the attachment member 300.
That is, as shown in
The coupling member 210 supported in a relatively non-rotatable manner by one (the pump shaft 110 in the present embodiment) of the output member 35 and the pump shaft 110 is movable in the axis direction with respect to the one of the output member 35 and the pump shaft 110, and takes a connecting position (see
According to the configuration, the first endless belt 265 can be passed through the gap 220 with the hydraulic pump unit 100 supported by the driving power source 30 by way of the attachment member 300 by disconnecting the coupling member 210 to the output member 35 and positioning the coupling member 210 at the opening position. Therefore, the attachment and detachment works of the first endless belt 265 to and from the power takeoff pulley 260 can be performed very easily.
In the present embodiment, as shown in
The right and left first wheel motor devices 50R, 50L have the same configuration with respect to each other, and are attached to the first frame 11 with one of the first wheel motor devices reversed by 180 degrees with respect to the other first wheel motor device.
Each wheel motor devices 50R, 50L includes a hydraulic motor unit 500 and a speed reduction gear unit 510.
As shown in
The speed reduction gear unit 510 includes a speed reduction gear mechanism 511 for speed-reducing the rotational output of the motor shaft 502, an output member 512 for outputting the rotational output speed-reduced by the speed reduction gear mechanism 511 to the corresponding driving wheel 21, and a gear case 513 for accommodating the speed reduction gear mechanism 511.
A second axle-driving device 60 includes a single hydraulic motor main body 551 directly or indirectly fluidly connected to the hydraulic pump main body 120, a motor shaft 552 for outputting the rotational power of the hydraulic motor main body 551, a speed reduction gear mechanism 553 for speed-reducing the rotational power of the motor shaft 552, a mechanical differential gear mechanism 554 for differentially transmitting the rotational power speed-reduced by the speed reduction gear mechanism 553 to the pair of right and left second driving wheels 22R, 22L, and an axle case 555 for accommodating the hydraulic motor main body 551, the motor shaft 552, the speed reduction gear mechanism 553 and the differential gear mechanism 554.
The second axle-driving device 60 is not limited to the above-described configuration.
For instance, the second axle-driving device may be configured to include a pair of right and left wheel motor devices for respectively driving the pair of right and left second driving wheels 22R, 22L, or the second axle-driving device may be configured to include a pair of hydraulic motor main bodies fluidly connected so as to form a closed circuit by way of a pair of hydraulic fluid lines, and a motor case for accommodating the pair of hydraulic motor main bodies.
In the present embodiment, as shown in
That is, as shown in
A forward-movement-low-pressure-side port 501R of the hydraulic motor main body 501 in the left-side wheel motor device 50L and a forward-movement-low-pressure-side port 501R of the hydraulic motor main body 501 in the right-side wheel motor device 50R are fluidly connected to a forward-movement-high-pressure-side port 551F of the hydraulic motor main body 551 in the second axle-driving device 60.
A forward-movement-low-pressure-side port 551R of the hydraulic motor main body 551 in the second axle-driving device 60 is fluidly connected to a forward-movement-low-pressure-side port 120R of the hydraulic pump main body 120.
A detailed configuration of the hydraulic pump unit 100 will now be described.
As shown in
The pump shaft 110 is supported by the pump case 130 in a rotatable manner about the axis line with the first end 111 forming the input end extending to the outer side.
In the present embodiment, the pump shaft 110 also has a second end 112 on the side opposite to the first end 111 extending to the outer side from the pump case 130, the second end 112 of the pump shaft 110 acting as an output end for outputting rotational power to a first auxiliary pump main body 610 and a second auxiliary pump main body 710, to be described later, as shown in
The hydraulic pump main body 120 includes a cylinder block 121 supported by the pump shaft 110 in a relatively non-rotatable manner in the pump space 100S and a plurality of pistons 122 supported by the cylinder block 121 in a relatively non-rotatable manner about the axis line and in a reciprocating manner in the axial direction, as shown in
In the present embodiment, the hydraulic pump unit 100 is a variable displacement type in which the suction/discharge amount of the hydraulic pump main body 120 is variable.
Therefore, the hydraulic pump unit 100 includes an output adjusting member 160 in addition to the above configuration.
In the present embodiment, the output adjusting member 160 includes a movable swash plate 161 that defines a reciprocating range of the piston 122 by directly or indirectly engaging with a free end of the piston 122, and a control shaft 162 supported by the pump case 130 in a rotatable manner about the axis line so as to extend in a direction orthogonal to the pump shaft 110, where the movable swash plate 161 can be slanted about a swing center by operating the control shaft 162 about the axis line.
The control shaft 162 is operatively connected to a travel speed-change operation member 6 capable of being manually operated by way of a control arm 163 (see
In the present embodiment, the movable swash plate 161 can be slanted in both forward and reverse directions with the neutral position in between.
In other words, the movable swash plate 161 slants in the forward movement direction when operating the travel speed-change operation member 6 (see
In the present embodiment, the output adjusting member 160 is a trunnion type in which the movable swash plate 161 and the control shaft 162 are integrated, as shown in
Furthermore, in the present embodiment, the hydraulic pump unit 100 includes a neutral position returning mechanism 165 for returning the movable swash plate 161 to the neutral position when the external operation force on the control shaft 162 is not applied, as shown in
The pump case 130 is formed with various fluid passages including a pair of hydraulic fluid passages 411 and 412 fluidly connected to the hydraulic pump main body 120.
In the present embodiment, the pump case 130 includes a pump case main body 140, and a port block 150 detachably connected to the pump case main body 140, the fluid passages being formed in the port block 150.
The pump case main body 140 has a hollow shape having an opening 140a that has a size allowing the hydraulic pump main body 120 to be inserted therethrough.
Specifically, the pump case main body 140 includes an end wall 141 positioned on a first side in the axial direction of the pump shaft 110 and a peripheral wall 142 extending to a second side in the axial direction of the pump shaft 110 from the peripheral edge of the end wall 141, and the opening 140a is formed at a free end side of the peripheral wall 142, as shown in
In the present embodiment, the end wall 141 is positioned on the input end side of the pump shaft 110 and the opening 140a is positioned on the output end side of the pump shaft 110, as shown in
As shown in
The port 140P is fluidly connected to an external tank 90, which will be described later, arranged in the working vehicle 1A by way of a conduit 145 (see
As shown in
The port block 150 is detachably connected to the pump case main body 140 so as to liquid-tightly close the opening 140a.
As described above, the port block 150 is formed with various fluid passages, in the present embodiment.
As shown in
The first and second hydraulic fluid passages 411, 412 have first ends opened to an outer surface to respectively form first and second hydraulic fluid ports 411(P), 412(P).
One of the first and second hydraulic fluid ports 411(P), 412(P) is the forward-movement-high-pressure-side port and the other is a backward-movement-high-pressure-side port (the forward-movement-low-pressure-side port).
As shown in
Specifically, as shown in
In the present embodiment, the charge port 420(P) is positioned on a surface facing the side opposite to the pump contacting surface 150a out of the surfaces of the port block 150, so as to easily receive hydraulic fluid from a first auxiliary pump main body 610 to be later described.
As shown in
By arranging the self-suction fluid passage 425, when one of the pair of first and second hydraulic fluid passages 411 and 412 becomes negative pressure, the fluid is automatically suctioned from the pump space 100S to the hydraulic fluid passage on the negative pressure side, thereby preventing a free wheel phenomenon that may occur, for example, at the time when the working vehicle is parked on a sloping road in a state where the engine is stopped with the HST being in the neutral state.
That is, when the working vehicle is parked with the above-described state, the rotational force is applied to the motor shaft operatively connected to the driving wheel, and the hydraulic motor main body supported by the motor shaft is prompted to perform a pumping action.
In this case, if the pair of hydraulic fluid lines fluidly connecting the hydraulic pump main body and the hydraulic motor main body are filled with hydraulic fluid, braking force acts on the hydraulic motor main body by the hydraulic fluid. At the same time, on the other hand, one of the pair of hydraulic fluid lines becomes to have a high pressure by the pump action of the hydraulic motor main body, and the hydraulic fluid may leak out from the one hydraulic fluid line having a high pressure.
When such a hydraulic fluid leakage occurs, fluid circulates from the other hydraulic fluid line having a low pressure to the one hydraulic fluid line having a high pressure, thereby promoting the hydraulic fluid leakage from the one high pressure side hydraulic fluid line. The hydraulic fluid in the pair of hydraulic fluid lines will be gone in the end, whereby the driving wheels start to freely rotate and the vehicle starts to go down the sloping road (free wheel phenomenon).
On the other hand, the self-suction fluid passage 425 could allow the fluid to be automatically supplied to the hydraulic fluid passage having a low pressure out of the first and second hydraulic fluid passages 411 and 412, thereby whereby effectively preventing the free wheel phenomenon.
As shown in
By arranging the bypass fluid passage 440 and the bypass valve 445, it is possible effectively prevent a pressure difference from being created between the pair of hydraulic fluid lines in forcibly towing the working vehicle 1A at the time of breakdown of the driving power source 30, the HST and the like.
In the present embodiment, the bypass valve 445 is a rotary valve configured so as to fluidly connect the bypass fluid passage 440 to a fluid reservoir (the pump space 100S in the present embodiment) when the bypass valve 445 has the bypass fluid passage 440 in the communicating state, as shown in
Specifically, as shown in
As shown in
The bypass valve 445 with the fluid passage 446 is capable of being rotated about the axis line based on an operation so as to communicate the bypass fluid passage 440 by way of the fluid passage 446 and fluidly connect the bypass fluid passage 440 to the drain fluid passage 449 when positioned at the communicating position of a first position about the axis line, and to shut off the bypass fluid passage 440 and fluidly disconnect the bypass fluid passage 440 to the drain fluid passage 449 when rotated about the axis line from the communicating position.
By providing a drain function in the bypass valve 445, it is possible to obtain an advantage of rapidly releasing air that has been entered into the pair of hydraulic fluid lines at the time, for example, when filling the pair of hydraulic fluid lines with hydraulic fluid from the pair of hydraulic fluid lines, in addition to the advantage of preventing the pressure difference from being created between the pair of hydraulic fluid lines in forcibly towing the working vehicle.
In the present embodiment, the following configuration is arranged in relation to the arrangement of the first and second hydraulic fluid passages 411, 412, the branched charge fluid passage 422, and the bypass fluid passage 420.
The first and second hydraulic fluid passages 411, 412 are arranged substantially in parallel with the pump shaft 110 in between, as shown in
The branched charge fluid passage 422 is formed so as to be orthogonal to the first and second hydraulic fluid passages 411, 412.
The bypass fluid passage 440 is formed so as to be orthogonal to the first and second hydraulic fluid passages 411, 412 on the side opposite to the branched charge fluid passage 420 with the pump shaft 110 as the reference.
According to the configuration, it is possible to efficiently arrange the fluid passages without enlarging the port block 150.
Furthermore, in the present embodiment, the branched charge fluid passage 422 is arranged on the same side as the hydraulic fluid ports 411(P), 412(P) with the pump shaft 110 as the reference, and the bypass fluid passage 440 is arranged on the side opposite to the hydraulic fluid ports 411(P), 412(P) with the pump shaft 110 as the reference, thereby effectively preventing an operation end of the bypass valve 445 from interfering with external conduits fluidly connected to the hydraulic fluid ports 411(P), 412(P), as shown in
In the present embodiment, the bypass valve 445 is inserted into an installation hole 450 formed in parallel to the first and second hydraulic fluid passages 411, 412 so that an opening end faces a direction opposite the hydraulic fluid ports 411(P), 412(P).
Preferably, the hydraulic pump unit 100 is provided with a neutral fluid passage for ensuring the neutral state of the HST formed by the hydraulic pump main body 120 and the hydraulic motor main bodies 501, 551 without the need for strict assembly precision.
The neutral fluid passage is, for example, a throttle or orifice 460 formed in at least one of the first and second check valves 431 and 432 so as to fluidly connect the branched charge fluid passage 422 and the corresponding hydraulic fluid passages 411 and 412.
In the present embodiment, the neutral fluid passage is formed in the second check valve 432 interposed between the second hydraulic fluid passage 412 that becomes high pressure in backward movement and the branched charge fluid passage 422, as shown in
By arranging the neutral fluid passage in the second check valve 432 that acts on the second hydraulic fluid passage 412 having a high pressure in backward movement, it is possible to effectively ensure the neutral width of the HST without lowering the transmission efficiency of the HST at forward movement of the vehicle that occupies a great amount of the traveling time, although the HST transmission efficiency at backward movement of the vehicle may lower.
Furthermore, in the present embodiment, a first auxiliary pump unit 600 including the first auxiliary pump main body 610 and a second auxiliary pump unit 700 including the second auxiliary pump main body 710 are connected to the hydraulic pump unit 100, as shown in
As shown in
As shown in
In the present embodiment, the first auxiliary pump main body 610 is a trochoid pump, as shown in
As shown in
As shown in
The first auxiliary pump discharge fluid passage 640 has a second end opened to the contacting surface with the port block 150 so as to be fluidly connected to the charge port 420(P), as shown in
Furthermore, as shown in
The relief valve 660 sets the charge pressure of the HST.
In the present embodiment, the hydraulic pressure setting fluid passage 650 has a second end fluidly connected to the suction side 611 of the first auxiliary pump main body 610, so that the relief fluid from the relief valve 660 is returned to the suction side 611 of the first auxiliary pump main body 610, as shown in
The second auxiliary pump unit 700 is connected to the outer surface on the side opposite to the port block 150 of the first auxiliary pump unit 600.
In other words, the first and second auxiliary pump units 600, 700 are connected in series to the hydraulic pump unit 100, in the present embodiment.
As shown in
As shown in
In the present embodiment, the second auxiliary pump main body 710 is a gear pump, as shown in
Specifically, as shown in
As shown in
In the present embodiment, the second auxiliary pump case 720 is further formed with a branched fluid passage 735.
As shown in
As shown in
The second auxiliary pump suction fluid passage 730 and the second auxiliary pump discharge fluid passage 740 are formed in the case main body 721.
The branched fluid passage 735 includes a first branched fluid passage 736 formed in the case main body 721 and a second branched fluid passage 737 formed in the plate member 722.
The first branched fluid passage 736 has a first end fluidly connected to the second auxiliary pump suction fluid passage 730 and a second end opened to a surface facing the plate member 722.
The second branched fluid passage 737 has a first end opened to the surface facing the case main body 721 so as to be fluidly connected to the first branched fluid passage 736 and a second end opened to the contacting surface with the first auxiliary pump case 610 so as to be fluidly connected to the second end of the first auxiliary pump suction fluid passage 630.
In the present embodiment, in a configuration in which the first and second auxiliary pump units 600, 700 are connected in series to the hydraulic pump unit 100, the suction port 700(in) for both the first auxiliary pump main body 610 and the second auxiliary pump main body 710 is formed in the second auxiliary pump case 720 of the second auxiliary pump unit 700 arranged spaced apart from the hydraulic pump unit 100 out of the auxiliary pump units 600, 700, thereby simplifying the conduit configuration for fluidly connecting the fluid source and the suction sides of the first and second auxiliary pump main bodies 610, 710, and effectively preventing the conduit fluidly connected to the suction port 700(in) from interfering with external conduits fluidly connected to the hydraulic fluid ports 411(P), 412(P) of the hydraulic pump unit 100.
In the present embodiment, the working vehicle 1A includes the external tank 90, as shown in
The discharge port 700(out) is fluidly connected to the hydraulic pressure steering mechanism 70 by way of an external conduit 760.
Another embodiment of the present invention will now be described with reference to the accompanying drawings.
The present embodiment is different from the first embodiment only in that the port block 150 in the hydraulic pump unit 100 is replaced with a port block 150B.
Therefore, only the different portion will be described below.
In the figure, the same reference characters denote the same members as in the first embodiment, and thus the description thereof will be omitted.
The port block 150B is different from the port block 150 in that the check valves 431, 432 are changed to a compound check valve 800, and in that the position of the bypass valve 445 is changed.
Specifically, the port block 150B is provided with first and second compound check valve 800a, 800b respectively interposed between the branched charge fluid passage 422, and the first and second hydraulic fluid passages 411, 412.
In the present embodiment, the neutral width of the HST is ensured by arranging the throttle 460 for constantly fluidly connecting the corresponding hydraulic fluid passages 411, 412 and the branched charge fluid passage 422, in one of the first and second checks valves 431 and 432.
The first and second compound check valves 800a, 800b, on the other hand, are configured to fluidly disconnect the corresponding hydraulic fluid passages 411, 412 to the branched charge fluid passage 422 when the hydraulic pressure of the corresponding hydraulic fluid passages 411, 412 exceeds a predetermined value, and to fluidly connect the corresponding hydraulic fluid passages 411, 412 to the branched charge fluid passage 422 by way of the throttle 460 when the hydraulic pressure of the corresponding hydraulic fluid passages 411, 412 comes below the predetermined value, thereby ensuring the neutral width of the HST while preventing the transmission efficiency of the HST from being deteriorated during traveling.
The first and second compound check valves 800a, 800b have the same configuration with respect to each other. Therefore, only the first compound check valve 800a will be described below.
The first compound check valve 800a includes a hollow valve case 810 arranged so as to liquid-tightly block between the branched charge fluid passage 422 and the corresponding first hydraulic fluid passage 411, the valve case 810 being provided with a charge-fluid-passage-side communication hole 815 for fluidly connecting the internal space to the branched charge fluid passage 422 and a hydraulic-fluid-passage-side communication hole 816 for fluidly connecting the internal space to the first hydraulic fluid passage 411; a hollow check valve main body 820 internally inserted in an axially slidable manner into the internal space of the valve case 810; a relief valve main body 830 internally inserted in an axially slidable manner into an internal space of the check valve main body 820; a check biasing member 840 acting on the check valve main body 820; and a relief biasing member 850 acting on the relief valve main body 830.
The valve case 810 includes a peripheral wall 811 extending in an axial direction, and an end wall 812 arranged at a distal end side of the peripheral wall 811, a proximal end side of the peripheral wall 811 being opened.
The valve case 810 having the configuration is internally inserted into an installation hole 801 formed in the port block 150B.
Specifically, the installation hole 801 is formed concentrically with the branched charge fluid passage 422 so as to have a distal end reaching the branched charge fluid passage 422 and a proximal end opening to the outer surface, as shown in
The valve case 810 is attached to the installation hole 801 such that the end wall 812 on the distal end side reaches the branched charge fluid passage 422 over the corresponding first hydraulic fluid passage 411 and the proximal end side is positioned on the side opposite to the branched charge fluid passage 422 with the first hydraulic fluid passage 411 in between.
The opening on the proximal end side of the installation hole 801 is closed by a cap 805.
The charge-fluid-passage-side communication hole 815 is formed in the end wall 812 of the valve case 810, and the hydraulic-fluid-passage-side communication hole 816 is formed at a portion positioned on the proximal end side (i.e., on the side opposite to the branched charge fluid passage 422 with the first hydraulic fluid passage 411 in between) from the first hydraulic fluid passage 411 out of the peripheral wall 811 of the valve case 810.
The check valve main body 820 is internally inserted into the internal space of the valve case 810 from the opening on the proximal end side of the valve case 810.
The check valve main body 820 includes a peripheral wall 821 slidably contacting the inner peripheral surface of the peripheral wall 811 of the valve case 810 in a liquid tight manner, and an end wall 822 arranged on a proximal end side of the peripheral wall 821, a distal end side of the peripheral wall 821 being opened.
The check biasing member 840 is arranged so as to bias the check valve main body 820 towards the distal end side.
In the present embodiment, the check biasing member 840 is interposed between the cap 805 and the end wall 822 of the check valve main body 820.
According to the configuration, when hydraulic fluid flows into the internal space of the valve case 810 from the branched charge fluid passage 422 through the charge-fluid-passage-side communication hole 815, the check valve main body 820 is pushed towards the proximal end side against the biasing force of the check biasing member 840 by the hydraulic fluid, whereby the internal space of the valve case 810 fluidly connects to the first hydraulic fluid passage 411 by way of the hydraulic-fluid-passage-side communication hole 816 so that the hydraulic fluid in the valve case 810 flows into the first hydraulic fluid passage 411.
Furthermore, the check valve main body 820 is formed, at the peripheral wall 822, with a check-valve-side communication hole 826 for fluidly connecting the hydraulic-fluid-passage-side communication hole 816 to the internal space of the check valve main body 820 according to the position in the axial direction of the check valve main body 820.
The relief valve main body 830 is internally inserted in a slidably moving manner in the axial direction into the check valve main body 820 from the opening on the distal end side of the check valve main body 820.
Specifically, the relief valve main body 830 has a hollow shape with a peripheral wall 831 extending in the axial direction, and an end wall 832 arranged on the distal end side of the peripheral wall 831.
The relief valve main body 830A is formed, at the end wall 832, with a throttle or orifice 460 for fluidly connecting the internal space of the relief valve main body 830 to the internal space of the valve case 810.
Furthermore, the relief valve main body 830 is provided, at the peripheral wall 831, with a relief-valve-side communication hole 836 for fluidly connecting the check-valve-side communication hole 826 to the internal space of the relief valve main body 830 according to the position in the axial direction of the relief valve main body 830.
The relief biasing member 850 biases the relief valve main body 830 towards the proximal end side.
In the present embodiment, the relief biasing member 850 is interposed between the end wall 812 of the valve case 810 and the end wall 832 of the relief valve main body 830.
The relief valve main body 830 and the relief biasing member 850 having such a configuration operate as follows.
The relief valve main body 830 is pushed towards the proximal end side by the biasing force of the relief biasing member 850 in the state where the hydraulic pressure of the corresponding first hydraulic fluid passage 411 is lower than a predetermined value. The relief-valve-side communication hole 836 is formed at such a position as to communicate with the check-valve-side communication hole 826 in this state.
In other words, when the hydraulic pressure of the corresponding first hydraulic fluid passage 411 is lower than the predetermined value, the first hydraulic fluid passage 411 fluidly connects to the branched charge fluid passage 422 by way of a flow path including the hydraulic-fluid-passage-side communication hole 816, the check-valve-side communication hole 826, the relief-valve-side communication hole 836, the internal space of the relief valve main body 830, the throttle 460, the internal space of the valve case 810 and the charge-fluid-passage-side communication hole 815 (see
Therefore, the neutral state of the HST can be obtained without the need for strict assembly precision.
When the hydraulic pressure of the corresponding first hydraulic fluid passage 411 exceeds the predetermined value, on the other hand, the relief valve main body 830 is pushed towards the distal end side against the biasing force of the relief biasing member 850 by the hydraulic pressure of the hydraulic fluid flowing into the internal space of the relief valve main body 830. In this state, the relief-valve-side communication hole 836 is fluidly disconnected to the check-valve-side communication hole 826 (see
Therefore, the hydraulic fluid in the first hydraulic fluid passage 411 is prevented from flowing out through the flow path when the vehicle travels and the first hydraulic fluid passage 411 has a high pressure, thereby effectively preventing the HST transmission efficiency from being deteriorated.
The installing position of the bypass valve 445 will now be described.
In the first embodiment, the bypass valve 445 is inserted into the installation hole 450 formed in parallel to the first and second hydraulic fluid passages 411, 412 so that the opening end faces a direction opposite to the hydraulic fluid ports 411(P), 412(P), and the operation end of the bypass valve 45 faces a direction opposite to the hydraulic fluid ports 411(P), 412(P) (see
In the present embodiment, on the other hand, the bypass valve 445 is arranged concentrically with the bypass fluid passage 440.
Specifically, the port block 150B is formed with an installation hole 450B in place of the installation hole 450, in the present embodiment.
The installation hole 450B is formed concentrically with the bypass fluid passage 440 so as to have a distal end reaching the bypass fluid passage 440 and a proximal end opening to the outer surface.
The bypass valve 445 is inserted into the installation hole 450B from the opening of the installation hole 450B.
According to such a configuration also, the operation end of the bypass valve 445 can be effectively prevented from interfering with the external conduits fluidly connecting to the hydraulic fluid ports 411(P), 412(P).
Still another embodiment of the present invention will now be described with reference to the accompanying drawings.
The present embodiment is different from the first embodiment only in the power transmission structure from the driving power source 30 to the pump shaft 110 and the endless belt transmission mechanism 250.
Therefore, only the different portion will be described below.
In the figure, the same reference numerals denote the same members as in the first embodiment, and thus the description thereof will be omitted.
In the first embodiment, the flywheel main body 36 and the output shaft part 37 in the output member 35 are in a rigid relationship with respect to each other.
In other words, the rigid flywheel main body 36 and the rigid output shaft part 37 are connected by way of a fastening member 37a in the output member 35 (see
In the first embodiment, the coupling member 210 is connected in a relatively non-rotatable manner and in a separable manner to the output shaft part 37 having a rigid relationship with respect to the flywheel main body 36.
In such a configuration, when a variation in angular speed is occurred in the output of the driving power source 30, such a variation is transmitted to the pump shaft 110, thereby causing pulsation in the hydraulic fluid suctioned/discharged by the hydraulic pump main body 120. Such a phenomenon is not preferable as it leads to a variation in vehicle speed of the working vehicle 1 and reduction of riding comfort.
In this regards, the working vehicle 1C according to the present embodiment includes an output member 35C in place of the output member 35.
As shown in
In other words, in the output member 35C, the elastic member 900 serving as a damper is interposed between the flywheel main body 36 and the output shaft part 37C that are separate to each other, so that even if a variation in angular speed is occurred in the output of the driving power source 30, the variation in angular speed is absorbed by the elastic member 900.
In the present embodiment, the elastic member 900 is connected to the output shaft part 37C by way of a fastening member 901 while being externally inserted around the output shaft part 37C, as shown in
Furthermore, the elastic member 900 is connected to the flywheel main body 36 by way of a fastening member 902.
In the illustrated embodiment, the elastic member 900 is connected to the flywheel main body 36 by way of a rigid plate 36C.
Similar to the first embodiment, the coupling member 210 is relatively non-rotatable and axially movable with respect to the pump shaft 110 while supporting the power takeoff pulley 260 in a relatively non-rotatable manner and in an axially movable manner, and takes a connecting position (see
According to such a configuration, in addition to the advantage that the attachment and detachment works of the first endless belt 265 can be performed with the hydraulic pump unit 100 supported by the driving power source 30 by way of the attachment member 300, it is possible to ensure an advantage in that the angular speed variation of the output of the driving power source 30 can be effectively prevented from propagating to the pump shaft 110.
Still another embodiment of the present invention will now be described with reference to the accompanying drawings.
The present embodiment is different from the first and third embodiments only in the power transmission structure from the driving power source 30 to the pump shaft 110 and the endless belt transmission mechanism 250.
Therefore, only the different portion will be described below.
In the figure, the same reference characters denote the same members as in the first and third embodiments, and thus the description thereof will be omitted.
In the third embodiment, the output shaft part 37C to which the coupling member 210 is detachably connected is connected to the flywheel main body 36 by way of the elastic member 900 serving as a damper, as described above.
Such a configuration is effective in that the angular speed variation of the output of the driving power source 30 can be prevented from propagating to the pump shaft 110, but if tension is applied to the first endless belt 265, the tension acts to decenter the coupling member 210 supporting the power takeoff pulley 260 with respect to the output member 35C (i.e. the tension acts to move the coupling member 210 radially with the axis line of the output member 35C as the reference), whereby unnecessary external force acts on the pump shaft 110.
In other words, in the third embodiment, the output shaft part 37C is connected to the flywheel main body 36 by way of the elastic member 900. In the power transmitting state, the coupling member 210 is connected to the output shaft part 37C. That is, in the power transmitting state, the coupling member 210 supporting the power takeoff pulley 260 is supported by the flywheel main body 36 by way of the elastic member 900.
Thus, when tension is applied to the first endless belt 265 wound around the power takeoff pulley 260 in this state, the tension acts on the coupling member 210 as a force moving the coupling member 210 radially from the axis line of the output member 35C.
Since the coupling member 210 is relatively non-rotatable with respect to the pump shaft 110 as described above, the force to move the coupling member 210 radially from the axis line of the output member 35C acts on the pump shaft 110, resulting in causing damage of the spline or damage of the pump shaft 110 and furthermore lowering the transmission efficiency.
In view of such an aspect, the working vehicle 1D according to the present embodiment adopts the following power transmission structure in regards to the power transmission from the driving power source 30 to the pump shaft 110 and the endless belt transmission mechanism 250.
The working vehicle ID includes an output member 35D in place of the output member 35C.
As shown in
The output shaft part 37D is configured so as to support the power takeoff pulley 260 in a relatively non-rotatable manner.
In the present embodiment, as shown in
Furthermore, the working vehicle ID includes a coupling member 210D in place of the coupling member 210.
Similarly to each embodiment described above, the gap 220 having a size that allows the first endless belt 265 to be passed therethrough is provided between the opposing ends of the pump shaft 110 and the output member 35D.
The coupling member 210D is relatively non-rotatable and axially movable with respect to the first end 111 of the pump shaft 110, and takes a connecting position (see
As shown in
Specifically, the elastic member 900 is connected to the coupling member 210D, and the coupling member 210D is configured to take the connecting position and the opening position along with the elastic member 900.
The elastic member 900 is configured so as to be connected to the output member 35D.
In the present embodiment, as shown in
The elastic member 900 can be connected to the output shaft part 37D by way of a fastening member 912 with the coupling member 210D positioned at the connecting position.
Specifically, the output shaft part 37D includes a main body part 370 which has an end on the upstream side in transmitting direction fixed to the flywheel main body 36 and to which the power takeoff pulley 260 is fixedly mounted; and a flange part 371 which is arranged on the downstream side in the transmitting direction of the main body part 370 and which extends radially outward from the main body part 370.
The elastic member 900 is detachably connected to the flange part 371 of the output shaft part 37D having the above configuration.
In the present embodiment of the above configuration, the following advantages can be obtained.
When the coupling member 210D is positioned at the opening position, an insertion space (the gap 220) for the first endless belt 265 is ensured between the assembly including the coupling member 210D and the elastic member 900, and the output member 35D. Therefore, the attachment and detachment works of the first endless belt 265 can be performed with the hydraulic pump unit 100 supported by the driving power source 30 by way of the attachment member 300.
Furthermore, the power transmission from the driving power source 30 to the pump shaft 110 is performed by way of the output member 35D, the elastic member 900 and the coupling member 210. Therefore, the angular speed variation of the output of the driving power source 30 can be effectively prevented from being propagated to the pump shaft 110 by the damper action of the elastic member 900.
Furthermore, the power takeoff pulley 260 is supported by the output shaft part 37D rigidly fixed with respect to the flywheel main body 36. Thus, the output shaft part 37D does not move radially from the axis line of the flywheel main body 36 even if the tension is applied on the first endless belt 265. Therefore, the tension on the first endless belt 265 is effectively prevented from acting on the pump shaft 110, thereby effectively preventing the pump shaft 110 to be damaged and also preventing the transmission efficiency to be deteriorated.
Still another embodiment of the present invention will now be described with reference to the accompanying drawings.
The present embodiment is different from the first and third embodiments only in the power transmission structure from the driving power source 30 to the pump shaft 110 and the endless belt transmission mechanism 250.
Therefore, only the different portion will be described below.
In the figure, the same reference characters denote the same members as in each embodiment described above, and thus the description thereof will be omitted.
The working vehicle 1E in the present embodiment includes an output member 35E and a coupling member 210E in place of the output members and the coupling members in the working vehicles 1A to 1D in the embodiments described above.
The output member 35E is a member for outputting rotational power of the driving power source 30, and is the flywheel main body 36 in the present embodiment, as shown in
The coupling member 210E is supported in a relatively non-rotatable manner and in an axially movable manner by the pump shaft 110, and is configured so as to be detachably connected with respect to the output member 35E.
Specifically, as shown in
The upstream-side member 211 supports the power takeoff pulley 260 in a relatively non-rotatable manner.
In the present embodiment, the upstream-side member 211 includes a main body part 211a that has an end on the upstream side in the transmitting direction directly or indirectly connected to the flywheel main body 36 and that supports the power takeoff pulley 260; and a flange part 211b that is arranged on the downstream side in the transmitting direction of the main body part 211a and that extends radially outward from the main body part 211a.
In the present embodiment, the upstream-side member 211 is connected to the flywheel main body 36 by way of a rigid plate 211c.
Specifically, the upstream-side member 211 further includes the rigid plate 211c fixedly attached to the end on the upstream side in the transmitting direction of the main body part 211a by way of a fastening member 211d, as shown in
The rigid plate 211c includes a central part 2110 contacting the main body part 211a, and an outward extending part 2111 extending radially outward from the central part 2110.
The outward extending part 2111 is preferably extended radially outward of the power takeoff pulley 260 fixedly attached to the main body part 2110.
The upstream-side member 211a is detachably connected to the flywheel main body 36 by a fastening member 2112 that is inserted into a slit or a hole formed in the outward extending part 2111.
The outward extending part 2111 is preferably arranged at a position other than the uppermost point of the power takeoff pulley 260. According to such a configuration, the workability of the attachment and detachment of the first endless belt 265 could be facilitated.
As shown in
In the present embodiment, the elastic member 900 is connected to the flange part 211b of the upstream-side member 211 by way of the fastening member 912.
The downstream-side member 212 is supported by the pump shaft 110 in a relatively non-rotatable manner and in an axially movable manner by way of a spline formed at the first end 111 of the pump shaft 110.
Specifically, the downstream-side member 212 is axially movable with respect to the pump shaft 110 so as to take connecting position (see
In the present embodiment, as shown in
Alternatively, the upstream-side member 211 may be formed with an axis hole into which the pump shaft 110 can be inserted in a relatively rotatable manner, where the gap 220 can be ensured by configuring such that the first end of the pump shaft 110 is inserted into the axis hole when the downstream-side member 212 is positioned at the opening position.
Similarly to the fourth embodiment, the present embodiment having the above-described configuration could simultaneously have the advantage that the attachment and detachment works of the first endless belt 265 can be performed with the hydraulic pump unit 100 supported by the driving power source 30 by way of the attachment member 300, the advantage that the angular speed variation of the output of the driving power source 30 can be effectively prevented from being propagated to the pump shaft 110, and the advantage that tension of the first endless belt 265 can be prevented from acting on the pump shaft 110.
This specification is by no means intended to restrict the present invention to the preferred embodiments and the modified embodiments set forth therein. Various modifications to the power transmission structure may be made by those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-252147 | Sep 2006 | JP | national |
| 2006-276208 | Oct 2006 | JP | national |
