JP2721184B2 - Shifting structure of work vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a shift structure of a working vehicle used for, for example, a front wheel transmission and the like, and more specifically, a pair of axially spaced output shafts provided on an output shaft. A normal speed transmission normal biting gear and a standard speed transmission normal biting gear that always mesh with each of the transmission gears are provided on the same transmission shaft so as to be spaced apart in the axial direction, and the double speed transmission on the transmission shaft is provided. Between the transmission normal biting gear and the standard speed transmission normal biting gear, the clutch case is provided via a clutch case having a built-in piston and a transmission friction multi-plate clutch which is brought into a contact transmission state by pressing the piston. The present invention relates to a shift operation structure of a working vehicle, which includes a spring that supports a clutch body capable of transmitting power to the piston and biases the piston in a non-pressed state.

[Conventional technology]

As a shift operation structure of this type of work vehicle, there has been proposed a structure in which two kinds of speed states are selectively switched and provided for transmission to a transmission shaft. As disclosed in Japanese Patent Application Laid-Open No. 60-76475, a clutch for switching between a speed-up transmission mechanism and a transmission shaft so as to be able to transmit, and a switch for switching between a standard speed transmission mechanism and a transmission shaft so as to be able to transmit. There is known a clutch in which a piston is hydraulically driven.

[Problems to be solved by the invention]

However, in the above-mentioned conventional structure, since two sets of clutches whose pistons are hydraulically driven are provided, an expensive hydraulic clutch is provided, and control is performed such that switching of the hydraulic clutch can be performed with good timing. Since a separate mechanism must be provided, the structure is complicated and the cost is increased.

In order to solve this problem, for example,
As disclosed in Japanese Patent Publication No. 0233, there has been proposed a clutch in which an inexpensive occlusal clutch is used as a clutch for switching between a standard speed transmission mechanism and a transmission shaft so that transmission is possible.

However, in this structure, the pin integrated with the piston is configured to be removably fitted into the hole of the normal speed transmission normal biting gear. However, there is a problem that it is difficult to transmit a high torque while having only the strength corresponding to the wall thickness.

SUMMARY OF THE INVENTION An object of the present invention is to provide a shift operation structure of a working vehicle that can switch between two shift transmissions by operating a piston, has a simple structure, can be configured at low cost, and can transmit high torque satisfactorily.

[Means for Solving the Problems] In order to achieve the above object, a shift operation structure of a working vehicle according to the present invention always has a pair of transmission gears provided on an output shaft that are axially separated from each other. A normal biting gear for double-speed transmission and a normal biting gear for standard speed transmission that are engaged with each other are provided on the same transmission shaft so as to be spaced apart in the axial direction, and the double-speed transmission normal biting gear and the standard speed on the transmission shaft are provided. Between the transmission normal biting gear, a clutch case containing a piston, and a clutch body that can be transmitted to the clutch case via a transmission friction multi-plate clutch that is brought into a contact transmission state by pressing the piston. A shift operation structure of a working vehicle provided with a spring that supports and biases the piston to a non-pressed state, wherein the shift operation structure is configured to freely engage and disengage with the standard speed transmission normal bite gear. A shift member is provided to form an occlusal clutch, and the shift member located outside the clutch case, and the piston provided inside the clutch case,
The standard speed transmission normal biting gear is engaged with the shift member in the standard speed transmission normal biting gear, and the standard speed transmission normal biting gear and the output shaft side transmission gear are connected to each other. The clutch member protrudes toward the clutch case side from the bite portion, and the engaging portion of the shift member, the sliding portion of the shift member with respect to the transmission shaft, and the fitting portion of the clutch case with the transmission shaft in the clutch case are transmitted. It is configured to be located overlapping in the axis direction of the shaft,
The position of the standard bite transmission normal biting gear biting with the shift member is set closer to the normal biting portion in the radial direction than the fitting portion of the shift member with respect to the fitting portion. It has a characteristic configuration.

 The operation and effect of this characteristic configuration are as follows.

[Action]

That is, by making the friction multi-plate of the friction multi-plate clutch into a contact transmission state by pressing with the piston, one speed transmission system capable of transmitting power to the double-speed transmission normal bite gear via the transmission shaft is constituted. In addition, another speed change transmission system which is in a transmission state by the engagement of the bite clutch in conjunction with the piston is configured to be able to transmit power to the normal speed transmission normal bite gear via the transmission shaft. In addition, the occlusal clutch can be turned on and off in conjunction with the movement of the piston that presses the friction multi-plate of the friction multi-plate clutch. Further, the bite portion on the side of the standard speed transmission normal biting gear that meshes with the shift member integrally engaged with the piston in the bite clutch is formed so as to protrude outward from the thickness of the standard speed transmission normal biting gear. By doing so, the engaging portion itself becomes a reinforcement structure of the gear, and the engaging portion of the shift member and the sliding portion of the shift member with respect to the transmission shaft overlap with each other in the axial direction of the transmission shaft. Is configured to
In the occlusal state, even if an external force acts on the normal bite gear for standard speed transmission in the radial direction, the shift member receives the radial stress received by the occlusal portion directly along the radial direction by the sliding portion of the shift member. Therefore, it is difficult for the normal bite gear for normal speed transmission to be twisted. In addition, the fitting part of the clutch case to the transmission shaft is also located at a position overlapping the engaging portion of the shift member and the sliding portion of the shift member with respect to the transmission shaft in the axial direction, so that the clutch case The sum of the lengths of the transmission shaft and the normal bite transmission normal biting gear can be shortened in the axial direction by the length of the overlapping portion. Furthermore, the position of the standard bite transmission normal biting gear with the shift member is set closer to the normal biting portion in the radial direction than the position of the fitting portion of the shift member with respect to the fitting portion of the clutch case. Therefore, the stress acting on the occlusal portion during power transmission can be made relatively small.

〔The invention's effect〕

Therefore, between the normal biting gear for double speed transmission supported on the same transmission shaft and the normal biting gear for standard speed transmission, a friction multi-plate clutch and an occlusal clutch are arranged, and the on / off of these clutches is performed. The clutch can be selectively performed depending on whether or not the piston is pressed against the friction multi-plate clutch, and by engaging the shift member integrally with the piston against the occlusal clutch. The operating part can be operated by a common piston, which reduces the number of parts and eliminates the need for a mechanism to set the timing for selectively switching the transmission system. Since the configuration can be made by utilizing the above, the cost can be reduced as a whole.

In addition, in the normal bite gear for standard speed transmission, the occlusal position with the shift member forms a protruding structure with respect to the standard bite gear for standard speed transmission, so that the gear is reinforced, and in the state of bite, Even if an external force acts on the normal speed transmission normal biting gear in the radial direction, the shift member receives the radial stress received by the biting portion directly along the radial direction at the sliding portion of the shift member. The normal bite gear for standard speed transmission is hardly twisted, and the bite portion is set near the normal bite portion of the standard bite gear for normal speed transmission in the radial direction, and torque is transmitted. And the stress acting on the occlusal portion can be made relatively small, and a highly durable standard speed transmission normal bite gear that can sufficiently cope with high torque transmission can be obtained.

Further, the fitting portion of the clutch case to the transmission shaft is also located at a position overlapping the engaging portion of the shift member and the sliding portion of the shift member with respect to the transmission shaft in the axial center direction. Since the total length of the transmission shaft and the normal bite gear for normal speed transmission can be shortened in the axial direction by the length of the overlapping portion, there is an advantage that the speed change operation structure can be made compact.

〔Example〕

Hereinafter, a shift operation structure of a hydraulic work vehicle used for an agricultural tractor will be described with reference to the drawings.

As shown in FIG. 2, an engine (3) is provided at the front of the aircraft supported by the front wheels (1) and the rear wheels (2), a control unit (4) is provided at the center of the aircraft, and a transmission case (5) is provided at the rear of the aircraft. The four-wheel-drive agricultural tractor is arranged to constitute the tractor.

Next, the transmission case (5) will be described in detail with reference to FIG. 1 and FIG.
Front case (5a), and a middle case (5, HST) containing a hydrostatic continuously variable transmission (7).
b) A transmission case (5) is formed by sequentially connecting a rear case (5c) containing a gear type auxiliary transmission and a differential mechanism (not shown) from the front of the fuselage.

The power from the engine (3) is transmitted to the HST hydraulic pump via the first transmission shaft (11), and is transmitted from the HST hydraulic motor to the auxiliary transmission in the rear case (5c) to perform a gear shift operation to change the rear wheels. It is transmitted to (2).

Then, the power branched from the auxiliary transmission transmits from the rear case (5c) through the middle case (5b) to the front case (5a).
Power is transmitted to the front wheel transmission (6) via the second transmission shaft (14) inserted therein. As shown in FIG. 1, the front wheel transmission (6) includes a friction multi-plate hydraulic clutch (15), a gear occlusion type occlusion clutch (16), and a frictional multi-plate hydraulic clutch (15) mounted on a first transmission shaft (9) as a transmission shaft. A shift member (17) or the like for selectively engaging and operating both clutches (15) and (16). In a straight running state, the occlusal clutch (16) is engaged and the second transmission shaft (14) is engaged. Is transmitted to a third transmission shaft (19) via a gear rotatably supported on an output shaft (18) to the front wheel (1) and a gear meshing with the gear, and the third transmission Via the shaft (19), the front wheel (1) and the rear wheel (2) are transmitted to the front wheel (1) while being driven at substantially the same speed.
When the steering handle (20) is steered beyond the set angle, the shift member (17) slides from the engagement side of the bite clutch (16) to the engagement side of the hydraulic clutch (15) (rightward in FIG. 1) by hydraulic pressure. Operated clutch case (1
2) and the clutch body (13) can be transmitted through the friction plates. Thereby, the front wheel (1) becomes the rear wheel (2).
The power is transmitted with the speed increased.

The clutch body (13) will be described in detail with reference to FIG.
And a double-speed transmission normal biting gear (21) is freely rotatably supported on the first transmission shaft (9), and is always meshed with the double-speed transmission normal biting gear (21). The small diameter gear (23) is provided integrally with the output shaft (18). On the other hand, a standard bite transmission normal bite gear (22) for transmitting at a standard speed is slidably supported on the first transmission shaft (9) so as to double as a member constituting the bite clutch (16). With this standard speed transmission normal bite gear (2
A large-diameter gear (24) as a transmission gear which is always meshed with 2), that is, always bites, is provided integrally with the output shaft (18). A piston (11) integrally connected to the shift member (17) is inserted into the clutch case (12) so as to press the friction multi-plate,
A spring (10) is provided for urging the piston (11) to a non-pressed state for separating the piston (11) from the multiple friction plates. The spring (10) is of a compression type. One end of the spring (10) is supported by the piston (11), and the other end is supported by a stopper (8) provided on the first transmission shaft (9). I have. The piston (11) is linked to the shift member (17) via a link member. As described above, the structure in which one end of the spring (10) is supported by the first transmission shaft (9) enables simplification of the structure of the clutch case (12) and the like. In addition, bite clutch (16)
As shown in FIG. 1, the normal bite gear (22) of the standard speed transmission normal biting gear (22), which meshes with the shift member (17), And the occlusal part (22a)
Is close to the large-diameter gear (24) of the normal speed transmission normal biting gear (22) and the tooth part that normally bites, that is, the fitting position of the standard speed transmission normal biting gear (22) to the transmission shaft (9). It is set to be located closer to the outer periphery. Furthermore, shift member (17)
In FIG. 1, as shown in FIG. 1, a bite portion (17a) that bites with a bite portion (22a) of the normal bite gear for normal speed transmission (22).
A sliding portion (17b) that slides through a boss portion (12a) as a fitting portion of the clutch case (12) to the transmission shaft (9);
The transmission shaft (9) overlaps in the axial direction of the transmission shaft (9).
The shift member (17) is configured so that the range of engagement with the shift member (a) and the sliding range of the shift member (17) with the boss (12a) of the clutch case (12) overlap.

[Alternative Embodiment] The shift operation structure of the work vehicle has been described as a hydraulic type, but a dry friction multiple disc clutch that operates the piston (11) by manual operation other than hydraulic pressure may be used.

The spring (10) may be a disc spring or the like other than the coil spring, and is not limited to the above.

The stopper (8) may be formed integrally with the first transmission shaft (9) or may not be provided separately.

The above embodiment may be used for other agricultural machines other than agricultural tractors or other work vehicles.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the structure shown in the attached drawings.

[Brief description of the drawings]

The drawings show an embodiment of a shift operation structure of a work vehicle according to the present invention. FIG. 1 is a longitudinal side view of a clutch used for a front wheel transmission, and FIG. 2 is a side view of an agricultural tractor. (9) ... transmission shaft, (10) ... spring, (11) ...
Piston, (12) Clutch case, (12a) Fitting part, (13) Clutch body, (15) Multi-plate friction clutch, (16) Occlusal clutch, (17) ... Shift member, (21) ... Double-speed transmission normal biting gear, (22) ...
… Normal bite gear for standard speed transmission, (23), (24)… Transmission gear, (17a)… Occlusion part, (17b)… Sliding part, (22a)
.... Occlusal part.

Claims (1)

(57) [Claims] 1. A double-speed transmission normal biting gear (21) which constantly meshes with each of a pair of transmission gears (23) and (24) provided on an output shaft (18) so as to be spaced apart in the axial direction, and a standard speed. A transmission normal biting gear (22) is provided on the same transmission shaft (9) so as to be spaced apart in the axial direction, and the double-speed transmission normal biting gear (21) on the transmission shaft (9) is standardized. A clutch case (12) containing a piston (11) between the normal transmission bite gear (22) for speed transmission, and a transmission friction multi-plate clutch ( 15) and a clutch body (13) that can be transmitted to the clutch case (12) through the clutch (12).
A shift operation structure of a working vehicle provided with a spring (10) for urging the non-pressed state to a non-pressed state, wherein the shift member is capable of shifting to engage and disengage the normal bite gear (22) for normal speed transmission. (17) to form an occlusal clutch (16), the shift member (17) located outside the clutch case (12), and the clutch case (12).
The piston (11) provided inside the clutch member (12) is integrally and interlockingly connected to the piston (11) so as to penetrate the clutch case (12), and the shift member (17) in the normal speed transmission normal bite gear (22). The normal biting gear (22) for standard speed transmission and the transmission gear (24) on the output shaft (18) side
And protrudes toward the clutch case (12) from the occlusal point of the shift member (17).
a) and a sliding portion (17b) of the shift member (17) with respect to the transmission shaft (9) and a fitting portion (12a) of the clutch case (12) with the transmission shaft (9). The standard speed transmission normal biting gear (22) is configured to overlap with the shift member (17) in the axial direction of the shaft (9). A shift operation structure of a working vehicle, which is set in a position radially outward of a portion where the shift member (17) engages with the shift member (17) with respect to the normal bite portion.