JP3727218B2 - Tractor transmission structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission structure for a tractor in which a space case is interposed between a mission case and a differential case.
[0002]
[Prior art]
The introduction of the space case described above is used to increase the distance between the front and rear wheels (foil base) and increase the number of gears without changing the basic structure of the transmission case. The case was provided with a bearing portion and the like for supporting the transmission gear mechanism (for example, JP-A-63-304904).
[0003]
[Problems to be solved by the invention]
If it does so, a space case will bear a part of load, and it is necessary to take the intensity | strength structure equivalent to it, and there existed a possibility that a space case might become sturdy and heavy.
[0004]
An object of the present invention is to provide a space case capable of simplifying the structure and reducing the weight in consideration of the fact that the space case is used in an auxiliary manner.
[0005]
[Means for Solving the Problems]
(Configuration) According to the first aspect of the present invention, a transmission case is configured by interposing a space case between a transmission case and a differential case, and a transmission gear mechanism is housed in the transmission case, and the transmission gear mechanism is switched. the shift shifter and manipulating slidably supported on the shift shift shaft, both axial ends of the transmission shift shaft located at a point which supports the bearing wall and the bearing wall of the differential case of the transmission case, the effects thereof Is as follows.
[0006]
(Operation and Effect) In other words, by receiving the operation force from the shift operation device, both axial ends of the transmission shift shaft shifting shifter for switching the speed change gear mechanism is slidably supported on the bearing wall of the bearing wall and the differential case of the transmission case Since it is supported, it is not necessary to provide a structure for supporting the transmission shift shaft in the space case, and it is not necessary to reinforce in terms of strength, and weight reduction can be achieved.
In addition, the transmission case and differential case originally required a structure for supporting the transmission shaft, etc., and had sufficient strength to cope with it, so that a bearing structure for supporting the shift shift shaft should be provided. However, there is little need to improve the strength of the transmission case and the like for this purpose, and in this respect as well, a configuration in which the transmission shift shaft is supported by the transmission case and the differential case is useful.
[0007]
(Structure) The invention according to claim 2 is configured such that a transmission case is configured by interposing a space case between a transmission case and a differential case, and a transmission gear mechanism is provided in the transmission case, and the transmission of the transmission gear mechanism is provided. There the axis that is supported by said transmission case bearing wall bearing wall of the differential case, the effects thereof are as follows.
[0008]
(Effect) That is, similarly to the case of Claim 1, the space case can be reduced in weight and simplified.
[0009]
(Configuration) The invention according to claim 3 is configured such that a transmission case is configured by interposing a space case between a transmission case and a differential case, and a transmission gear mechanism is provided in the transmission case, and the transmission gear mechanism is switched. The shift shifter to be operated is slidably supported on the shift shift shaft, and both shaft ends of the shift shift shaft are supported on the bearing wall of the transmission case and the bearing wall of the differential case, and the transmission shaft of the shift gear mechanism is The operational effect is as follows, with the bearing wall of the mission case and the bearing wall of the differential case supporting the mission case .
[0010]
(Effect) That is, similarly to the case of Claims 1 and 2, the space case can be reduced in weight and simplified .
[0011]
[0012]
[0013]
(Structure) The invention according to claim 4 is that a space arm is provided with a support portion of a transmission arm shaft for driving a transmission shifter for the transmission mechanism, and the operation and effect thereof are as follows.
[0014]
(Effect) In other words, in a model having a space case, the speed change arm shaft only needs to be supported by a support portion provided in the space case. Thus, there is little need to change the operation linkage mechanism between the speed change operation tool and the speed change arm shaft, and modification by providing a space case can be minimized.
[0015]
(Structure) The invention according to claim 5 is that the support portion of the speed change arm is provided on the side close to the transmission case in the space case, and the operation and effect thereof are as follows.
[0016]
(Operation and Effect) In other words, by lapping a bearing portion provided in a space case as possible the transmission case side, not only the speed change gear mechanism provided in the space case, operations for speed change gears located in the transmission case This makes it possible to reduce restrictions on the installation position of the transmission gear mechanism.
[0017]
(Structure) The invention according to claim 6 is that the space case is provided with a receiving port for receiving the return oil of the working device, and the operation and effect thereof are as follows.
[0018]
(Effect) In other words, since the oil receiving port is provided in the space case, the receiving port is provided at the same position as when the space case is not provided, and the piping path and piping itself are remodeled. It is not necessary, and it is configured to change the number of gears of the transmission by adding a space case, but it is not necessary to change parts that are not intended to be modified, such as piping, and it is not changed by the above configuration However, it is possible to minimize the modification required for the change.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, a main clutch housing 2 is connected to the rear end of the engine 1, and a rear transmission case 3 located at the rear of the machine body and the main clutch housing 2 are connected by a hollow housing 4. Further, a front axle case 7 that pivotally supports a front steering wheel 6 is supported on the front frame 5 in a freely rolling manner, and a rear wheel 8 is pivotally supported on a rear transmission case (an example of a transmission case) 3. Agricultural tractor is provided with a driver's seat 9 at the rear of the machine body, a lift arm 10 that is moved up and down by hydraulic drive, and various working devices connected to the rear of the machine body via a three-point link mechanism (not shown). Is configured.
[0020]
Next, the internal structure of the rear transmission case 3 will be described. As shown in FIG. 2, the rear transmission case 3 includes an auxiliary transmission mechanism (an example of an auxiliary transmission unit or a transmission gear mechanism) 11, a transmission case 3 a, a differential case 3 b that pivotally supports the rear wheel 8, A space case 3c that connects the cases, and a hydrostatic continuously variable transmission (hereinafter referred to as "HST") 12 is mounted on the front surface of the mission case 3a. The HST 12 includes a variable displacement pump P and a constant displacement motor M. The HST 12 receives engine power directly on the pump shaft 13 and continuously changes speed. The pump P can change and adjust the discharge direction and discharge amount of the pressure oil to be discharged by changing the swash plate angle so that the motor shaft 14 can be continuously shifted forward and backward to perform a stepless forward / reverse shift. The swash plate angle of the pump itself is changed by a shift pedal (not shown) operated with the right foot to correspond to the forward / reverse shift described above.
[0021]
As shown in FIG. 2, the output from the motor shaft 14 is shifted in three stages on the drive shaft 15 (an example of the output side transmission shaft) of the subtransmission mechanism 11 to be the final transmission shaft (input side transmission shaft or transmission shaft). An example) reaches 16 and reaches a rear wheel drive differential mechanism 17 via a bevel pinion gear Gp integrally formed at the end thereof. The sub-transmission mechanism 11 includes a small-diameter gear (an example of a counterpart gear) G1, a medium-diameter gear G2, a large-diameter gear G3, and a spline attached to the final transmission shaft 16 integrally formed with a drive shaft (an example of an output-side transmission shaft) 15. Shift gear (an example of a clutch sleeve) sG1, and the shift gear sG1 is provided with an intermediate diameter gear portion G5 and a small diameter gear portion G6, and a maximum diameter gear G4 larger than the intermediate diameter gear portion G5 is adjacent to the shift gear sG1. It is provided. The maximum diameter gear G4 is loosely fitted to the final transmission shaft 16 and is restricted by a shaft retaining ring or the like so as not to move in the axial direction of the final transmission shaft 16. The small diameter gear G1 has a pitch reference circle diameter set to be substantially the same as the shaft diameter of the final transmission shaft 16, and the root diameter of the small gear G1 is smaller than the shaft diameter of the final transmission shaft 16. The maximum diameter gear G4 that meshes with this has a large diameter so that the cutting edge reaches the tooth bottom of the small diameter gear G1, and ensures a sufficiently large reduction ratio. The shift gear sG1 is provided with an internal gear type internal clutch gear portion G16 in addition to the medium diameter gear portion G5 and the small diameter gear portion G6, and the maximum diameter gear G4 meshes with the internal gear type internal clutch gear portion G16. A detachable external tooth type external clutch gear portion G17 is formed. With the above configuration, the shift gear sG1 is shifted, and the inner clutch gear portion G16, the medium diameter gear portion G5, and the small diameter gear portion G6 are selected as the outer clutch gear G17, the medium diameter gear G2, and the large diameter gear G3. , The final transmission shaft 16 is shifted into three stages of “low”, “medium”, and “high”. The inner clutch gear portion G16 and the outer clutch gear portion G17 described above form a meshing clutch portion.
[0022]
Here, the drive shaft 15 and the final transmission shaft 16 of the sub-transmission mechanism 11 are respectively provided with shaft support portions 18A and 19A on a bearing wall 18 formed at the front and rear middle of the transmission case 3a and a bearing wall 19 formed at the front end of the differential case 3b. And is supported over both the shaft support portion 18A and the shaft support portion 19A, and the space case 3c merely arranges the exterior. In the lower part of the space case 3c, a receiving port 50 for receiving return oil from a hydraulic working device (not shown) such as a front loader is opened in front of the machine body, and piping equipment linked to the working device such as hydraulic piping. It is an effective means by providing an opening in the space case 3c in that no modification is required. That is, in the model not provided with the space case 3c, the receiving port 50 is provided in the mission case 3a. However, by providing the space case 3c, the distance from the work device becomes substantially the same in the space case 3c. This is effective in that it is not necessary to modify the piping equipment. In the figure, numeral 27 denotes an oil take-out port for inserting a filter, which is led to a charge pump 28 attached to the front of the HST 12 via a hose 29 and is supplied to the hydraulic circuit of the HST 12 by filling.
[0023]
As shown in FIG. 7, shaft support portions 18B and 19B are formed on a bearing wall 18 formed at the front and rear middle of the transmission case 3a and a bearing wall 19 formed at the front end of the differential case 3b, respectively, and both shaft support portions 18B and shaft support portions are formed. The space shifter shaft 22 is supported over 19B, and the space case 3c is formed so as to simply arrange the exterior. 4 and 7, a shift fork (an example of a shift shifter) 21 of the shift gear sG1 is slidably supported along the shift shift shaft 22, and a shift arm shaft 23 for shifting the shift fork 21 is spaced. The left side surface of the case 3c is penetrated and supported on the side close to the mission case 3a. A shift operation arm 24 that engages with a boss portion 21a of the shift fork 21 is fixed to the inner end portion of the shift arm shaft 23, and the shift operation arm 24 is slidably brought into contact with the inner surface of the case so as to be swingable. . A shift arm 25 is externally fitted to the projecting portion of the shift arm shaft 23 and pin-connected, and the shift arm 25 is linked to a sub-shift lever 26 provided on the side of the driver's seat 9.
[0024]
As shown in FIG. 5, the shift operation arm 24 is made of a wide range of plate materials in the front and rear, and the three shift positions “low” and “medium” are positioned on an arc line centering on the axis of the shift arm shaft 23. The small diameter holes 31 are formed at a pitch corresponding to “high”, and the large diameter holes 32 are formed so as to correspond to the neutral position “N” between the small diameter holes 31. A push-in operation type switch 33 is attached to the outer wall surface of the space case 3c, and a short-axis pusher 35 slidably urged inward by the spring 34 to the case wall is attached to the case wall. A steel ball 36 that is slidably supported inside and outside and provided at the tip of the pusher 35 is disposed opposite to the small diameter hole 31 and the large diameter hole 32.
[0025]
The switch 33 is used as a safety switch that allows the engine to start only when the subtransmission mechanism 11 is in the neutral position. When the shift operation arm 24 is in any shift position, the steel ball 36 has a small diameter. by shallow rather populated into the hole 31, pushing the operation unit 33a of the switch 33 through the pusher 35, when the speed change operation arm 24 is in either the neutral position "N", steel grade 36 diameter By deeply engaging with the hole 32, the pushing operation of the operation portion 33a is released, and the operation state of the auxiliary transmission mechanism 11 is detected by the switch 33. As shown in FIGS. 4 and 5 , the spring ball mechanism 37 housed in the shift fork 21 is a mechanism that positions the auxiliary transmission mechanism 20 when shifting to three stages.
[0026]
As shown in FIG. 3, the power of the final speed change shaft 16 reaches the shift gear sG2 of the front wheel drive shaft 38 via the output gear G7 provided at the front end, and the front wheel drive shaft 38 passes through the HST 12 and protrudes forward. Thus, the front wheel 6 is transmitted to the front axle case 7 so that the front wheel 6 is driven at a speed synchronized with the rear wheel 8. The shift gear sG2 is configured to be able to be engaged and disengaged from the output gear G7 by a front-rear shift. Four-wheel drive is performed in the interlocking state shifted forward, and the rear wheel 8 is engaged in the disengagement state shifted backward. The two-wheel drive by only is performed.
[0027]
As shown in FIG. 2, the pump shaft 13 of the HST 12 protrudes into the mission case 3a, and a part of the engine power transmitted to the pump shaft 13 is branched to the PTO transmission mechanism 41 via gears G8 and G9. The PTO transmission mechanism 41 includes a small-diameter gear G10 and a large-diameter gear 11 that are integrally formed with the gear G9, an output shaft 42 that freely rotates and supports a gear G12 that is always meshed with the large-diameter gear 11, and a shift gear sG3 that is spline-mounted on the output shaft 42. And has. The output shaft 42 is driven at "low speed" by shifting the shift gear sG3 forward and directly meshing with the small-diameter gear G10, and the output shaft 42 is coaxially meshed with the gear G12 by shifting the shift gear sG3 rearward. Is driven at a high speed. The shift output is transmitted to the rear portion of the differential case 3b via the intermediate shaft 43, further decelerated by G13 and G14, and output from the rear PTO shaft 44. Further, an output case 46 having a mid PTO shaft 45 is attached to the bottom surface of the transmission case 3a, and the power that is not changed by the PTO transmission mechanism 41 is transmitted from the large-diameter gear G11 to the gear G12, and the relay gear G15 that meshes with the gear G12. And it is output to the mid PTO shaft 45 via the shift gear sG4. The mid PTO shaft 45 can be driven or stopped by shifting the shift gear sG4 and causing the relay gear G15 to engage and disengage.
[0028]
The present invention can also be implemented in the following forms.
In the above embodiment, the HST 12 is used as the main transmission, but here, the gear transmission 20 is adopted as the main transmission and the linkage with the auxiliary transmission mechanism 11 will be described. As shown in FIG. 8, the output transmission shaft 29 of the main transmission 20 as the main transmission unit and the input transmission shaft 30 of the sub-transmission mechanism 11 as the auxiliary transmission gear unit are arranged on the same axis and opposed to each other. A large-diameter gear G3 is externally fitted to the end of the output transmission shaft 29 and the end of the input transmission shaft 30 in a splined state. That is, a spline is formed at the end of the output transmission shaft 29 and the end of the input transmission shaft 30, and the large-diameter gear G3 is externally fitted over the ends where both splines are formed. Both ends are splined and the large-diameter gear G3 is also used as a coupling. The structure of the subtransmission mechanism 11 is the same as that of the above-described embodiment, and the medium-diameter gear G2 and the small-diameter gear G1 are integrally formed on the input transmission shaft 30.
[Brief description of the drawings]
1 is a side view of an agricultural tractor. FIG. 2 is a longitudinal side view showing a transmission mechanism. FIG. 3 is a longitudinal side view showing a transmission mechanism. FIG. 4 is a longitudinal front view showing a speed change operation structure of an auxiliary transmission mechanism. [Fig. 6] Front view of the shift operation arm [Fig. 6] Side view of the transmission case [Fig. 7] Side view of the shift shift fork [Fig. 8] Vertical side view of another structure of the sub-transmission mechanism
3 Transmission case 3a Mission case 3b Differential case 3c Space case 11 Transmission gear mechanism (sub transmission)
DESCRIPTION OF SYMBOLS 15 Output side transmission shaft 16 Input side transmission shaft 20 Main transmission part 21 Shifting shifter 22 Shifting shift shaft 23 Shifting arm shaft 27 Receiving port 29 Output transmission shaft 30 Input transmission shaft sG1 Clutch sleeve G4 Maximum diameter gear G16, G17 Engagement clutch

Claims (6)

A transmission case is configured by interposing a space case between the transmission case and the differential case, and a transmission gear mechanism is provided in the transmission case, and a transmission shifter for switching the transmission gear mechanism is slidable on the transmission shift shaft. supporting the shift both axial ends of the shift shaft, transmission structure of the tractor supporting the bearing walls of the bearing wall of the transmission case differential case to. Thereby constituting a transmission case with intervening space case between the transmission case and the differential case, and interior of the transmission gear mechanism in the transmission case, wherein the transmission shaft of the transmission gear mechanism and the bearing wall of the transmission case differential casing Structure of the tractor supported by the bearing wall . A transmission case is configured by interposing a space case between the transmission case and the differential case, and a transmission gear mechanism is provided in the transmission case, and a transmission shifter for switching the transmission gear mechanism is slidable on the transmission shift shaft. The transmission shift shaft is supported at both ends thereof by a bearing wall of the transmission case and a bearing wall of the differential case, and the transmission shaft of the transmission gear mechanism is supported by the bearing wall of the transmission case and the bearing of the differential case. Tractor transmission structure supported by a wall . The transmission structure for a tractor according to any one of claims 1 to 3, wherein a support portion of a transmission arm shaft that drives a transmission shifter for the transmission mechanism is formed in the space case. The transmission structure for a tractor according to claim 4 , wherein the support portion of the transmission arm shaft is provided on the side close to the transmission case in the space case. The transmission structure for a tractor according to any one of claims 1 to 5 , wherein the space case is provided with a receiving port for receiving the return oil of the working device.

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