JP2513763Y2 - Front wheel speed increasing device for four-wheel drive vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a front wheel speed increasing device for a four-wheel drive vehicle.

2. Description of the Related Art Conventionally, some front wheel drive systems of four-wheel drive vehicles include a high / low speed switching device using a one-way clutch. This high / low speed switching device is composed of a low speed side gear connected to the front wheel power take-off shaft via a one-way clutch and a high speed side gear removably connected to the front wheel power take-out shaft via an electromagnetic clutch. There is. A lock slide gear that locks the operation of the one-way clutch by meshing with the low speed gear is slidably spline-fitted to the front wheel power output shaft. The high / low speed switching device and the lock slide gear are housed in the front wheel power take-out case.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Since the high / low speed switching device uses an electromagnetic clutch, the high / low speed switching device becomes large, and therefore the front wheel power take-out case cannot be downsized. Further, since the lubricating oil for lubricating the gear exists in the front wheel power take-out case, it is difficult to secure the sealing property when the electric wiring for operating the electromagnetic clutch is performed. Further, since the electromagnetic clutch transmits driving force by frictional force, it is difficult to transmit high torque.

Means for Solving the Problems In a four-wheel drive vehicle in which a rear wheel and a front wheel connected to a front wheel power take-off shaft are respectively driven, a low speed side gear attached to the front wheel power take-out shaft via a one-way clutch and the above-mentioned A high speed side gear rotatably mounted on the front wheel power takeoff shaft and a claw that is slidably fitted to the front wheel power takeoff shaft and engages with the high speed side gear detachably in response to the steering operation of the steering device. A high / low speed switching device having a clutch body is provided in the front wheel power take-out case, a drive unit for sliding the pawl clutch body is provided outside the front wheel power take-out case, and a rotatable unit connected to the claw clutch body. The shift arm and the first link connected to the drive unit are arranged substantially in parallel, and the shift arm and the first link are rotatably connected via the second link. In addition, the shift arm and the second link are set to be substantially at a right angle when the claw clutch body and the high-speed side gear are engaged by the operation of the drive unit.

Action When the four-wheel drive vehicle is straight ahead, the drive unit does not operate, and the drive force is transmitted to the front wheel power take-off shaft from the low-speed gear through the one-way clutch, while the steering device is steered. When the drive unit operates in response to an operation, the pawl clutch body is slid by the operation of the drive unit and meshes with the high-speed side gear to drive the front wheel power take-out shaft via the high-speed side gear and the pawl clutch body. Force transmission takes place,
The peripheral speed of the front wheels increases.

Further, when the drive unit is operating, the shift arm is rotated via the first link and the second link, and the pawl clutch body slides with the rotation of the shift arm and meshes with the high speed side gear. . Then, when the drive unit is operating, the shift arm and the second link are substantially perpendicular to each other.

An embodiment of the present invention will be described with reference to the drawings. First,
An engine 2, a clutch case 3, a transmission case 4, and a differential case 5 are arranged in this order from the front on the abdomen of the tractor 1 which is a four-wheel drive vehicle, and a front wheel power take-out case 6 is fixed to the lower portion of the differential case 5. . A main clutch 7 is housed in the clutch case 3, and a forward / reverse switching device 8 and a main transmission 9 are installed in the transmission case 4.
And a sub transmission 10 are housed, and a creep device 11, a front wheel power take-off device 12, and a rear wheel differential device 13 are housed in the differential case 5.
And a PTO transmission 14, and a front wheel transmission 15 and a low speed gear 16 which are high / low speed switching devices are stored in the front wheel power take-out case 6.

Further, the drive pinion shaft 17 is provided in the differential case 5.
Is supported, and the drive pinion shaft 17 is fixed to one end of the drive pinion shaft 17.
The other end of 17 is connected to the creep device 11. Further, the drive pinion 18 meshes with a bevel gear 19 of the rear wheel differential gear 13, and a rear wheel 21 is connected to the rear wheel differential gear 13 via a final reduction gear 20. A rear wheel steering mechanism (not shown) including a tie rod and a knuckle arm is connected to the rear wheel 21, and a steering device (not shown) including a steering wheel is connected to the rear wheel steering mechanism. Has been done.

A front wheel power take-off shaft 22 is rotatably supported in the front wheel power take-out case 6, and a bearing sleeve 23 is attached to the front wheel power take-out shaft 22.
The claw clutch body 24 is spline-fitted, and the claw clutch body 24 is slidably provided.
A low speed side gear 27 is held on the outer peripheral portion of the bearing sleeve 23 via bearings 25 and 26, and a high speed side gear 29 is held via a bearing 28.
The low speed gear 16 is spline-fitted to 22.
A one-way clutch 30 that transmits a driving force from the low speed gear 27 to the bearing sleeve 23 only in one direction is interposed between the low speed gear 27 and the bearing sleeve 23. Further, a claw portion 31 is formed on the side surface of the high speed side gear 29, and the high speed side gear 29 and the front wheel power take-off shaft 22 are connected by the engagement of the claw portion 31 and the claw clutch body 24. ing. The low speed side gear 27, the high speed side gear 29, the one-way clutch 30, the pawl clutch body 24 and the like constitute the front wheel transmission device 15.

The front wheel power take-out case 6 is provided in the differential case 5.
A pair of front and rear support portions 32, 33 integrally formed with the support portion 32, 33 extend, and the support shaft 34 is held by these support portions 32, 33. A first intermediate gear 35 and a second intermediate gear 36 are axially supported by the support shaft 34, and the first intermediate gear 35 has a low-speed gear portion 37 and a low-speed gear portion 37 that always mesh with the low-speed gear 27. A high speed side gear 29 and a high speed gear portion 38 that constantly meshes are formed. Further, the second intermediate gear 36 always meshes with the low speed gear 16. A front wheel power take-out gear 39 that selectively meshes with the low speed gear portion 37 and the second intermediate gear 36 is slidably spline-fitted to the drive pinion shaft 17. And these intermediate gears 35,3
The front wheel power take-out device 12 is constituted by the front wheel power take-out gear 39 and the like.

The front wheel power takeoff shaft 22 is connected to one end of a front wheel power transmission shaft 41 covered by a transmission shaft cover 40,
The other end of 41 is connected to a front wheel differential device 42, and further front wheels 44 are connected to the front wheel differential device 42 via a final reduction gear 43. A front wheel steering mechanism (not shown) including a tie rod and a knuckle arm is connected to the front wheels, and the steering device (not shown) is connected to the front wheel steering mechanism. Here, when the driving force is transmitted to the front wheels 44 via the low speed side gear 27 or the low speed gear 16, the peripheral speeds of the front wheels 44 and the rear wheels 21 are set to be substantially equal to each other. On the other hand, when the driving force is being transmitted to the front wheels 44 via the high-speed gear 29, the front wheels 44
The peripheral speed of the front wheels 44 increases so that the turning radii of the rear wheels 21 and the rear wheels 21 become substantially equal to each other.

Here, the pawl clutch body 24 is the front wheel power output shaft 22.
The claw clutch body 24 is fitted with a spline so as to be slidable upward, and a ring-shaped groove 45 is formed on the outer peripheral portion of the pawl clutch body 24. On the other hand, a support shaft 46 is rotatably supported in the front wheel power take-out case 6, and a shifter fork 47 engaged with the groove 45 is fixed to the support shaft 46 by a locking pin 48. ing. One end of the support shaft 46 has the front wheel power take-off case 6
One end of a shift arm 49 is fixed to the tip end portion of the support shaft 46 protruding outside the front wheel power take-out case 6.

Next, an electromagnetic solenoid 50, which is a drive unit for sliding the pawl clutch body 24, is provided outside the front wheel power take-out case 6, and the electromagnetic solenoid 50 is arranged substantially parallel to the shift arm 49. First Link 51
One end of the pin is rotatably connected by a pin 52. A second link 53 is rotatably connected by pins 54 and 55 between the other end of the first link 51 and the other end of the shift arm 49. Further, a third link 57, one end of which is rotatably attached to the fixed pin 56, is provided, and the other end of the third link 57 is connected to the links 51, 53 by the pin 54.
Is rotatably connected to. Further, the third link 57 is provided with a return spring 58 for applying a force in the direction opposite to the operation direction of the electromagnetic solenoid 50. When the electromagnetic solenoid 50 is in operation, as shown in FIG. 5, the second link 53 is substantially perpendicular to the shift arm 49 and the first link 51, and the second link 53 and The third link 57 and the third link 57 are configured to be substantially linear.

As shown in FIG. 7, the electromagnetic solenoid 50 includes a turning detection switch 59 that detects the steering operation of the steering device in the vicinity of the maximum steering angle and closes the steering device, and the auxiliary transmission device 10 operates at high speed. An auxiliary shift detection switch 60 that closes when operated to a shift position other than the shift state, and a creep detection switch that is connected in parallel to the auxiliary shift detection switch 60 and that closes when the creep device 11 is in the creep state. 61, a forward detection switch 62 that closes when the forward-reverse switching device 8 is in the forward drive state, and a front-wheel automatic shift change switch that closes when the front-wheel power take-out gear 39 meshes with the low-speed gear portion 37 to drive the front wheel 44. It is electrically connected to the battery 64 via the switch 63.

In such a configuration, first, the driving force from the engine 2 is transmitted from the main clutch 7 to the forward / reverse switching device 8, and the forward / reverse switching device 8 causes the main transmission device 9 and the auxiliary transmission device.
It is transmitted to the drive pinion shaft 17 via 10 and the creep device 11, and further transmitted to the rear wheel 21 via the rear wheel actuating device 13 and the final reduction gear device 20, and the rear wheel 21 is rotationally driven.

Further, when the front wheel power take-off gear 39 is slid and meshed with the low speed gear portion 37, the front wheel automatic transmission changeover switch 63 is closed and the rotation of the drive pinion shaft 17 is transmitted to the first intermediate gear 35, and the first intermediate gear 35 is transmitted. Gear part of intermediate gear 35 37,3
The low speed side gear 27 and the high speed side gear 29 meshing with 8 rotate. Here, when the tractor 1 travels in the straight traveling state or the gentle turning state, the front wheels 44 are not steered to a position near the maximum steering angle, and the turning detection switch 59 is used.
Since the solenoid is open, the electromagnetic solenoid 50 is not energized and does not operate, and the pawl clutch body 24 is the pawl portion of the high speed side gear 29.
It is kept out of mesh with 31. Therefore, the low speed gear
The rotation of 27 is transmitted to the front wheel power take-off shaft 22 via the one-way clutch 30, and the front wheel 44 is driven at a peripheral speed substantially equal to that of the rear wheel 21.

Further, by engaging the front wheel power take-out gear 39 with the low speed gear portion 37, the front wheel automatic transmission changeover switch 63 is closed,
By operating the forward / reverse switching device 8 to move forward, the forward movement detection switch 62 is closed, and further, the auxiliary transmission 10 is operated to a shift position other than the high speed state or the creep device 11 is operated to creep. When the tractor 1 is traveling with at least one of the auxiliary gear shift detection switch 60 and the creep detection switch 61 closed, the steering device is steered to a position near the maximum steering angle to steer the tractor 1 rapidly. Turn. Then, the turning detection switch 59 that detects that the steering device has been operated up to the vicinity of the maximum steering angle is closed. As a result, the switches 59 to 63 arranged in series are closed and the electromagnetic solenoid 50 is energized to operate the electromagnetic solenoid 50, and the links 51, 53, 57 are pulled up as shown in FIG. At the same time, the shift arm 49 rotates. Then, the support shaft 46 rotates together with the shift arm 49, and further, the support shaft 46
The shifter fork 47 slides the pawl clutch body 24 toward the high speed side gear 29 by the rotation of the.
Mesh with. As a result, the rotation of the high speed side gear 29 is transmitted to the front wheel power take-off shaft 22 via the pawl clutch body 24, and the front wheel 44
Is driven to rotate at a high speed, and the tractor 1 turns with a small turning radius without causing skidding or the like.

Here, in order to improve the performance of releasing the engagement between the claw clutch body 24 and the claw portion 31, the claw clutch body 24 and the claw portion are improved.
As shown in FIG. 6, 31 and 31 mesh with each other at an angle of “θ ₁ ”. Therefore, the force in the disengagement direction that acts on the pawl clutch body 24, that is, the return force “P” that acts on the shift arm 49 also increases in proportion to the magnitude of the driving force transmitted. Then, this return force "P" causes an electromagnetic solenoid
A pressing force "P '" acts on 50, and this pressing force "P'" is P'when the complementary angle of the angle formed by the lift arm 49 and the second link 53 is "θ ₂ ". = P sin θ ₂ .

Further, the force "F" required to hold the electromagnetic solenoid 50 in the operating state is a value obtained by adding the spring force "S" of the return spring 58 to the pushing force "P '", and F = P sin θ ₂ It becomes + S.

Here, when the electromagnetic solenoid 50 is in operation, the shift arm 49 and the second link 53 are substantially perpendicular to each other, so that “θ ₂ ” is a small angle and the operation holding force “F” is small. The solenoid 50 can be downsized and a reliable operating state can be maintained. In addition, since the second link 53 and the third link 57 are substantially linear when the electromagnetic solenoid 50 is operated, the first link 51 has the pin 52
It is prevented from pivoting around and the first link 51 and the lift arm 49 are maintained in a substantially parallel state.

On the other hand, when the front wheel power take-out gear 39 is meshed with the second intermediate gear 36, the front wheel automatic transmission change-over switch 63 is opened, so that the electromagnetic solenoid 50 is de-energized and the drive pinion shaft 17 is rotated at the first position. Second middle gear
The front wheels 44 are rotationally driven by being transmitted from 36 to the low speed gear 16 and rotating the front wheel power take-off shaft 22 integrally with the low speed gear 16. In this traveling state, the peripheral speed of the front wheels 44 and the peripheral speed of the rear wheels 21 are substantially equal.

Effect of the Invention The present invention can transmit high torque by using the pawl clutch body in the high / low speed switching device that increases the peripheral speed of the front wheels during turning as described above.
By providing the high / low speed switching device including the claw clutch body in the front wheel power take-out case and providing the drive unit for sliding the claw clutch body outside the front wheel power take-out case,
The front wheel power take-out case can be downsized, and since it is not necessary to make the necessary electrical wiring in the drive unit through the front wheel power take-out case, the lubricating performance of the front wheel power take-out case can be reduced. In addition, since the shift arm and the second link are formed at a substantially right angle when the drive section is activated, the force in the disengagement direction generated at the meshing section between the claw clutch body and the high speed side gear causes The force acting on the drive unit in the direction opposite to the operating direction of the drive unit can be reduced, and therefore the drive unit can be downsized and the operating state of the drive unit can be ensured. Have the effect of.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a drive force transmission path diagram showing the entire drive force transmission path, FIG. 2 is a vertical sectional side view showing a front wheel power take-off portion, and FIG. FIG. 5 is a vertical sectional front view showing the front wheel power take-off portion. FIG. 4 is a front view showing a non-operating electromagnetic solenoid and a rotating state of the link and the like at that time.
FIG. 6 is a front view showing an electromagnetic solenoid in an operating state and a rotating state of a link etc. at that time, FIG. 6 is a development view showing a meshing state of a claw clutch body and a claw portion of a high speed side gear, and FIG. 7 is an electromagnetic solenoid. FIG. 8 is a side view showing the whole of the tractor, showing an open circuit showing the energized state of the tractor. 1 ... four-wheel drive vehicle, 6 ... front wheel power take-out case, 21 ...
… Rear wheel, 22 …… Front wheel power take-off shaft, 24 …… Claw clutch body,
27 …… Low speed side gear, 29 …… High speed side gear, 30 …… One way clutch, 44 …… Front wheel, 49 …… Shift arm, 50 ……
Drive unit, 51 …… first link, 53 …… second link

Claims (1)

(57) [Scope of utility model registration request] 1. A four-wheel drive vehicle in which a rear wheel and a front wheel connected to a front wheel power take-off shaft are respectively driven, and a low speed side gear and the front wheel power attached to the front wheel power take-out shaft via a one-way clutch. A high speed side gear rotatably mounted on the take-out shaft and a front wheel power take-off shaft are slidably fitted to the claw clutch body that engages and disengages with the high speed side gear in response to a steering operation of a steering device. And a drive unit for sliding the pawl clutch body is provided outside the front wheel power take-out case, and a rotatable shift arm connected to the pawl clutch body is provided. And a first link connected to the drive unit are arranged substantially in parallel, and the shift arm and the first link are rotatably connected via a second link. The front wheel of a four-wheel drive vehicle, wherein the shift arm and the second link are set to be substantially at a right angle when the claw clutch body and the high speed side gear are engaged by the operation of the drive section. Gearbox.