JP2007182988A - Transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate complicated shift operation of a gear type transmission in a transmission device having a belt type automatic continuously variable transmission and the gear type transmission interposed between a prime mover and a wheel shaft. <P>SOLUTION: This gear type transmission 50 has a first gear train 50H of interposing a first clutch 73 engaging when a travel load is a predetermined value or more between an input part receiving motive power from the belt type automatic continuously variable transmission 40 and an output part outputting the motive power to the wheel shaft, and a second gear train 50L of interposing a second clutch 72 engaging when the first clutch is put in an unengaging state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a transmission device that is mainly used for a work vehicle such as a transport vehicle and is interposed between a prime mover and an axle, and includes a belt-type automatic continuously variable transmission and the belt-type automatic continuously variable transmission. It is related with a transmission provided with the gear type transmission driven by.

  Conventionally, a belt-type automatic continuously variable transmission (hereinafter referred to as “CVT”) as a main transmission, a gear-type transmission as a sub-transmission connected to the output side thereof, and the gear-type transmission are driven by the gear-type transmission. For example, Patent Document 1 discloses a vehicle structure to which such a transmission device is applied.

JP 2003-194097 A

  However, if the shifting operation of the sub-transmission is manual, the operation must be basically performed by stopping the vehicle, and it is cumbersome, and if it is operated incorrectly during traveling, the motor side or axle side at that time If the speed stage is unbalanced with the number of rotations, there is a possibility that the transmission efficiency may be reduced or the engine stalled due to insufficient torque.

  An object of the present invention is to provide a belt-type automatic continuously variable transmission that is interposed between a prime mover and an axle and is driven by the prime mover, and a gear-type transmission that is driven by the belt-type automatic continuously variable transmission. In the transmission device having the machine, the automatic transmission in the gear type transmission is made possible.

  In order to achieve this object, according to the present invention, a belt-type automatic continuously variable transmission driven by a prime mover interposed between a prime mover and an axle, and a gear type In the transmission having the transmission, the gear-type transmission includes a travel load between an input unit that receives power from the belt-type automatic continuously variable transmission and an output unit that outputs power to the axle. The first gear train that includes a first clutch that is separated when the value is equal to or greater than a predetermined value is different from the first gear train that includes a second clutch that is engaged when the first clutch is separated. And a second gear train having a reduction ratio.

  Further, in the configuration as described in claim 1, as described in claim 2, a traveling load value detection mechanism is disposed on the transmission downstream side of the first and second gear trains, and the first clutch Is engaged / separated based on the value of the traveling load detected by the detection mechanism.

  Further, in the configuration according to claim 1 or 2, as described in claim 3, the first gear train is a high-speed gear train and the second gear train is a low-speed gear train.

  Further, in the configuration as described in claim 1, as described in claim 4, the belt-type automatic continuously variable transmission causes slippage of the belt when overloaded, and the transmission device includes: A rotational speed detecting means for the first shaft on the prime mover side in the belt-type automatic continuously variable transmission; and a rotational speed detecting means for the second shaft on the gear-type transmission side in the belt-type automatic continuously variable transmission, The first clutch is engaged / separated based on the detection value of the both rotation speed detection means.

  Further, in the configuration as described in claim 4, as described in claim 5, the first gear train is a high-speed gear train and the second gear train is a low-speed gear train.

  Further, in the configuration as described in claim 5, when the rotational speed of the first shaft is constant as in claim 6, the second clutch is separated when the engaged first clutch is separated. The shaft rotation speed is set to be smaller than the second shaft rotation speed when the first clutch that has been separated is engaged.

  Further, in the configuration as described in any one of claims 1 to 6, as described in claim 7, the first clutch is a hydraulic clutch.

  Further, in the configuration according to any one of claims 1 to 7, as described in claim 8, the second clutch is an overrunning clutch.

  Further, in the configuration according to any one of claims 1 to 6, as described in claim 9, the first and second clutches are wet disc clutches.

  Further, in the configuration according to any one of claims 1 to 9, as described in claim 10, the idle transmission is separated from the transmission upstream side of the gear-type transmission in the idle rotation speed range of the prime mover. A centrifugal clutch is provided that engages when exceeding several ranges.

  Further, in the configuration according to claim 10, as described in claim 11, when the rotation on the driving side of the centrifugal clutch becomes lower than the rotation on the driven side, the centrifugal clutch is engaged to bypass the centrifugal clutch. Overrunning clutch that transmits power.

  Further, in the configuration as described in claim 10 or 11, as described in claim 12, an adjustment gear train for adjusting the input rotational speed from the prime mover is arranged on the transmission upstream side of the belt type automatic continuously variable transmission. Has been established.

  Moreover, in the structure as described in claim 12, as described in claim 13, the centrifugal clutch is interposed between the adjustment gear train and the belt type automatic continuously variable transmission.

  Alternatively, in the configuration as described in claim 12, as described in claim 14, the centrifugal clutch is interposed between the belt-type automatic continuously variable transmission and the gear-type transmission.

  Further, in the configuration according to any one of claims 1 to 14, as described in claim 15, the switching point between the first gear train and the second gear train regarding the detected traveling load is the first gear train. The travel drive by the two gear trains is set to be in a region slower than 1/2 with respect to the maximum speed of the vehicle.

  Further, in the configuration according to any one of claims 1 to 15, as described in claim 16, the gear-type transmission is configured such that the first and second clutches are not interposed with respect to the output unit. A third gear train capable of selectively outputting rotations having different rotation directions from the one gear train and the second gear train; and a third clutch interposed in the third gear train. .

  Further, in the configuration as set forth in claim 16, as described in claim 17, the third gear train is a reduction gear that is larger than a reduction ratio on the high speed side of either the first gear train or the second gear train. The ratio is set.

  Further, in the configuration as defined in any one of claims 1 to 17, as in claim 18, the belt type automatic continuously variable transmission is disposed on the opposite side of the prime mover across the gear type transmission. Yes.

  Further, in the configuration as set forth in claim 18, as in claim 19, the gear type transmission supports the belt type automatic continuously variable transmission and is mounted in an anti-vibration manner on the frame of the vehicle.

  Further, in the configuration as described in claim 18 or 19, as described in claim 20, the belt-type automatic continuously variable transmission is covered with a cover.

  By configuring the transmission device according to the first aspect of the present invention, the first clutch is automatically engaged / separated in accordance with a change in the running load of the vehicle, and accordingly, the second clutch is separated / engaged. Thus, the reduction ratios appearing by the first gear train and the second gear train are automatically selected.

  Further, by configuring as described in claim 2, the transmission device is provided with a traveling load value detection mechanism, and it is not necessary to add a separate detection means.

  According to the third aspect of the present invention, the gear type transmission is automatically switched between the high / low speed stages, so that a complicated shifting operation can be omitted, and according to the traveling state. A reliable speed stage setting is made.

  According to the fourth aspect of the present invention, the first clutch switching control is performed based on the rotational speeds of the first shaft and the second shaft of the belt type automatic continuously variable transmission. It is not necessary to provide a traveling load detecting means as described in item 2. Therefore, the number of parts is reduced and the transmission device is made compact.

  Further, according to the fifth aspect of the present invention, the gear type transmission is automatically switched between the high / low speed stages, so that a complicated gear shifting operation can be omitted, and according to the traveling state. A reliable speed stage setting is made.

  Further, according to the sixth aspect of the present invention, hysteresis is provided for the switching of the first clutch, so that the automatic switching of the high / low speed stage in the gear type transmission is not performed excessively. I have to.

  Further, by configuring as described in claim 7, it is possible to configure the first clutch that is engaged / separated according to the traveling load.

  According to the eighth aspect of the present invention, the second clutch that is separated / engaged in conjunction with the engagement / separation of the first clutch is configured, and the first gear train and the second gear train are automatically configured. Can be selected.

  Further, by configuring as described in claim 9, both the first and second clutches become wet disk clutches, and these can be combined as an integrated mechanism, resulting in a compact structure. Can be supplied.

  Further, by configuring as described in claim 10, when the prime mover is idling, the centrifugal clutch is disengaged so that a neutral state can be obtained. The tension can be secured and power can be transmitted, and if the prime mover speed exceeds the idle speed even a little, the centrifugal clutch can be run at a low speed.

  Further, when the driven side rotational speed becomes higher than the driving side rotational speed on a downhill or the like, the overrunning clutch is engaged. By avoiding the centrifugal clutch, power transmission to the gear type transmission is ensured via the overrunning clutch, and the engine brake can be effectively operated.

  Further, by configuring as described in claim 12, for example, when selecting either a gasoline engine having a high rotational speed or a diesel engine having a low rotational speed and applying it as a prime mover, the rotational speed as the prime mover. Even when different settings are used, the input rotational speed to the belt-type automatic continuously variable transmission can be kept substantially constant.

  By configuring as in the thirteenth aspect, the belt-type automatic continuously variable transmission, the gear-type transmission on the downstream side of the transmission, and the axle can be brought into a neutral state during idle rotation of the prime mover.

  Alternatively, by configuring as in the fourteenth aspect, at the time of idle rotation of the prime mover, even if the belt type automatic continuously variable transmission is in a driving state, the gear type transmission and the axle can be made neutral. .

  Further, by configuring as described in claim 15, traveling by the first gear train is mainly performed, and at the time of normal start or when climbing a hill of about 30%, for example, efficient traveling drive by the first gear train is performed, The traveling drive in the second gear train can be set so as to be limited to a less frequent situation (for emergency) such as when climbing a steep slope or during heavy towing work.

  Further, by configuring as in the sixteenth aspect, it is possible to select one of two different rotational directions as the output rotational direction to the two axles, and the vehicle can be switched forward and backward.

  Further, according to the structure described in claim 17, traveling by the third gear train is performed more efficiently in the low speed region than traveling by the gear train on the high speed side of the first gear train and the second gear train.

  According to the configuration described in claim 18, the storage structure of the belt type automatic continuously variable transmission can be unified and the cost can be reduced regardless of the change in the specifications of the prime mover.

  According to the nineteenth aspect of the present invention, it is possible to prevent problems caused by vibration in the gear type transmission and the belt type automatic continuously variable transmission in the transmission.

  Further, the belt-type automatic continuously variable transmission can be protected against dust and water by being configured as described in claim 20, and the belt-type automatic continuously variable transmission is sandwiched between the gear-type transmission and the motor. The belt-type automatic continuously variable transmission can be greatly exposed by opening the cover in combination with being located on the opposite side, and is excellent in maintainability. Regardless of changes in the specifications of the prime mover, only one type of cover can be used for the belt type automatic continuously variable transmission.

  1 and 2 show an overall image of a work vehicle (transport vehicle) provided with a transmission device according to the present invention. The schematic structure of this transport vehicle will be described.

  A platform 100b is configured on the body frame 100 of the transport vehicle. A bonnet 100a is mounted in front of the platform 100b. A steering handle 101 for steering the front wheels 104 and 104 is provided above the bonnet 100a. Yes. The rear part of the body frame 100 is one step higher than the platform 100b, and a driver's seat 102 is mounted on the front end upper part and a loading platform 103 is mounted on the rear side.

  The fuselage frame 100 elastically supports (vibration mount) an engine (prime mover) 1 via an anti-vibration rubber (not shown) below the loading platform 103, and a sub-shift in front of the prime mover 1. Like the engine 1, the transmission case 3 that houses the gear-type gearbox is elastically supported (anti-vibration mount) via an anti-vibration rubber (not shown). A CVT case 2 is integrally formed on the front surface of the transmission case 3, and houses a belt type automatic continuously variable transmission (CVT) as a main transmission. The mission case 3 and the CVT case 2 are below the driver's seat 102 as shown in FIG. 1, and the mission case 3 and the CVT case 2 are externally provided for maintenance and the like by enabling the driver's seat 102 to be rotated forward. It is preferable that exposure is possible.

  An engine output shaft 1a protrudes horizontally from the prime mover 1 and a flywheel 1b is provided at the front end thereof. The rear end of the input shaft 4 that protrudes horizontally rearward from the transmission case 3 is connected to the universal joint 4a. And it is connected to the flywheel 1b via the transmission shaft 1c, and the power of the prime mover 1 is transmitted to the input shaft 4.

  At the lower part of the transmission case 3, a rear output shaft 5 protrudes horizontally behind, and a front output shaft 6 protrudes horizontally on the same axis as the rear output shaft 5. The input means to the CVT including the input shaft 4 passes through the mission case 3 forward and is drivingly connected to the CVT in the CVT case 2, and the output of the CVT is a gear-type speed change in the mission case 3. It is transmitted to the front and rear output shafts 5 and 6 via the machine. The gear type transmission has a forward / reverse switching function, and the drive direction of the output shafts 5 and 6 can be switched between a forward direction and a reverse direction.

  Thus, the CVT is arranged on the opposite side of the engine 1 with the mission case 3 interposed therebetween. This makes it possible to unify the design of the CVT case 2 regardless of the multi-specification of the prime mover 1, and the CVT including the input shaft 4 corresponding to each specification of the prime mover 1 in the mission case 3. It is possible to secure a free design space for the input means and the gear type transmission.

  The fuselage frame 100 supports a rear axle housing 10 behind the prime mover 1, and the rear axle housing 10 supports a pair of left and right rear axles 12 and 12, and supports both rear axles 12 and 12. The differential gear mechanism 11 to be differentially connected is housed. Each rear axle 12 is drivingly connected to each rear wheel 105 via universal joints 13 and 13 and a transmission shaft 14 as shown in FIG. 2, and a suspension 15 (coil spring) is connected to each rear wheel 105 from the fuselage frame 100. , An air cylinder, etc.) are connected to support the left and right rear wheels 105 so that the rear axle housing 10 can be moved up and down relatively.

  An input shaft 11a of a differential gear mechanism 11 is projected horizontally from the rear axle housing 10, and the rear output shaft 5 and the input shaft 11a are connected by universal joints 7a and 7b and a transmission shaft 7, The output of the gear type transmission in the mission case 3 is transmitted to both rear wheels 105. The rear transmission shaft 7 is disposed so as to pass through the left and right sides of the prime mover 1 to avoid interference with the prime mover 1 using the universal joints 7a and 7b.

  Further, the fuselage frame 100 supports a front axle housing 16 below the bonnet 100a, and the front axle housing 16 supports a pair of left and right front axles 18 and 18, and both front axles 18 and 18a. A differential gear mechanism 17 for differentially connecting 18 members is housed. Each front axle 18 is drivingly connected to each front wheel 104 via universal joints 19 and 19 and a transmission shaft 20 as shown in FIG. 2, and a suspension 21 (coil spring, air) is connected to each front wheel 104 from the fuselage frame 100. The front axle housing 16 is supported so as to be movable relative to the left and right front wheels 104.

  An input shaft 17a of the differential gear mechanism 17 projects horizontally from the front axle housing 16, and the front output shaft 6 and the input shaft 17a are connected by the universal joints 8a and 8b and the transmission shaft 8, The output of the gear type transmission in the mission case 3 is transmitted to both front wheels 104 and 104.

  Each front wheel 104 is connected to each front axle 18 so as to be steerable. Both front wheels 104 and 104 are connected to each other by a tie rod 9, and the tie rod 9 is operatively connected to the steering handle 101. Thus, the vehicle is steered by turning the front wheels 104 and 104 to the left and right by the turning operation of the steering handle 101.

  Furthermore, operation tools (lever, pedal, etc.) such as a forward / reverse switching operation tool and a brake operation tool (not shown) are arranged on the fuselage frame 100 so that a driver sitting in the driver's seat 102 can operate. .

  3 to 8, the first to third power transmission structures from the input shaft 4 to the output shafts 5 and 6 configured in the CVT case 2 and the transmission case 3 which are integrally configured. Examples will be described. The structures of the adjustment gear train 30 and the hydraulic pump 80 shown in FIG. 5 are commonly used in the transmission devices of the first embodiment of FIG. 3, the second embodiment of FIG. 4, and the third embodiment of FIG. ing. 6 (a) and 6 (b), the structure of the hydraulic clutch type forward high speed clutch 73 and the torque sensor 90, and the structure of the forward low speed gear train 50L including the overrunning clutch type forward low speed clutch 72 shown in FIG. 3 and 4 show the first and second embodiments shown in FIGS. 3 and 4, but the forward high-speed clutch 73, torque sensor 90, and FIG. 7 shown in FIGS. 6 (a) and 6 (b). Each structure of the overrunning forward low speed clutch 72 is used in the third embodiment shown in FIG.

  First, as a structure common to all the embodiments of FIGS. 3 to 8, the CVT case 2 and the transmission case 3 are formed by joining the front case portion 22a, the middle case portion 22b, and the rear case portion 22c in the front and rear directions. Composed. More specifically, the middle case portion 22b has a vertical partition wall 22d in the middle of the front and rear, and a front open internal space in front of the partition wall 22d is defined as a rear space of the CVT case 2, and from the partition wall 22d. The rear open interior space is the front space of the mission case 3, and the CVT case 2 is constructed by joining the rear end of the front case 22a to the front front end of the middle case 22b. The transmission case 3 is configured by joining the opening front end of the rear case portion 22c to the opening rear end of the middle case portion 22b. In addition, it is preferable that joining of case parts is detachable by bolt fastening etc.

  Further, the joint surface between the front case portion 22a and the middle case portion 22b of the CVT case 2 is brought close to the rear side of the CVT 40, that is, the partition wall 22d on the mission case 3 side. When the front case portion 22a is removed from the middle case 22b, the substantially entire portion other than the rear surface of the CVT 40 is exposed. Therefore, a transmission device in which an adjustment gear train 30 and a gear-type transmission 50 (to be described later) are housed in the transmission case 3 (the middle case portion 22b and the rear case portion 22c) can be retrofitted without the CVT 40 being mounted. It can be supplied as a product, and after the CVT 40 is mounted, it is preferable for maintenance such as belt replacement of the CVT 40.

  The front part of the input shaft 4 is inserted from the rear into the rear part of the transmission case 3 constituted by the middle case part 22b and the rear case part 22c, and the insertion part is supported by the bearing part 22e in the transmission case 3. The transmission shaft 23 in the front-rear direction parallel to the input shaft 4 is supported. The transmission shaft 23 has a rear end supported by the rear wall of the transmission case 3 (rear case portion 22 c) and is drivingly connected to an input pulley 41 of a CVT 40 housed in the CVT case 2.

  Further, the transmission shaft 23 is drivingly connected to the input shaft 4 via the adjustment gear train 30 in the mission case 3. That is, the input means to the CVT 40 includes the input shaft 4, the adjustment gear train 30, and the transmission shaft 23. The adjustment gear train 30 in the embodiment shown in FIGS. 3, 4, and 5 has a configuration in which a gear 31 fixed to the input shaft 4 and a gear 32 loosely fitted to the transmission shaft 23 are engaged with each other. Note that a gear 33 for driving a hydraulic pump 80 described later is fixed to the transmission shaft 23 in the vicinity of the gear 32.

  Even when a motor 1 having a different rotational speed setting is used as the prime mover 1 (for example, a diesel engine having a low rotational speed and a gasoline engine having a high rotational speed), the gears of the adjustment gear train 30 can be changed by means such as changing the gear diameter or the number of gears. By adjusting the ratio, the input rotation speed of the CVT 40, that is, the rotation speed of the transmission shaft 23 can be made substantially constant. Thus, by providing the adjustment gear train 30 between the CVT 40 and the prime mover 1, even when the rotational speed setting of the prime mover is different, the input rotational speed of the CVT 40 can be easily adjusted by the gear adjustment of the adjustment gear train 30. Therefore, it is not necessary to replace with a CVT or a gear type transmission having a different setting in accordance with a change in the setting of the prime mover, which contributes to cost reduction.

  Further, as shown in FIG. 5, a gear type hydraulic pump 80 for supplying oil to a forward high speed clutch 73, which will be described later, is attached to the transmission case 3 and driven by the transmission shaft 23. Yes. Further, the hydraulic pump 80 has an optimum discharge amount set according to the rated rotation of the engine having a constant specification, and the discharge amount needs to be constant even when the specification of the prime mover 1 is changed. A gear train corresponding to the rotational speed of the input shaft 4 and the gear ratio of the adjustment gear train 30 is interposed between the transmission shaft 23 driven by the input shaft 4 via the hydraulic pump 80 and the hydraulic pump 80. Yes.

  That is, a pump drive shaft 35 in the front-rear direction parallel to the input shaft 4 and the transmission shaft 23 is supported on the transmission case 3, and the front end thereof is supported by the bearing portion 22 e and fixed to the pump drive shaft 35. The provided gear 34 is meshed with a gear 33 fixed to the transmission shaft 23. The pump drive shaft 35 protrudes rearward from the rear end wall of the transmission case 3 (rear case portion 22c), and is rotatably fitted in a gear pump case 22h fixed to the rear surface of the rear case portion 22c so as to protrude rearward. Has been. A pump driven shaft 39 in the front-rear direction is supported in parallel with the pump drive shaft 35 in the gear pump case 22h, and a gear 37 fixed to the pump drive shaft 35 and a pump driven shaft 39 are fixed. The gear 38 is engaged. Thus, the hydraulic pump 80 housed in the gear pump case 22h is configured.

  Assuming that oil is supplied to the forward high-speed clutch 73 from another hydraulic source, the hydraulic pump 80 shown in FIG. 5 can be replaced with other hydraulic equipment, for example, the carrier 103 shown in FIGS. It is also conceivable to use it for supplying oil to the lifting hydraulic actuator.

  In each of the first to third embodiments shown in FIGS. 3, 4 and 8, the CVT 40 housed in the CVT case 2 has an input whose driving shaft is connected to the transmission shaft 23 (the first shaft of the CVT 40). A V-belt 43 is interposed between the pulley 41 and an output pulley 42 that is drivingly connected to a transmission drive shaft 25 (second shaft of the CVT 40) of the gear-type transmission 50 described later. Further, a torque cam 44 for load control is interposed between the output pulley 42 and the speed change drive shaft 25, and an output subjected to speed change control by the CVT 40 according to the traveling load is transmitted to the speed change drive shaft 25.

  The input pulley 41 is a split pulley, and the belt winding groove width changes with the rotational speed of the transmission shaft 23 (that is, the output rotational speed of the prime mover 1) due to centrifugal force. Along with this, the V belt 43 moves to change the gear ratio between the input pulley 41 and the output pulley 42. As the rotational speed is lower, the groove width of the input pulley 41 becomes wider and the input / output speed ratio is reduced. In this embodiment, even if the rotational speed of the prime mover 1 is in the idle rotational speed range, the speed ratio is reduced. 0 (for example, 0.75), that is, the tension of the V belt 43 is maintained without making the CVT 40 neutral, and a slight driving force is transmitted to the output pulley 42 to prevent the belt 43 from slipping. The life of the belt 43 is extended.

  On the other hand, in order to ensure a neutral state during idle rotation of the prime mover 1, as shown in FIGS. 3 and 4, a centrifugal clutch 70 is disposed on the transmission upstream side of a gear-type transmission 50 described later. . In the first embodiment of FIG. 3, a pulley shaft 41a is pivotally supported in the CVT case 2 in the front-rear direction as the rotation shaft of the input pulley 41, and its rear end protrudes rearward from the partition wall 22d. A centrifugal clutch 70 is interposed between 41 a and the front end of the transmission shaft 23. That is, it is interposed between the prime mover 1 and the CVT 40.

  On the other hand, in the second embodiment of FIG. 4, the centrifugal clutch 70 is interposed between the CVT 40 and the gear type transmission 50, and the pulley shaft 42 a is used as the rotation shaft of the output pulley 42 in the CVT case 2. At the front end of the speed change drive shaft 25 that is supported by a bearing portion 22g provided in the transmission case 30 with the rear end of the pulley shaft 42a protruding rearward from the partition wall 22d. It is connected via a centrifugal clutch 70.

  In the embodiment of FIG. 3, the speed change drive shaft 25 not provided with the centrifugal clutch 70 extends forward, penetrates the partition wall 22d, and is supported in the CVT case 2 as a pulley shaft of the output pulley 42. In the embodiment of FIG. 4, the transmission shaft 23 not provided with the centrifugal clutch 70 extends forward, penetrates the partition wall 22 d, and serves as a pulley shaft of the input pulley 41 in the CVT case 2. I support.

  FIG. 8 shows the integral transmission drive shaft 25 that also serves as the pulley shaft of the driven pulley 42 of the CVT, so that the centrifugal pulley 70 is connected to the CVT 40 (specifically, the pulley of the drive pulley 41 is the same as in FIG. 3). The shaft 41a) is interposed between the transmission shaft 23 and the transmission shaft 23 is omitted, but the specification is changed as shown in FIG. 4 to change the transmission drive shaft 25 and the pulley shaft of the driven pulley 42. Centrifugal pulley 70 may be interposed between 42a and 42a.

  The centrifugal clutch 70 includes a transmission upstream drive member 70a having a weight 70b and a driven downstream drive member 70c. As the rotational speed of the drive member 70a increases, the weight 70b moves in the centrifugal direction due to centrifugal force. It opens and is crimped to the driven member 70c to engage the clutch. By setting the rotation speed of the prime mover 1 corresponding to the engagement / separation timing of the clutch 70 to the maximum value of the idle rotation speed, a neutral state at the time of idle rotation can be secured.

  3 (and FIG. 8), the drive member 70a is fixed to the transmission shaft 23, and the driven member 70c is fixed to the pulley shaft 41a. When the centrifugal clutch 70 is separated, the transmission after the CVT 40 is performed. The system will be in a neutral state. On the other hand, in the embodiment of FIG. 4, the drive member 70a is fixed to the pulley shaft 42a and the driven member 70c is fixed to the speed change drive shaft 25, and the CVT 40 remains in a drivable state when the centrifugal clutch 70 is separated. Thus, the transmission system after the gear type transmission 50 is set to the neutral state.

  3 and 4, the overrunning clutch is provided between the pulley shaft 41a and the transmission shaft 23 or between the pulley shaft 42a and the transmission drive shaft 25 so that the centrifugal clutch 70 can be bypassed. 70d is interposed. When the rotational speed of the driven side (pulley shaft 41a or transmission drive shaft 25) is higher than the drive side rotational speed (transmission shaft 23 or pulley shaft 42a) due to downhill or the like, the overrunning clutch 70d is engaged. Accordingly, the reverse torque transmission from the gear type transmission 50 through the CVT 40 to the prime mover 1 side is ensured by bypassing the centrifugal clutch 70 and the overrunning clutch 70d, and the engine brake can be effectively applied.

  3, 4, and 8, the transmission case 3 houses the transmission mechanism (the transmission shaft 23 and the adjustment gear train 30) from the input shaft 4 to the input portion of the CVT 40, as described above. A gear-type transmission 50 serving as a sub-transmission driven by the power that has been shifted by the CVT 40, and a center that is driven by the output of the gear-type transmission 50 and differentially connects the front and rear output shafts 5 and 6. A differential gear mechanism 60 is housed. The center differential gear mechanism 60 has a differential lock mechanism 66 attached thereto.

  The center differential gear mechanism 60 will be described with reference to FIG. A bull gear 61 that meshes with a final pinion 26a of the speed change driven shaft 26 is fixed to a differential case 62. The front end of the rear output shaft 5 and the rear end of the front output shaft 6 are relatively opposed to the differential case 62 from the front and rear ends. A differential side gear 65 is fixed to each of the rotary gears. A pinion shaft 63 is inserted and locked to the differential case 62 via a locking pin 63a. In the differential case 62, a differential pinion 64 is connected to the pinion shaft 63 so as to be relatively rotatable. 65 is engaged.

  Further, the center differential gear mechanism 60 is provided with a differential lock mechanism 66. The differential lock mechanism 66 is operated from the outside of the transmission case 3 by engaging with a shifter 67 that is slidably provided in the axial direction at the front and rear ends (front end in this embodiment) of the extended differential case 62. A fork (not shown), a lock pin 68 fixed to the shifter 67, and a recess in one of the differential side gears 65 and 65 (in this embodiment, the front differential side gear 65). 65a is formed, and a lock pin 68 that slidably penetrates the differential case 62 can be fitted into the recess 65a.

  When the shifter 67 is set to the differential lock position, the lock pin 68 is fitted into the concave portion 65 a, thereby locking the differential side gear 65 (the rear differential side gear 65 in this embodiment) to the differential case 62. The differential side gear 65 locked to the differential case 62 is also locked to the differential case 62 via the differential pinion 64. In this way, the rear output shaft 5 and the front output shaft 6 are connected so as to be non-differentiable. On the other hand, when the shifter 67 is set to the differential lock release position, the lock pin 68 is disengaged from the recess 65a, and the differential side gear 65 can rotate relative to the differential case 62, so that the rear output shaft 6 and the front output shaft 5 can be differentially operated. It becomes.

  4 and 8, the center differential gear mechanism 60 and the differential lock mechanism 66 are not denoted by the reference numerals of the respective members, but are the same as the structure of FIG. 3. The center differential gear mechanism 60 and the differential lock mechanism 66 shown in FIG. 8 are the same as those shown in FIGS. 3 and 4 arranged in the reverse direction, but depending on the position of the final pinion 26a on the transmission driven shaft 26, The arrangement may be changed as follows.

  3 and 4 uses the common gear-type transmission 50 shown in FIGS. 6A, 6B and 7 as well, and this will be described. A forward high-speed drive gear 25a, a forward low-speed drive gear 25b, and a reverse drive gear 25c are provided around the transmission drive shaft 25 that is pivotally supported in the longitudinal direction in the mission case 30. The forward high speed drive gear 25a is a separate member from the speed change drive shaft 25 and is provided to be rotatable relative to the speed change drive shaft 25. The forward low speed drive gear 25b and the reverse drive gear 25c are integrated with the speed change drive shaft 25. It has been formed. The forward low-speed drive gear 25b and the reverse drive gear 25c may be configured separately from the speed change drive shaft 25 and fixed to the speed change drive shaft 25.

  The forward high-speed drive gear 25a meshes with the forward high-speed driven gear 51 to constitute the forward high-speed gear train 50H, and the forward low-speed drive gear 25b meshes with the forward low-speed driven gear 52 to constitute the reverse low-speed gear train 50L. The reverse drive gear 25c meshes with the reverse driven gear 55 via an idle gear (not shown) (see the idle gear 57 in the embodiment of FIG. 8) to constitute a reverse gear train 50R. Any one of these gear trains 50H, 50L, and 50R is selected, and the rotation of the speed change drive shaft 25 is transmitted to the speed change driven shaft 26 having a final pinion 26a meshing with the bull gear 61 of the center differential gear mechanism 60. .

  The forward high-speed drive gear 25a can be engaged / separated from the transmission drive shaft 25 via a forward high-speed clutch 73 which is a hydraulic clutch provided around the transmission drive shaft 25. The configuration of the forward high speed clutch 73 will be described mainly with reference to FIG. A central boss portion of the clutch main body 73a is fixed to the speed change drive shaft 25. The front and rear intermediate portions of the clutch main body 73a extend in the radial direction and extend from the outer peripheral end of the front and rear intermediate portion in the front and rear direction. A drum-like part is formed.

  An oil chamber surrounded by a drum-shaped portion and a boss portion is provided on the front side and the rear side of the front-rear intermediate portion of the clutch body 73a. That is, the front-rear intermediate portion of the clutch main body 73a is a partition wall between the front oil chamber and the rear oil chamber. The rear end portion of the forward high-speed drive gear 25a is inserted into the front oil chamber so as to extend rearward, and the friction plate 73g engaged with the rearward extension portion of the forward high-speed gear 25a and the drum of the clutch main body 73a. The friction plates 73f engaged with the shape portions are alternately arranged. A piston 73b that is slidable in the axial direction is housed in the rear oil chamber, and a stopper 73c that fixes the rearward sliding limit position of the piston 73b is fixed to the rear end of the drum-like portion of the clutch body 73a. Has been. Further, a disc spring 73d for biasing the piston 73b toward the friction plates 73f and 73g (front side) is interposed between the piston 73b and the stopper 73c in the rear oil chamber.

  Further, a pressing pin 73e that slidably penetrates the partition wall of the clutch body 73a between the friction plate positioned at the rear end of the friction plates 73f and 73g in the front oil chamber and the piston 73b in the rear oil chamber. Is interposed and fixed to the piston 73b. In the rear oil chamber, a hydraulic oil chamber is formed between the piston 73b and the partition wall of the clutch body 73a. In an initial state in which no oil is supplied to the hydraulic oil chamber, the biasing force of the spring 73d The piston 73b and the pressing pin 73e fixed to the piston 73b press the friction plates 73f and 73g together to engage the forward high speed clutch 73.

  The rear end portion of the speed change drive shaft 25 projects rearward from the rear end surface of the rear case portion 22c, and the rear projecting portion slides in the shaft case 22f attached to the rear end surface of the rear case portion 22c in a rearward projecting manner. It is pivotally supported to freely rotate. A hydraulic oil passage 25e is formed in the speed change drive shaft 25 in the axial direction. The hydraulic oil passage 25e opens to the hydraulic oil chamber in front of the piston 73b in the rear oil chamber through the through oil hole of the boss portion of the clutch body 73a, and the rear end thereof is in the shaft case 22f. And communicates with an oil passage from the hydraulic pump 80 through an oil hole formed in the wall portion of the shaft case 22f. The oil passage from the hydraulic pump 80 is configured by piping or the like, and in the middle of the oil passage, a supply position for supplying the oil from the hydraulic pump 80 to the hydraulic oil passage 25e, and the hydraulic oil in the forward high speed clutch 73. A switching valve 81 that is switched to a discharge position for discharging the oil from the chamber and the hydraulic pump 80 to the tank is provided.

  Further, the hydraulic pressure from the switching valve 81 to the hydraulic oil passage 25e is adjusted by the hydraulic pressure adjusting valve 83. When the switching valve 81 is set to the discharge position, the oil passing through the switching valve 81 from the hydraulic oil chamber of the forward high speed clutch 73 is drained through the throttle 81a, so that the friction plates 73f and 73g of the piston 73b The operation for pressure-bonding is eased, and the forward high-speed clutch 73 is loosely engaged. When the switching valve 81 is set to the discharge position, the oil discharged from the hydraulic pump 80 is passed through the switching valve 81 as lubricating oil for the friction plates 73f and 73g and the disc spring 73d to the forward high speed clutch 73. And supply. The lubrication oil pressure adjusting valve 84 adjusts the lubrication oil pressure.

  The speed change drive shaft 25 is provided with a lubricating oil passage 25d parallel to the hydraulic oil passage 25e, and is directed toward the friction plates 73f and 73g in the front oil chamber through the through oil hole of the boss portion of the clutch body 73a. Further, through a through oil hole in the boss portion of the clutch body 73a and an orifice penetrating the piston 73b, toward the oil chamber that houses the disc spring 73d behind the piston 73b in the rear oil chamber. It is open. The rear end of the lubricating oil passage 25d is opened in the shaft case 22f, and the opening end has the through oil hole formed in the wall portion of the shaft case 22f and the above-described discharge position. The oil discharged from the hydraulic pump 80 is received as lubricating oil through the switching valve 81.

  In the forward high-speed clutch 73 as described above, when the switching valve 81 is set to the supply position, oil is supplied to the hydraulic oil chamber formed in the rear oil chamber in the clutch body 73a, and the piston 73b is moved to the disc spring 73d. It slides backward against the urging force to separate the friction plates 73f and 73g, and the forward high speed clutch 73 is separated. When the switching valve 81 is set to the discharge position, the oil is removed from the hydraulic oil chamber, the piston 73b is returned to the initial position by the biasing force of the spring 73d, the friction plates 73f and 73g are pressure-bonded, and the forward high-speed clutch 73 is engaged. Match. In this way, the forward high speed gear train 50H can be engaged / separated from the transmission drive shaft 25 via the forward high speed clutch 73 which is a hydraulic clutch.

  The hydraulic oil in the hydraulic oil chamber is not completely removed even when the switching valve 81 is set to the discharge position, and the oil that cannot be completely removed is a centrifugal pressure caused by the rotation of the speed change drive shaft 25 while the vehicle is running. Thus, the fluid flows into the drum-like portion of the clutch body 73a. For this reason, the piston 73b slightly slides backward, that is, toward the anti-friction plates 73f and 73g, reducing the degree of pressure-bonding between the friction plates 73f and 73g, and lowering the transmission efficiency. Therefore, a vertical plate-like lid plate 73h is provided at the rear end of the forward high-speed clutch 73, and the rear end opening of the oil chamber for housing the disc spring 73d is closed behind the piston 73b, whereby the lubricating oil passage 25d. Further, the oil pressure of the lubricating oil supplied into the storage chamber of the disc spring 73d is increased through the orifice penetrating the piston 73b, and the backward sliding of the piston 73b due to the centrifugal dynamic pressure of the hydraulic oil is suppressed. . Thereby, the original normal pressure-bonding between the friction plates 73f and 73g of the forward high-speed clutch 73 is maintained while the vehicle is traveling, and good transmission efficiency is ensured.

  As shown in FIGS. 3 and 4, the speed change driven shaft 26 is provided with a cylindrical forward driven shaft 27 so as to be relatively rotatable. The forward high speed driven gear 51 is engaged with the rear end of the forward driven shaft 27 so as not to be relatively rotatable. On the other hand, the forward low-speed driven gear 52 is provided around the forward driven shaft 27 so as to be relatively rotatable via a bearing. The forward low-speed driven gear 52 cannot be rotated relative to the forward low-speed driven gear 52 so as to surround the forward driven shaft 27. A cylinder member 52 a that engages with the cylinder is extended forward, and a forward low-speed clutch 72 that is an overrunning clutch is interposed between the cylinder member 52 a and the forward driven shaft 27. Thus, the forward low speed gear train 50L can be engaged / separated with respect to the forward driven shaft 27.

  As shown in FIG. 7 in particular, the forward low-speed clutch 72 has a plurality of sprags 72a arranged radially around the axis of the transmission driven shaft 26, and the rotational speed of the forward driven shaft 27 on the lower transmission side. Becomes lower than the forward low-speed gear 52 (and the cylindrical member 52a) on the transmission upstream side, the sprag 72a rises, and the forward low-speed gear 52 (and the cylindrical member 52a) is relative to the forward driven shaft 27. It is structured to be engaged so as not to rotate. That is, when the forward high speed clutch 73 is separated, the forward driven shaft 27 is not driven by the high speed gear train 50H, and the rotational speed thereof decreases, so that the sprag 72a is automatically raised (the forward low speed clutch 72 is engaged). Match). On the other hand, when the forward high-speed clutch 72 is engaged, the forward driven shaft 27 is driven by the high-speed gear train 50H to increase the rotational speed, thereby causing the sprag 72a to fall (the forward low-speed clutch 72 is separated). Thus, the forward low speed clutch 72 is automatically engaged when the forward high speed clutch 73 is separated, and is automatically separated when the forward high speed clutch 73 is engaged.

  As shown in FIGS. 3 and 4, the reverse driven gear 55 is fixed to the transmission driven shaft 26, and a reverse clutch tooth 55 a is formed at the rear end of the reverse driven gear 55. A spline hub 53 is fixed to the transmission driven shaft 26 between the rear end of the reverse driven gear 55 and the front end of the forward driven shaft 27. Between the spline hub 53 and the forward low-speed driven gear 52, a torque sensor 90 is provided around the forward driven shaft 27, and the forward driven shaft 27 connects the torque sensor 90 and the spline hub 53 to each other. Via the shift driven shaft 26. The final pinion 26a is integrally formed with the shift driven shaft 26 behind the forward driven shaft 27 and the forward high speed driven gear 51 (a separate member may be fixed).

  The torque sensor 90 will be described with reference to FIGS. A forward clutch member 54 is engaged with the front end of the forward driven shaft 27 so as to be relatively rotatable and non-slidable in the axial direction, and forward clutch teeth 54a are formed at the front end. Immediately after the forward clutch member 54, a slider 91 is provided on the forward driven shaft 27 via a roller 93 so as not to be relatively rotatable and slidable in the axial direction. A disc spring 94 is interposed between the slider 91 and the cylindrical member 52 a behind the slider 91 to urge the slider 91 toward the forward clutch member 54. The slider 91 is engaged with a linkage member (fork) 95 that is linked to the operation portion of the switching valve 81 via a link member such as a link rod.

  As can be seen in FIG. 6B, a hemispherical recess 91a for inserting the latter half of the ball 92 is formed on the front surface of the slider 91, and the rear surface of the forward clutch member 54 is opposed to this. In addition, a recess 54b for fitting the front half of the ball 92 is formed. The recess 54b has a hemispherical portion corresponding to the front half of the ball 92, and an extending portion that gradually decreases in the rotational direction around the axis of the transmission driven shaft 26 extends from the hemispherical portion. .

  As will be described later, the spline hub 53 is provided with a shifter 56 that is slidable in the axial direction, and is selected in a state where the shifter 56 is in the forward position and fitted to the forward clutch tooth 54a. The rotational force of the speed change drive shaft 25 is transmitted to the forward driven shaft 27 via either the forward low speed gear train 50L or the forward high speed gear train 50H. Is transmitted to the slider 91, and further to the transmission driven shaft 26 via the ball 92, the forward clutch member 54, the slider 56 fitted to the forward clutch tooth 54a, and the spline hub 53. The slider 91 is pressed against the ball 92 by the urging force of the disc spring 94. During normal running, the ball 92 is the deepest portion of the recess 54b of the forward clutch member 54 as shown in FIGS. The slider 91 rotates substantially integrally with the forward clutch member 54. At this time, the switching valve 81 is in the discharge position, and the forward high speed clutch 73 is engaged.

  When the slider 91 rotates integrally with the forward driven shaft 27 while the shifter 56 engages with the forward clutch teeth 54a, the forward clutch member 54 rotates integrally with the transmission driven shaft 26. Accordingly, when a travel load is applied to the speed change driven shaft 26, the forward clutch member 54 rotates relative to the forward drive shaft 27 together with the speed change driven shaft 26, so that the ball 92 is shallow in the recess 54b. It rides on the portion, pushes the slider 91 backward against the disc spring 94, the switching valve 81 is switched to the supply position, and the forward high speed clutch 73 is separated.

  In this embodiment, the slider 91 is mechanically linked to the switching valve 81. However, the switching valve 81 is an electromagnetic valve type, and the slider 91 slides backward against the disc spring 94. The changeover valve 81 may be operated by a controller (not shown) by detecting the time position with an electric switch.

  The spline hub 53 is provided with a shifter 56 that is slidable in the axial direction. The shifter 56 is attached to the forward clutch teeth 54a by operating the forward / reverse switching operation tool provided on the vehicle. In addition, the spline hub 53 is not fitted to the reverse clutch teeth 55a, and is slid rearward from the neutral position where the spline is fitted only to the spline hub 53. The spline hub 53 is fitted only to the forward clutch teeth 54a. The forward position of the state is slid forward from the neutral position, and the spline hub 53 is switched to three positions of the reverse position in which the spline hub 53 is fitted only to the reverse clutch teeth 55a.

  3 and 4, for the sake of convenience, the state of the shifter 56 in the neutral position is illustrated above the shift driven shaft 26, and the state of the shifter 56 in the forward position is illustrated below the shift driven shaft 26.

  When the shifter 56 is in the forward movement position, the forward driven shaft 27 is engaged with the speed change driven shaft 26 so as not to be relatively rotatable, and the forward high speed clutch and the forward low speed clutch are automatically engaged / separated as will be described later. Either the gear train 50H or the forward low-speed gear train 50L is drivingly connected to the forward driven shaft 27 to cause the transmission driven shaft 26 to rotate forward. On the other hand, when the shifter 56 is in the reverse drive position, the reverse drive gear 55 is engaged with the speed change driven shaft 26 so as not to be relatively rotatable, and the speed change driven shaft 26 is rotated backward.

  As will be described in detail later with reference to FIG. 10, the forward low speed clutch 72 and the forward high speed clutch 73 are set to be engaged / separated against each other. Accordingly, when the forward high speed clutch 73 is engaged in the state where the shifter 56 is in the forward position, the forward high speed drive gear 25a is engaged with the transmission drive shaft 25 so as to be integrally rotatable, and the forward high speed gear train 50H is In the forward low-speed gear train 50L, as long as the speed change drive shaft 25 is rotating, the rotation is forwardly driven at a low speed fixed to the speed change drive shaft 25. Although the forward low speed driven gear 52 is transmitted from the gear 25b to the forward low speed driven gear 52, the forward low speed clutch 72 is disengaged, so that the forward low speed driven gear 52 idles so as to rotate relative to the shift driven shaft 26 and the forward driven shaft 27. ing.

  On the other hand, when the forward low-speed clutch 72 is engaged, the forward low-speed driven gear 52 that is constantly receiving the rotational force of the speed change drive shaft 25 is engaged with the forward driven shaft 27, via the forward low-speed gear train 50L. While the rotational force of the speed change drive shaft 25 is transmitted to the speed change driven shaft 26, in the forward high speed gear train 50H, the rotation of the forward high speed driven gear 51 that rotates together with the forward driven shaft 27 is transmitted to the forward high speed gear 25a. However, since the forward high-speed clutch 73 is separated, the forward high-speed gear 25 a is idled so as to rotate relative to the transmission drive shaft 25 by the power from the transmission driven shaft 26. Thus, due to the reverse engagement / separation of the forward low-speed clutch 72 and the forward high-speed clutch 73, one of the forward high-speed gear train 50H and the forward low-speed gear train 50L is being driven by the other selected. , Are idle.

  Next, the structure of the gear type transmission 50 in the third embodiment of FIG. 8 will be described. In the transmission case 3, a parallel counter shaft 28 is rotatably supported between the speed change drive shaft 25 and the speed change driven shaft 26, and the high speed gear train 50H and the low speed gear train 50L are speed change driven. The shaft 25 and the counter shaft 28 are interposed in parallel.

  As for the high-speed gear train 50H, like the forward high-speed gear train 50H in the embodiment of FIGS. 3 and 4, a high-speed drive gear 25a is provided on the transmission drive shaft 25 so as to be relatively rotatable. A hydraulic clutch type high speed clutch 73 for engaging / separating the high speed drive gear 25a with respect to the speed change drive shaft 25 is provided. The high-speed drive gear 25a is directly meshed with a counter gear 28a fixed to the counter shaft 28. That is, the high-speed gear train 50H includes a high-speed drive gear 25a and a counter gear 28a, and can be engaged / separated with respect to the transmission drive shaft 25 via the high-speed clutch 73.

  On the other hand, the low-speed gear train 50L includes a forward low-speed driven gear 28b that is provided around the counter shaft 28 via a low-speed clutch 72 having an overrunning clutch structure, and a low-speed drive gear 25b that is fixed (integrally formed) with the transmission drive shaft 25. It has a meshed configuration.

  Similar to the embodiment of FIGS. 3 and 4, the high speed clutch 73 and the low speed clutch 72 are engaged / separated in a contradictory manner. As long as the speed change drive shaft 25 rotates, the low speed driven gear 28b receives rotational force from the low speed drive gear 25b fixed to the speed change drive shaft 25. When the high speed clutch 73 is engaged, transmission from the speed change drive shaft 25 to the counter shaft 28 is performed via the high speed clutch 73 and the gears 25a and 28a. However, since the low speed clutch 72 is separated, the low speed driven gear 28b The rotation is not transmitted to the counter shaft 28, and therefore the rotation does not oppose the transmission from the speed change drive shaft 25 to the counter shaft 28 via the high speed clutch 73 and the gears 25a and 28a.

  When the low speed clutch 72 is engaged, the rotation of the low speed driven gear 28 b is transmitted to the counter gear 28 a via the counter shaft 28. The rotation of the counter gear 28a is also transmitted to the high-speed drive gear 25a meshing with the counter gear 28a. However, since the high-speed clutch 73 is separated at this time, the rotation of the high-speed drive gear 25a is not transmitted to the transmission drive shaft 25. The rotation of the speed change drive shaft 25 is not hindered.

  Between the counter shaft 28 and the transmission driven shaft 26, a forward gear train 50F and a reverse gear train 50R are interposed in parallel. The forward gear train 50F is configured by directly meshing the counter gear 28a and the forward driven gear 29 that is provided so as to be rotatable relative to the transmission driven shaft 26, while the reverse gear train 50R is configured by the counter shaft 28. The reverse drive gear 28 c fixed to the transmission drive shaft and the reverse drive gear 55 provided so as to be rotatable relative to the speed change drive shaft 26 are engaged with each other via an idle gear 57.

  A boss portion of the forward driven gear 29 is rearwardly extended on the speed change driven shaft 26, and the hydraulic control switching valve 81 to the hydraulic high speed clutch 73 having a configuration as shown in FIG. Torque sensor 90 (including the forward clutch member 54). A spline hub 53 is fixed to the transmission driven shaft 26 between the rear end of the boss portion of the forward driven gear 29 and the backward driven gear 55 arranged behind the forward driven gear 29, and the spline hub 53 has an axial direction. A shifter 56 is provided so as to be slidable. The shifter 56 is a forward / reverse switching operation tool of the vehicle, and a forward position where only the forward clutch tooth 54a of the forward clutch member 54 of the spline hub 53 and torque sensor 90 is engaged, and the spline hub 53 and the backward driven gear 55. The position is switched between a reverse position that meshes only with the forward clutch teeth 55a and a neutral position that is separated from both clutch teeth 54a and 55a. For the sake of convenience, FIG. 8 shows the shifter 56 in the forward position on the upper side of the transmission driven shaft 26 and the shifter 56 in the neutral position on the lower side.

  Power from the speed change drive shaft 25 is transmitted to the counter shaft 28 via either the high speed gear train 50H or the low speed gear train 50L when the high speed clutch 73 and the low speed clutch 72 are engaged / separated. When the shifter 56 is in the forward position, the forward gear train 50F is drivingly connected to the transmission driven shaft 26 via the torque sensor 90, so that the switching valve 81 is switched according to the change in the state of the torque sensor 90 as described above. Then, the engagement / separation control of the high speed clutch 73 and the low speed clutch 72 is performed, and the high speed traveling by the high speed gear train 50H or the low speed traveling by the low speed gear train 50L is automatically selected.

  On the other hand, when the shifter 56 is in the reverse drive position, the reverse gear train 50R is drivingly connected to the speed change driven shaft 26 without passing through the torque sensor 90. Since the forward clutch member 54 of the torque sensor 90 is separated from the shifter 56 that can rotate integrally with the transmission driven shaft 26 via the spline hub 53, even if a traveling load is applied to the transmission driven shaft 26, the transmission driven shaft 26, the ball 92 is inserted into the deepest portion of the recess 54b by the biasing force of the disc spring 94 on the slider 91 side, and therefore the switching valve 81 is not rotated. Is kept in the discharge position, and the high-speed clutch 73 remains engaged at all times. That is, during reverse travel, the rotation of the speed change drive shaft 25 is transmitted to the counter shaft 28 only via the forward high speed gear train 50H, and the power of the counter shaft 28 is transmitted to the speed change driven shaft 26 via the reverse gear train 50R. Is.

  Further, in the embodiment of FIG. 8, the front output shaft 6 is divided into an internal front output shaft 6a and an external front output shaft 6b arranged in parallel, and the configuration of the CVT case 2 of the middle case portion 22b. The front end of the internal front output shaft 6a and the rear end of the external front output shaft 6b are pivotally supported in a gear case 22i attached in a forward projecting manner to the front end surface that is separated from the portion, and the internal front output shaft 6a A gear 6c fixed to the outer front output shaft 6b and a gear 6e fixed to the external front output shaft 6b are engaged via an idle gear 6d. In this way, the external front output shaft 6b is disposed at a suitable position with respect to the front axle case 16 as shown in FIGS. 1 and 2, and the external output shaft 6b is connected to the differential gear mechanism 17 in the front axle case 16. The transmission system structure including the transmission shaft can be simplified, contributing to low cost. In addition, when a universal joint is used, the bending angle can be reduced, and effects such as improvement of transmission efficiency and noise reduction can be obtained. Also, the external output shaft 6b and the input shaft 17a are on the same axis. In the case where it can be arranged, the cost can be further reduced by eliminating the universal joint.

  The gear type transmission 50 in the fourth embodiment shown in FIG. 9 is a modification of the one shown in FIG. 8, and in the speed change drive shaft 25, the high speed drive gear 25a and the low speed drive gear 25b are rotated forward and backward relative to each other. A hydraulic clutch mechanism 74 is provided around the speed change drive shaft 25 between the gears 25a and 25b. Correspondingly, a counter gear 28a and a low-speed driven gear 28b are fixed to the counter shaft 28 in a front-rear distribution manner, and meshed with the high-speed drive gear 25a and the low-speed drive gear 25b, respectively. . Thus, a high-speed gear train 50H that can be connected to the transmission drive shaft 25 via the high-speed clutch 74H and a low-speed gear train 50L that can be connected to the transmission drive shaft 25 via the low-speed clutch 74L are configured. . A forward gear train 50 </ b> F via the torque limiter 90 that can be alternatively engaged with the speed change driven shaft 26 by the shifter 56 between the counter shaft 28 and the speed change driven shaft 26, and the reverse drive without the torque limiter 90. A gear train 50R is interposed as in FIG.

  The hydraulic clutch mechanism 74 has a clutch main body 74a. The clutch main body 74a has a central boss portion fixed to the transmission drive shaft 25, and the front and rear central portions of the boss portion extend in the radial direction. A drum-like portion extending from the outer peripheral end to the front and rear is formed. The clutch body 74a has an oil chamber surrounded by a drum-like portion and a boss portion on the front and rear sides, respectively, with the radially extending front and rear central portions as partition walls.

  The rear end portion of the high-speed drive gear 25a disposed in front of the hydraulic clutch mechanism 74 is inserted into the front oil chamber so as to extend rearward, and the drum-like portion of the clutch body 74a is inserted in the front oil chamber. The friction plate 74d engaged with the friction plate 74 and the friction plate 74e engaged with the rearward extending portion of the high-speed drive gear 25a are alternately arranged to constitute a high-speed clutch 74H as a wet disk clutch. Further, in the front oil chamber, the piston 74b moves in the axial direction (front-rear direction) between the front and rear central partition walls of the clutch body 74a and the friction plate 74d / 74e group located at the rear end. ) And a spring 74c for urging the piston 74b rearward, that is, on the side opposite to the friction plates 74d and 74e (the side away from the friction plates 74d and 74e). Yes.

  The operation of the front oil chamber between the piston 74b and the front and rear central partition walls of the clutch body 74a to push the piston 74b forward, that is, to the friction plates 74d and 74e (the pressure bonding side of the friction plates 74d and 74e). The hydraulic oil chamber is supplied with oil, and a through hole in the boss portion of the clutch body 74a is formed in the hydraulic oil chamber from a hydraulic oil passage 25e similar to that shown in FIG. The hydraulic oil is supplied through this. Further, in the front oil chamber, the friction chambers 74d and 74e and the spring 74c in the front chamber of the piston 74b are placed in the boss of the clutch body 74a by a lubricating oil passage 25d formed in the speed change drive shaft 25 as in FIG. Lubricating oil is supplied through the through hole of the part.

  A front end portion of a low-speed drive gear 25b disposed rearward of the hydraulic clutch mechanism 74 is inserted into the rear oil chamber of the clutch main body 74a so as to extend forward, and the clutch main body is inserted in the rear oil chamber. The friction plate 74f engaged with the drum-like portion 74a and the friction plate 74g engaged with the forward extension portion of the low-speed drive gear 25b are alternately arranged to constitute a low-speed clutch 74L as a wet disk clutch. Yes. A pressing plate 74j is disposed so as to be slidable in the axial center (front-rear) direction immediately before the frontmost portion of the friction plates 74f and 74g. Further, the lubricating oil for the friction plates 74f and 74g is supplied from the lubricating oil passage 25d to the rear oil chamber through the through hole of the boss portion of the clutch body 74a.

  Further, the interlocking pin 74k passes through the drum-like portion of the clutch body 74a so as to be slidable in the axial center (front-rear) direction, and the front end thereof is fixed to the piston 74b and the rear end thereof is fixed (or pressed) to the pressing plate 74j. )is doing. Thus, the low-speed clutch 74L and the high-speed clutch 74H are interlocked so as to be engaged / separated against each other.

  When the hydraulic circuit of FIG. 6 is applied to the embodiment of FIG. 9, the relationship between the discharge position / supply position of the switching valve 81 and the operation / non-operation of the torque limiter 90 is opposite to that shown in FIG. Should be. That is, when the torque limiter 90 does not detect an excessive traveling load, the switching valve 81 is in the supply position, the hydraulic oil is supplied to the hydraulic oil chamber, the piston 74b slides forward, and the friction plate 74d. 74e is crimped and the high-speed clutch 74H is engaged. At this time, the interlocking pin 74k is at the front end position of the sliding area, and the pressing plate 74j is separated from the friction plates 74f and 74g. 74f and 74g are separated from each other, and the low speed clutch 74L is separated. When the excessive travel load is detected and the torque limiter 90 is activated, the switching valve 81 is shifted to the discharge position, the oil is removed from the hydraulic oil chamber, and the piston 74b slides backward to disengage the friction plates 74d and 74e. At the same time, the friction pins 74f and 74g are pressed against each other by sliding the interlocking pin 74k and the pressing plate 74j together with the piston 74b, and the high speed clutch 74H is disconnected and the low speed clutch 74L is engaged.

  Even if the clutches 74H and 74L are not mechanically connected by the interlocking pin 74j or the like, the clutches 74H and 74L may be electrically engaged with each other and engaged / separated in a contradictory manner. Good.

  Further, as shown in FIG. 9, the hydraulic clutch mechanism 74 having the high speed clutch 74H and the low speed clutch 74L, which are wet disk clutches, is provided between the speed change drive shaft 25 and the forward driven shaft 27 as shown in FIGS. It can also be applied as a clutch mechanism for the forward high-speed gear train 50H and the forward low-speed gear train 50L.

  3, 4, 8, and 9, the driving characteristics by clutch control in the gear-type transmission 50 of the transmission in FIGS. 3 and 4, that is, the vehicle speed (Ground). The relationship between the (Speed) GS and the driving force (Traction Effect) TE corresponding to the traveling load will be described with reference to FIG.

  First, in the graph of FIG. 10, the value of the vehicle speed GS assumes that the reverse speed is negative and the forward speed is positive. In FIG. 10, graph L shows the running characteristics of the forward low speed gear train 50 </ b> L obtained by setting the shifter 56 to the forward position and engaging the forward low speed clutch 72, and graph H shows the shifter 56 in the forward position and the forward high speed clutch 73. The graph R represents the travel characteristics of the reverse gear train 50R obtained by engaging the reverse clutch, that is, the shifter 56 in the reverse position.

  The traveling drive by the forward low speed gear train 50L is limited to the case of climbing a steep slope (over 30%), heavy traction work, or the like. The torque sensor 90 is set to be maintained at the discharge position during a normal start or a traveling load when climbing a slope of about 30% or less (that is, the traveling load in these cases is not considered excessive). ing.

  That is, the point of driving force (running load) for operating the torque sensor 90 to switch the switching valve 81 from the discharge position to the supply position is set to TH → L, and this point is about 30% at the time of the normal start described above. It is set to a value higher than the driving force corresponding to the running load when climbing the slope. As long as the traveling load (driving force TE) does not increase from TH to L, as shown in the graph H, the traveling drive through the forward high-speed gear train 50H by the engagement of the forward high-speed clutch 73 enables efficient high-speed traveling. Is possible. When the traveling load (driving force TE) increases from TH to L when climbing a steep slope (over 30%) or during heavy towing work, the engagement of the forward low-speed clutch 72 as shown in the graph L. Due to the traveling drive through the forward low-speed gear train 50L, it is possible to travel at a low speed while maintaining a high driving force TE.

  Further, a travel point for switching from travel drive by the forward low-speed gear train 50L to travel drive by the forward high-speed gear train 50H, that is, travel for returning the torque sensor 90 to the initial position and returning the switching valve 81 at the supply position to the discharge position. The point TL → H of the load (driving force TE) is set at a position where the traveling load (driving force TE) is lower than the point TH → L, thereby generating a hysteresis and the traveling load near the switching point. Is stabilized (over-frequency clutch switching is avoided). In other words, even if the traveling load increases from the state where the gear type transmission 50 is set to the high speed stage (the high speed clutch 73 is engaged and the low speed clutch 72 is separated), the value remains within the hysteresis region. Only when the high speed is maintained and becomes higher than the hysteresis region, the low speed stage (the high speed clutch 73 is disengaged and the low speed clutch 72 is engaged) is switched, and the gear type transmission 50 is set to the low speed stage. Even if the traveling load decreases, the low speed stage is maintained while the value stays within the hysteresis range, and the low speed stage is switched to the high speed stage only when the travel load is lower than the hysteresis range.

  With the above settings, the region of the vehicle speed GS obtained by the forward low-speed gear train 50L is set lower than 1/2 of the maximum value of the vehicle speed, and the frequency of the traveling drive by the forward low-speed gear train 50L is suppressed. As for the traveling, the fuel efficiency is ensured on the assumption that efficient traveling drive is performed by the forward high-speed gear train 50H.

  When the reverse clutch is engaged, that is, when the shifter 56 is in the reverse position, the torque sensor 90 does not intervene in the transmission system to the transmission driven shaft 26, and the reverse gear train 50R is higher than the vehicle speed GS during reverse. The driving force TE is set so as to obtain, for example, substantially the same as the characteristic of the driving force TE by the forward low-speed gear train 50L set with respect to the vehicle speed GS at the time of forward traveling. The driving characteristic TE is substantially line symmetrical with the traveling characteristic curve L by the forward low-speed gear train 50L with the driving force TE) in between. That is, a speed range that is slower than the speed range obtained by the forward high-speed gear train during normal travel is ensured.

  8 and 9, the traveling characteristics shown by the graphs L and H in FIG. 10 appear during forward travel, while the transmission to the variable speed driven shaft 26 during reverse travel. The torque characteristic is not caused by the torque sensor 90 in the system, and the traveling characteristics are obtained by traveling driving through the high speed gear train 50H and the reverse gear train 50R.

  In each of the above-described embodiments, the detection of the traveling load related to the switching of the clutches 72 and 73 is performed for the (forward) low-speed gear train 50L and the (forward) high-speed gear train 50H in the gear-type transmission 50 provided in the mission case 3. A mechanical torque sensor 90 provided on the downstream side of the transmission is used. Instead, a detection device that detects a torque of a certain value or more using a strain gauge or the like is provided on the downstream side of the transmission of the gear transmission 50. A detection device is installed to detect that the engine rotational speed for installation or a certain set output rotational speed exceeds a certain value, and based on the detection, the controller switches the electromagnetic switching valve 81 from the discharge position. It is good also as what switches to a supply position.

  Next, a fifth embodiment shown in FIGS. 11 to 14 will be described. Since the CVT 40 slips between the V belt 43 and the input pulley 41 or the output pulley 42 when a load exceeding the load that can be transmitted is applied, the rotational speed of the first shaft (the transmission shaft 23) that is drivingly connected to the prime mover. The rotational speed of the second shaft (transmission drive shaft 25) is lower than the original rotational speed corresponding to the reduction ratio of the CVT 40. Therefore, in this embodiment, instead of detecting the load by the torque sensor 90, the engagement of the high speed clutch 73 is based on the detection of the rotational speeds of the first shaft (transmission shaft 23) and the second shaft (transmission drive shaft 25) of the CVT 40. This controls the separation and separation. Thereby, the torque sensor 90 can be made unnecessary. FIG. 11 shows a rotation speed sensor 82 for detecting the rotation speed of the transmission shaft 23 attached to the transmission case 3 (rear case portion 22c), and FIG. 12 shows a speed change attached to the transmission case 3 (rear case portion 22c). A rotation speed sensor 82a for detecting the rotation speed of the drive shaft 25 is illustrated.

  Note that the maps shown in FIGS. 13 and 14 are applied to control the engagement / separation control of the high speed clutch 73 based on the detection of the first and second shaft rotation speeds of the CVT 40 in order to reveal hysteresis. It is. First, FIG. 13 will be described. About CVT40, it sets so that it may change between the value represented by the characteristic curve 101, and the value represented by the characteristic curve 102 about the 2nd axis | shaft rotational speed Rs with respect to the 1st axis | shaft rotational speed Rp. ing. (In other words, when the first shaft rotational speed Rp is constant, the second shaft rotational speed Rs is a maximum value set by the characteristic curve 101 and a minimum value set by the characteristic curve 102. Change between.)

  The second shaft rotational speed Rs for separating the engaged high speed clutch 73 is lower than the value represented by the characteristic curve 102 and is represented by the characteristic curve 103. The characteristic curve 103 may be substantially parallel to the characteristic curve 102. When the rotational speed of the first shaft (transmission shaft 23) that rotates substantially integrally with the prime mover output shaft 1a is the maximum (rated) rotational speed Rpa, the engaged high-speed clutch 73 is the second shaft (transmission drive shaft 25). Are separated when the rotation speed becomes lower than Rsa. That is, in FIG. 13, when the first shaft rotation speed Rp and the second shaft rotation speed Rs of the CVT 40 are within the region A, the gear type transmission 50 is always set to the low speed stage.

  The second shaft rotation speed Rs for engaging the separated high speed clutch 73 is higher than the value represented by the characteristic curve 102 and is represented by the characteristic curve 104. The characteristic curve 104 may also be substantially parallel to the characteristic curve 102. However, when the first shaft rotation speed Rp is lower than the initial rotation speed Rpb and is in the idle rotation speed range Rpi, the gear type transmission 50 is uniformly set to the high speed regardless of the second shaft rotation speed Rs. This characteristic curve 104 is applied when the first shaft rotational speed Rp is equal to or higher than the initial rotational speed Rpb. When the rotation speed of the first shaft (transmission shaft 23) is the maximum rotation speed Rpa, the separated high speed clutch 73 is engaged when the rotation speed of the second shaft (transmission drive shaft 25) becomes higher than Rsb. . That is, in FIG. 13, when the first shaft rotation speed Rp and the second shaft rotation speed Rs of the CVT 40 are in the region B, the gear type transmission 50 is always set to the high speed stage.

  In FIG. 13, a region C between the region A and the region B with respect to the CVT first shaft rotation speed Rp and the second shaft rotation speed Rs is a hysteresis region. Even if the second shaft rotation speed Rs in the region B decreases to the hysteresis region C, the high speed clutch 73 remains engaged. The machine 50 is in the low speed stage. On the other hand, even if the second shaft rotation speed Rs in the region A increases to the hysteresis region C, the high speed clutch 73 remains separated. The transmission 50 is in a high speed stage.

  FIG. 14 is based on the assumption that the speed stage of the gear-type transmission 50 is set with respect to the detected values of the CVT first shaft rotation speed Rp and the second shaft rotation speed Rs as shown in FIG. The relationship of the speed stage of the gear type transmission 50 with respect to the CVT second shaft rotation speed Rs when the shaft (transmission shaft 23) is driven at the maximum (rated) rotation speed Rpa is shown. When the gear type transmission 50 is set to the high speed stage Hi, even if the second shaft rotational speed Rs is lower than Rsb, the high speed stage Hi is maintained if the second shaft rotational speed Rs is higher than Rsa, and the second shaft rotational speed Rs is When it becomes lower than Rsa, it switches to the low speed stage Lo. On the other hand, when the gear-type transmission 50 is set to the low speed stage Lo, even if the second shaft rotational speed Rs is higher than Rsa, if the speed is lower than Rsb, the low speed stage Lo remains. When Rs becomes higher than Rsb, the high-speed stage Hi is switched.

  The above is a recommended example of the present invention, and details such as the combination and arrangement of the members can be changed without departing from the scope of the claims.

It is a side view of a work vehicle (transport vehicle) to which the present invention is applied. It is a top view of this work vehicle. 1 is a plan sectional view of a transmission device according to a first embodiment of the present invention. It is a plane sectional view of the transmission concerning a 2nd example of the present invention. It is side surface sectional drawing of the adjustment gear row | line | column part in a mission case. (A) is sectional drawing and hydraulic circuit diagram which show the related structure of a hydraulic advance high speed clutch and a torque sensor, (b) is a fragmentary sectional view of the rotation direction of this torque sensor. It is a rear surface sectional view of a forward low-speed gear train including a forward low-speed clutch in a mission case. It is a fragmentary top sectional view of the transmission which concerns on 3rd Example of this invention. It is a fragmentary top sectional view of the transmission which concerns on 4th Example of this invention. It is a graph which shows the change of the driving force with respect to the vehicle speed by clutch control of the transmission which concerns on this invention. Rotation of the first shaft in the transmission device according to the fifth embodiment of the present invention, in which the traveling load detection is replaced with the rotation speed detection of the first and second shafts of the CVT to control the clutch of the gear transmission. It is a partial rear surface sectional view of a number sensor attachment part. Rotation of the second shaft in the transmission device according to the fifth embodiment of the present invention having a structure for performing clutch control of the gear-type transmission by replacing the running load detection with the rotation speed detection of the first and second shafts of the CVT. It is a partial rear surface sectional view of a number sensor attachment part. It is a figure which shows the speed stage setting map of the gear type transmission with respect to the rotation speed detection value of the 1st axis | shaft of CVT in the transmission which concerns on this 5th Example, and a 2nd axis | shaft. It is a figure which shows the speed stage setting map of the gear type transmission with respect to a CVT 2nd axis | shaft at the time of setting as shown in FIG.

Explanation of symbols

1 Motor 2 CVT Case 3 Mission Case 4 Input Shaft 5 Rear Output Shaft 6 Front Output Shaft 23 Drive Shaft 25 Drive Shift Shaft 26 Shift Drive Shaft 27 Forward Drive Shaft 30 Adjusting Gear Train 40 CVT (Belt Type Automatic Continuously Variable Transmission ( Main transmission))
50 Gear type transmission (sub transmission)
50H Forward high-speed gear train 50L Forward low-speed gear train 50R Reverse gear train 60 Center differential mechanism 70 Centrifugal clutch 72 (Overrunning type) Forward low-speed clutch (low-speed clutch)
73 (Hydraulic) Advance high speed clutch (High speed clutch)
82 First shaft speed sensor 82a Second shaft speed sensor 90 Torque sensor

Claims (20)

  In a transmission device having a belt-type automatic continuously variable transmission interposed between a prime mover and an axle and driven by the prime mover, and a gear-type transmission, the gear-type transmission includes the belt-type automatic transmission. A first gear train that includes a first clutch that is separated when the traveling load is a predetermined value or more between an input unit that receives power from the continuously variable transmission and an output unit that outputs power to the axle. And a second gear train having a reduction ratio different from that of the first gear train, which is provided with a second clutch that is engaged when the first clutch is separated. .   A travel load value detection mechanism is disposed on the transmission downstream side of the first and second gear trains, and the first clutch is engaged / separated based on the travel load value detected by the detection mechanism. The transmission device according to claim 1, wherein:   The transmission device according to claim 1 or 2, wherein the first gear train is a high speed gear train and the second gear train is a low speed gear train.   In the belt type automatic continuously variable transmission, the belt slips when an overload is applied, and the transmission device detects the rotational speed of the first shaft on the prime mover side in the belt type automatic continuously variable transmission. And a rotational speed detecting means for the second shaft on the gear-type transmission side in the belt-type automatic continuously variable transmission, and the first clutch is engaged based on the detected value of the rotational speed detecting means. The transmission according to claim 1, wherein the transmission is separated.   The transmission device according to claim 4, wherein the first gear train is a high-speed gear train and the second gear train is a low-speed gear train.   When the rotational speed of the first shaft is constant, the second shaft rotational speed when the engaged first clutch is separated is the second rotational speed when the separated first clutch is engaged. The transmission device according to claim 5, wherein the transmission device is smaller than the biaxial rotation speed.   The transmission device according to any one of claims 1 to 6, wherein the first clutch is a hydraulic clutch.   The transmission device according to any one of claims 1 to 7, wherein the second clutch is an overrunning clutch.   The transmission device according to any one of claims 1 to 6, wherein the first and second clutches are wet disk clutches.   2. A centrifugal clutch that is separated in an idle rotation speed range of the prime mover and engages when the transmission speed exceeds the idle rotation speed range is disposed upstream of the transmission of the gear type transmission. The transmission device according to any one of 9.   11. An overrunning clutch that engages and bypasses the centrifugal clutch to transmit power when rotation on the driving side of the centrifugal clutch becomes lower than rotation on the driven side. The transmission device described in 1.   The transmission device according to claim 10 or 11, wherein an adjustment gear train for adjusting an input rotational speed from the prime mover is disposed on the transmission upstream side of the belt-type automatic continuously variable transmission.   The transmission device according to claim 12, wherein the centrifugal clutch is interposed between the adjustment gear train and the belt-type automatic continuously variable transmission.   The transmission device according to claim 12, wherein the centrifugal clutch is interposed between the belt-type automatic continuously variable transmission and the gear-type transmission.   The switching point between the first gear train and the second gear train relating to the detected travel load is such that the travel drive by the second gear train is in a region slower than 1/2 with respect to the maximum speed of the vehicle. The transmission device according to claim 1, wherein the transmission device is set.   The gear-type transmission can selectively output rotation having a rotation direction different from that of the first gear train or the second gear train to the output unit without passing through the first and second clutches. The transmission device according to any one of claims 1 to 15, further comprising a third gear train and a third clutch interposed in the third gear train.   The transmission device according to claim 16, wherein the third gear train is set to a speed reduction ratio that is larger than a speed reduction ratio of either the first gear train or the second gear train on a high speed side.   The transmission device according to any one of claims 1 to 17, wherein the belt-type automatic continuously variable transmission is disposed on the opposite side of the prime mover with the gear-type transmission interposed therebetween.   19. The transmission device according to claim 18, wherein the gear type transmission supports the belt type automatic continuously variable transmission and is mounted in a vibration-proof manner with respect to a vehicle frame. The transmission device according to claim 18 or 19, wherein the belt-type automatic continuously variable transmission is covered with a cover.

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