JPH0725277B2 - Work vehicle - Google Patents

Description

Detailed Description of the Invention

[Field of Industrial Application] The present invention relates to a speed-up drive state in which the rotation speed of the front wheels is set higher than that of the rear wheels, and a standard drive state in which the rotation speeds of the front and rear wheels are set to substantially the same speed. The present invention relates to a work vehicle which is provided with a switchable front wheel transmission and which is configured to switch the front wheel transmission to a speed-up drive state when the left-right steering angle of the front wheels exceeds a set angle. (Prior Art) In this type of work vehicle, for example, when the vehicle is turned suddenly on a sloping ground, strong centrifugal force acts on the vehicle and there is a danger of tipping over. The switching mechanism associated with the pointing device must be deactivated. Therefore, in the conventional work vehicle,
As disclosed in Japanese Patent Publication No. 26, a mode selection lever for operating the switching mechanism is provided, and a mode in which the mode can be switched to the speed-up drive state of the front wheel transmission by manually operating the lever I was able to choose to.

[Problems to be Solved by the Invention]

In the work vehicle configured as described above, since the mode selection lever can be held by itself in the operated position, it is easy to neglect which of the levers is operated and the front wheel transmission is There is a risk that the aircraft may make a sharp turn on a sloping ground while in a mode in which it is possible to switch to a speed-up state, and improvement has been desired. The present invention was devised in light of such a situation, and prevents the front wheel transmission mechanism from switching to a speed-up drive state when the vehicle body makes a sharp turn on a sloping ground. The purpose is to avoid the danger caused by. [Means for Solving the Problems] A feature of the present invention is that a switching mechanism for a front wheel transmission is provided while being always biased toward a standard drive state, and a mode selection lever for operating the front wheel transmission and the switching mechanism is provided. , A holding mechanism capable of holding at a speed-up drive position against the biasing force is provided, and further, an inclination sensor for detecting the inclination of the machine body is provided, and when the inclination sensor detects the inclination of the machine body at a set angle or more, It is configured to release the holding mechanism of the mode selection lever to switch the front wheel transmission to the standard drive state, and the operation and effect thereof are as follows. [Operation] In other words, if the work vehicle is located on a sloping ground and the aircraft tilts,
If the inclination sensor detects the inclination and it is equal to or more than the set angle, the mode selection lever held in the front wheel speedup position is released and the mode selection lever is automatically returned to the standard drive state. It will be. [Effects of the Invention] Therefore, even if the front wheel transmission is selected to the mode in which the speed can be switched to the speed-increasing state when the vehicle makes a sharp turn on the sloping ground, the speed-changing drive state is not switched to. You can now safely turn. Moreover, the restraint means for preventing the front wheel speed increase from operating during rolling of the airframe includes a spring for constantly urging the switching mechanism of the front wheel transmission to the standard drive state side, and a mode selection lever against the urging force. Since the holding mechanism for holding the vehicle at the speed increasing position and the means for releasing the holding mechanism by the inclination sensor are used, the structure of the front wheel speed increasing and restraining means can be simplified. [Embodiment] As shown in FIG. 7, a pair of left and right steerable front wheels (1) are drivable, and a pair of left and right unsteered rear wheels (2) are drivable. In the rear part of the traveling machine body, a lift arm (3) that connects various working devices such as a rotary tiller and the like so that the work device can be moved up and down, and a power take-off shaft (4) that is transmitted to the connected working device are provided. An agricultural tractor, which is an example, is configured. In order to enable the steering operation of the front wheel (1), as shown in FIGS. 5 and 6, the handle (5) has a rotating shaft (6), a gear transmission mechanism (7) and a rotating shaft (8). The steering gear mechanism (9) is interlocked with the steering gear mechanism (9), and the pitman arm (11) attached to the steering mechanism (9) so as to swing around the shaft center (P ₁ ) is passed through the tie rod (12). The pair of front wheels (1) are interlocked with the knuckle arms (13) of the pair of front wheels (1), and the operating force is transmitted by rotating the handle (5) so that the pair of front wheels (1) has their respective axial cores. (P ₂ ) A pair of front wheels (1) swinging around
And the handle (5) are interlocked. A mission case (14) forming the rear part of the traveling body
A transmission (15) for the front wheel (1) is provided at the front end of the transmission (15), and the transmission (15) is constructed as shown in FIGS. 1 and 4. That is, a standard speed transmission gear (18) with a clutch pawl portion (18a) that interlocks with a front output gear (16) of a transmission (not shown) via a gear (17), and the gear (17). Speed-increasing transmission gear (22) with multi-plate friction clutch (21) that is interlocked with the rotary shaft (19) and gear (20)
And are attached to the output shaft (23) so as to be rotatable relative to each other, and a transmission member (25) that is integrally rotatable and slidable is attached to a sleeve (24) fitted to the output shaft (23) by spline fitting. Then, a shifter (26) for slidingly operating the speed change member (25) is slidably attached to the mission case (14) via a support shaft (27), and the shifter (26) is first operated. When operated to the position (S), the gear shift portion (25) can be engaged with and disengaged from the clutch pawl portion (18a).
via a) is engaged with the standard speed transmission gear (18) so as to be integrally rotatable, and the average peripheral speed of the pair of front wheels (1) and the average peripheral speed of the pair of rear wheels (2) are the same or substantially the same. When the shifter (26) is moved to the second operating position (N) in the standard four-wheel drive state in which power is transmitted to the front wheel differential mechanism (28) as described above, the speed change member (25) causes the standard speed transmission gear ( 18) and the friction clutch (21) is brought into a non-pressing state while only the pair of rear wheels (2) are driven so that the pair of front wheels (1) is in an idling state. It becomes a two-wheel drive state that cuts off the transmission to 1), and the shifter (26)
Is operated to the third operation position (H), the speed change member (25) enters the friction clutch (21) by the operation portion (25b) and operates to rotate integrally with the speed increasing transmission gear (22). In order to make the average peripheral speed of the front wheel (1) higher than the average peripheral speed of the pair of rear wheels (2), the speed increasing drive state is transmitted to the front wheel differential mechanism (28). In other words, the sliding operation of the speed change member (25) interlocked with the operation of the shifter (26) switches the two-wheel drive state to the above-mentioned three states. It is possible to interlock with the shifter (26) via a swing arm (29) having a free end engaged with the shifter (26) and a rotary cylinder shaft (30) penetrating the transmission case (14), ,
The interlocking tool (31) attached to the portion of the rotary cylinder shaft (30) located outside the mission case (14) by spline engagement so as to be integrally rotatable, and the mission case (14)
As shown in FIG. 2, a spring (33) is mounted over the bolt (32) screwed to the spring (33), and the spring (33) biases the shifter (26) to the first operating position (S). Then, the swing arm (29) and the rotary cylinder shaft (3
0), the interlocking device (31), the rotary cylinder shaft (30) rotatably passing through the transmission case (14), and the interlocking part (34a) interlocking with the interlocking device (31). The rotary shaft (34), the swing arm (36), and the release wire (positioned with respect to the mission case (14) by the contact with the tool (31) and the contact of the plastic collar (35) with the mission case (14) ( 37), interlocking rod (38), a spring (39), axial to the front wheel mounting frame of the traveling machine body (40) (P ₃₎ swing arm which is mounted so as to swing around (41) and the cam Each of the mechanisms (42) constitutes an interlocking mechanism (43) of the shifter (26) and the pitman arm (11) as an interlocking member of the front wheel (1) and the handle (5). The cam mechanism (42),
As shown in FIG. 5, a cam groove (45) formed by a cam plate (44) bolted to the pitman arm (11).
And a roller (47) fitted in the cam groove (45) in a state of being attached to the swing arm (41) via a support shaft (46) so as to swing integrally, As shown by the solid line in the figure, when the pitman arm (11) is in the set swing range (L) with the neutral position (A) where the front wheel (1) goes straight, as an intermediate point, the cam groove Inner part of (45) (45
a) acting on the roller (47) and the spring (3
By the action of 3), the swing arm (41) is positioned at the first mounting position (R) and the shifter (26) is positioned at the first operating position (S). As shown in phantom in FIG. 5, when the pitman arm (11) swings to the left or right side of the machine beyond the set swing range (L), the outer portion (45b) of the cam groove (45) or (45
c) acts on the roller (47), and the pitman arm (11)
The swinging arm (41) is attached to the second mounting position (F) by the swinging force.
The shifter (26) is switched to the third operation position (H) by swinging the switch. That is,
When the steering angle of the front wheel (1) is less than the set value, the transmission (15) is in the standard four-wheel drive state, and when the front wheel (1) is steered above the set value. The transmission (15) is automatically switched to the speed increasing drive state. The interlocking device (31) is slid for spline engagement with the rotary cylinder shaft (30) located on the shifter (26) side from the interlocking device (31), and the interlocking device (31) is slid along with the sliding. The joint portion (34a) is configured to be integrally rotatably engaged with or relatively rotatably disengaged from. Then, as shown in FIG. 1 and FIG. 3, the first shaft core (P ₄ ) is attached to the mission case (14) through the support shaft (48) and the fixture (49).
And the interlocking tool operating member (50) is mounted so as to swing around each of the second shaft core (P ₅ ), and the mission case is mounted around the first shaft core (P ₄ ) together with the mounting fixture (49). The operating lever (51) is slidably inserted into a tubular body (52) that is continuously provided so as to swing with respect to (14), and the operating arm portion (of the interlocking tool operating member (50) ( This operation lever (51) is connected to the pin (50a) so that it can swing relative to each other, and the transmission (15) and the transmission (15) can be moved by the rotation and sliding operation of the interlocking device (31) by the manual operation of the operation lever (51). The interlocking mechanism (4
An operating mechanism for switching 3) is configured. That is, the guide (54) for the operation lever (51) is operated along the vertical groove portion (55a) of the guide groove (55) formed so as to act on the projection (51a) of the operation lever (51). As the lever (51) is moved up and down, the interlocking tool operating member (50) swings around the second axis (P ₅ ) and the interlocking tool (31).
So as to slide the rotary cylinder shaft (30), and
As the operating lever (51) is operated along the lateral groove portion (55b) of the guide groove (55), the interlocking tool operating member (50)
Swings around the first axis (P ₄ ) to press and rotate the interlocking tool (31), or the interlocking tool (31) moves to the spring (33).
It is allowed to be rotated by. More specifically, when the operation lever (51) is operated to the first operation position (4WD I), the interlocking device (3
1) is engaged with the rotary shaft (34) to bring the interlocking mechanism (43) into an interlocking state, and the interlocking tool operating member (50) is located at a position where the shift operation of the shifter (26) by the pitman arm (11) is allowed. ) Oscillates, and the transmission (15) enters a front wheel speed-increasing four-wheel drive mode in which the pitman arm (11) can switch between the standard four-wheel drive state and the speed-increasing drive state. Then move the operating lever (51) to the second operating position (4WD
When operated to (II), the interlocking device (31) is disengaged from the rotary shaft (34) and the interlocking mechanism (43) becomes non-interlocking state, and the shifter (26) is moved by the spring (33) to the first operating position. The transmission (15) enters the standard four-wheel drive mode in which the transmission (15) is maintained in the standard four-wheel drive state. Then, when the operation lever (51) is operated to the third operation position (2WD), the interlocking tool (31) is disengaged from the rotary shaft (34), and the interlocking mechanism (43) is brought into the non-interlocking state, and
The interlocking tool operating member (50) swings to a position where the interlocking tool (31) is pressed against the spring (33) so that the shifter (26) comes to the second operating position (N), and the operating lever is moved. (Five
By the action of the spring plate (56) that releasably holds 1) in the third operation position (2WD), the shifter (26) receives the interlocking device (31) so as to maintain the second operation position (N). The interlocking device operating member (50) swings in the locked state of stopping and supporting, and the transmission (15) enters the two-wheel drive mode in which the two-wheel drive state is maintained. The operation cover (61) containing the interlocking device (31) is internally provided with a spring (69) for urging the interlocking device (31) in a direction to separate from the rotating shaft (34). Equipment (1
5) is maintained in the standard four-wheel drive state and the operation lever (51) is biased downward. The operation lever (51) is provided with a front wheel speed increasing / decreasing means (62). Specifically, the contact portion (63) is provided in the vicinity of the protrusion (51a) of the operation lever (51), while the latch (6) is attached to the fender (64) to which the cover (54) is fixed.
5) is provided, and the latch (65) is urged toward the operation lever (51) side. When the operating lever (51) is moved up, the abutment part (63) is tapped on the lower surface (65a) of the latch (65).
To the first operation position (4WD
I) is allowed to operate, and the first operation position (4
When operated to WD I), the contact part (63) contacts the upper surface of the latch (65) to move from the first operating position (4WD I) to the second operating position (4WD).
The operation to (II) is regulated. Premium (6
The plunger (66) of the solenoid (SL) provided on the fender (64) side is connected to 5), and the latch (65) is actuated by operating this solenoid (SL) in the first drive state. It is pulled back and the operating lever (51) is automatically operated from the first operating position (4WD I) to the second operating position (4WD II) to switch to the standard four-wheel drive mode. The solenoid (SL) is energized when the switch (SW) provided in the driver (67) is turned on, or when the tilt sensor (68) provided behind the driver (67) has a set angle or more. It is designed to be performed only when the front and rear and left and right tilts of the aircraft are detected. In other words, the front wheel speed-increasing restraint means (62) is for preventing the front wheel speed-increasing four-wheel drive mode when the vehicle is turning on a sloping ground, and for preventing a sudden centrifugal force from acting on the vehicle. is there. The bolt (32) is engaged with the rotary cylinder shaft (30) so as to suppress sliding of the rotary cylinder shaft (30) with respect to the transmission case (14), and a stopper (57) as shown in FIG. Is fixed to the mission case (14) in cooperation with the lock nut (58). Further, a head portion of the bolt (32) is provided with a stopper portion for the interlocking tool operating member (50), and the stopper portion is operated to bring the shifter (26) to the second operating position (N). The bolt (32) is arranged so as to contact the interlocking member operating member (50) and position the shifter (26) at the second operating position (N). In the above embodiment, the interlocking device (31) provided in the interlocking mechanism (43) is referred to as a switching mechanism of the front wheel transmission (15),
The contact portion (63) and the latch (65) provided in the front wheel speed increasing / decreasing control means (62) are collectively referred to as a holding mechanism for holding the lever in the speed increasing position. Further, the front wheel speed increasing and restraining means (62) described in the present embodiment is applied to the agricultural tractor configured as described above. Therefore, the solenoid (SL) may be connected to the operation lever (51) so that the operation lever (51) is forcibly pulled to the lower second operation position (4WD II) by energization. In addition, a hydraulic front wheel speed increasing clutch and a standard drive clutch are installed in the transmission (15), an electromagnetic valve for selectively turning on and off these clutches is provided, and operation of the front wheel vehicle (1) is performed. In the case of an agricultural tractor that is equipped with a steering angle sensor that electrically detects the steering angle and operates the electromagnetic valve control device based on the detection signal sent from this sensor, the tilt sensor When the control device ignores the detection signal from the steering angle sensor when the control signal is received, it is possible to replace the front wheel speed-increasing and restraining means with electrical processing. Further, the tilt sensor (68) may be configured to detect only the tilt in the front-rear direction or the left-right direction of the body. It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show an embodiment of a work vehicle according to the present invention. Fig. 1 is a vertical sectional front view showing an operating structure of a front wheel speed increasing device and a front wheel speed increasing and restraining means, and Fig. 2 is a sectional view taken along line II-II of Fig. 1. Figures and 3 are the first
Fig. 3 is a sectional view taken along the line III-III, Fig. 4 is a sectional view taken along the line IV-IV in Fig. 5, Fig. 5 is a plan view showing the operating structure of the front wheels, Fig. 6 is a side view of the same, and Fig. 7 is the whole. It is a side view. (1) …… front wheel, (2) …… rear wheel, (15) …… front wheel transmission, (31) …… switching mechanism, (63), (65) …… holding mechanism, (68) …… tilt sensor.

Claims (1)

[Claims] 1. A speed-up drive state in which the rotational speed of the front wheels (1) is set higher than the rotational speed of the rear wheels (2) and the rotational speeds of the front and rear wheels (1), (2) are substantially the same. A front wheel transmission (15) capable of switching to a standard drive state set to is set, and when the left-right steering angle of the front wheel (1) becomes equal to or greater than a set angle, the front wheel transmission (15) is switched to a speed-up drive state. In the work vehicle configured as described above, the switching mechanism (31) of the front wheel transmission (15) is always biased toward the standard drive state, and the switching mechanism (3) of the front wheel transmission (15) is provided.
A holding mechanism (63) capable of holding the mode selection lever (51) for operating 1) at the speed-up drive position against the biasing force.
(65) is provided, and an inclination sensor (68) for detecting the inclination of the body is further provided, and the inclination sensor (68) is also provided.
Detects the tilt of the aircraft over a set angle, the holding mechanism (63), (65) of the mode selection lever (51) is released to switch the front wheel transmission (15) to the standard drive state. A working vehicle.