JPH0463727A - Final speed reducer - Google Patents

Abstract

PURPOSE:To eliminate a severe limitation for preventing the rotary unbalance of a rotation difference sensitive joint by integratedly forming one side of two members of a relatively rotatable hydraulic coupling on one side side gear of a differential gear, and connecting the other side of the two members to an output shaft on the side gear side. CONSTITUTION:In a front-wheel drive base four-wheel drive vehicle, motive power from a transmission output gear is made to be transmitted to a rear differential device 14 from a rear propeller shaft 11 via a drive pinion 12 and a ring gear 13. Then constitution is made in which motive power can be transmitted to a right rear wheel from one side gear 15 of the rear differential device 14 directly via a rear drive shaft 16 and to a left rear wheel from the other side side gear 17 via an orifice coupling 18 (rotation difference sensitive joint) and a rear drive shaft 19. This can ease designing by eliminating the need for severely limiting the rotary unbalance of the orifice coupling 18 by giving low rotation, having passed a final reduction gear ratio with the rear differential device, to the orifice coupling 18.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a final reduction gear for use in four-wheel drive vehicles, in which driving force is equally distributed between the front and rear wheels according to the difference in rotational speed between the front and rear wheels. Regarding.

(Prior art) Conventionally, as four-wheel drive vehicles that continuously use a viscous coupling, which is an example of a rotation difference sensitive joint, examples include Eva, Ii',
t-roo f-4WOJJ (December 1988:
It is known that it is described on pages 210 to 228 of [Published by Railway Japan Co., Ltd.].

In addition to the center viscous coupling, which is installed on the propeller shaft to the rear wheels and distributes driving force according to the difference in rotational speed between the front and rear wheels, this conventional model also has a differential limiter for the front and rear differential gears. Triple viscous coupling using a highly functional viscous coupling
Full-auto full-time 4WD is shown.

(Problems to be Solved by the Invention) However, the above-mentioned conventional technology has the following problems.

■ The center viscous coupling is installed on the propeller shaft, and because it is installed so that high rotation is applied directly from the output side of the transmission connected to the engine (without passing through the final reduction gear), the center viscous coupling Unless the roundness of the ring's drive plate and the accuracy of input to the center of the drive plate are extremely high, vibration and noise will occur due to the rotation of the plate (hereinafter referred to as rotational imbalance), and this rotational imbalance will occur. This causes vibrations to the vehicle.

■ Since the unit with the center viscous coupling is a relatively independent mass, the mass that allows heat is small, and if the difference in rotational speed between the front and rear wheels continues and generates heat, the temperature will rise rapidly.

■ Also, in order to simply solve the above problem (■), a viscous coupling is attached to a drive shaft that is decelerated by a reducer, for example, in Japanese Patent Application Laid-open No. 62-244.
No. 715, Japanese Unexamined Patent Publication No. 6.2-253526, etc. However, in the devices proposed in these publications, a viscous coupling is provided outside the case of the front differential gear and separate from the case, resulting in an increase in the size of the power transmission system itself. There is a risk of interference with other members inside.

The present invention has been made in view of the above-mentioned problems, and there is no severe restriction to prevent the rotational imbalance of the rotation difference sensitive joint, and moreover, it is rigid while suppressing the temperature rise after generation of heat. The purpose of the present invention is to provide a final reduction gear that exhibits front and rear wheel drive force distribution functions including characteristics similar to those of 4WD, and is further miniaturized.

(Means for Solving the Problems) In order to solve the above problems, in the final reduction gear of the present invention, one of the two members of the fluid coupling that is relatively rotatable is formed in one side gear of the differential gear, and this side gear example The other of the two members was connected to the output shaft of.

That is, a pinion is rotatably supported via a pinion shaft in a differential case connected to the drive input side, a pair of side gears mesh with the pinion, and one of the two output shafts is connected to the pair of side gears. is directly connected to one of the side gears of the pair, forms one of two members of a fluid coupling that can rotate integrally with the other of the pair of side gears, and the other of the two members is connected to the output shaft of the other. It is characterized by

(Function) When driving at a constant speed on a high μ road, if the rotational speeds of the side gear and output shaft corresponding to the front and rear wheel rotational speeds are the same, relative rotation occurs between the two members. There is no torque transmission. Therefore, the engine driving force is transmitted almost only to the side directly connected to the engine.

When a difference in rotational speed occurs between the front and rear wheels due to drive shaft slip when starting, accelerating suddenly, or driving on a low μ road, the rotational speed of the side gear corresponding to the rotational speed of one of the front and rear wheels will change to the output corresponding to the rotational speed of the other. The rotational speed of the shaft is higher than that of the shaft, and relative rotation occurs between the two members depending on the degree of drive shaft slip.

In this case, torque is transmitted between the fluid couplings due to this relative rotation, and this transmitted torque is directly transmitted to one wheel side, and the same torque is also transmitted to the other wheel side via the pinion and side gear. communicated.

(First example) First, the configuration of the embodiment will be explained.

FIG. 1 is a sectional view showing the final reducer of the first embodiment,
FIG. 2 is a sectional view taken along the line II in FIG. 1, and FIG. 3 is a power train skeleton diagram of a front-wheel drive base four-wheel drive vehicle in which the final reduction gear of the first embodiment is used.

In FIG. 3, the engine driving force to the front wheels 1.2 is transmitted from the transmission output gear 3 to the front differential case 4.2. The signal is transmitted through the front differential gear 5 and the left and right front drive shafts 6.7.

Engine driving force is not transmitted to the rear wheels 8.9 when there is no difference in rotational speed between the front and rear wheels, and when a difference in rotational speed between the front and rear wheels occurs, engine driving force is transmitted according to the magnitude of the difference in rotational speed between the front and rear wheels.

That is, from the transmission output gear 3 to the front differential case 4. Transfer gear unit 10. Rear propeller shaft 11. Drive pionion 12. Ring gear 13. rear differential 1
4, the transmission is directly transmitted from one side gear 15 of the rear differential 14 to the right rear wheel 8 via the rear drive shaft 16, and the transmission is transmitted from the other side gear 17 to an orifice coupling 18 (rotation difference sensitive joint) and It is transmitted to the left rear wheel 9 via the rear drive shaft 19.

As shown in FIG. 1, the rear differential 14 is rotatably supported via a differential case 20 to which driving force is input via a drive pionion 2 and a ring gear 13, and a pinion mate shaft 21. It includes a pinion 22 and a pair of side gears 15 and 17 that mesh with the pinion 22.

As shown in FIGS. 1 and 2, the orifice coupling 1 is installed in the side of the side gear 17 of the rear differential 14, and the side gear 17 is integrally formed with the side gear 17. a cam housing 31 (housing member) having a cam surface 30 formed on its inner surface; a rotor 32 (rotor member) spline-coupled to the drive shaft 19 (output shaft); Six driving pistons 33 (cam bodies) arranged radially at equal intervals reciprocate in the radial direction while slidingly contacting a cam surface 30 formed on the inner surface of the cam surface 30, and a plurality of driving pistons 33 whose volume changes as the driving pistons 33 reciprocate. A regulator equipped with a cylinder chamber 34, an orifice 37 provided in a discharge passage 36 that communicates each cylinder chamber 34 with an accumulator chamber 35, and a one-way valve 38 that allows flow only from the accumulator chamber 35 to each cylinder chamber 34. It has an oil passage 39.

The accumulator chamber 35 is a chamber that temporarily stores and releases hydraulic oil to absorb an increase or decrease in the amount of oil, and includes an accumulator piston 40 provided in an oil-tight manner on the inner surface of the cylinder portion of the rotor 32 so as to be able to reciprocate and slide; A spring 4 interposed between the piston 40 and the spring retainer 41
2. A plurality of relief holes 44 are opened in the radial direction in the rotor portion corresponding to the position where the piston seal 43 is provided, and functions as a relief valve to discharge hydraulic oil when the accumulator chamber 35 exceeds the set pressure. I try to do that.

Next, the effect will be explained.

(a) Torque transmission and rotation effect Regarding torque transmission between the left and right rear wheels 8 and 9, the torque input from the differential case 20 to the cam housing 31 via the pinion mate shaft 21 and pinion 22 is caused by the hydraulic reaction caused by the driving piston 33. The force is transmitted from the rotor 32 to the left drive shaft 19. The left drive shaft 19 and the right drive shaft 16 are connected to each other because the left and right side gears 15.17 mesh with the same pinion 22 and are balanced at this pinion 22, so both drive shafts 16.19
The same torque is transmitted to

Regarding the rotation of the left and right rear wheels 8.9, when the left and right drive shafts 16.19 are running straight ahead with equal rotational resistance and there is a difference in rotational speed between the front and rear wheels, the cam housing 31 rotates the left drive shaft 16.9. The drive shafts 16 and 19 rotate at the same speed as the torque transmitted to the shaft 19, but because the pinion 22 rotates between them and the differential case 20, the left and right drive shafts 16 and 19 rotate at the same speed.

(b) Front and rear wheel drive force distribution effect When driving at a constant speed on a high μ road, etc., the rotation speed of the side gear 17 corresponding to the front wheel rotation speed and the rotation speed of the left drive shaft 19 corresponding to the rear wheel rotation speed are different. If they are the same, no relative rotation occurs between the cam housing 31 and the rotor 32, no reciprocating movement of the driving piston 33 occurs, and no torque is transmitted via the orifice coupling 18. Therefore, there is almost no torque transmission to the left and right rear wheels, and the driving force distribution to the front wheels 1 and 2 is 10.
0% shows the character of a front wheel drive car.

However, when starting, accelerating suddenly, or driving on a low μ road, the front wheel 1.
When a rotational speed difference occurs between the front and rear wheels due to drive wheel slip in No. 2, the rotational speed of the side gear 17 corresponding to the front wheel rotational speed changes to the left side drive shaft 1 corresponding to the rear wheel rotational speed.
The rotational speed of orifice coupling 1 is higher than that of 9.
Relative rotation occurs between the cam housing 31 of No. 8 and the rotor 32 depending on the degree of drive wheel slip.

In this case, due to this relative rotation, the driving piston 33 in sliding contact with the cam surface 30 reciprocates in the radial direction.
When trying to reduce the volume of the driving piston 33, the pressure inside the cylinder chamber 34 increases due to the flow resistance caused by the outflow restriction by the orifice 3Y. This pressing force becomes a transmission torque of the orifice coupling 18, and this transmission torque is directly transmitted to the left rear wheel 9 side, and the same torque is transmitted via the pinion 22 and the side gear 15. It is also transmitted to the right rear wheel 8 side.

That is, as shown in FIG. 4, the rear wheel side transmission torque characteristic exhibits a characteristic in which the rear wheel side transmission torque TR increases in a quadratic function curve as the front and rear wheel rotational speed difference ΔN increases. Note that when the vehicle speed V is high, such as when driving at high speed, a transmission torque ΔK due to the centrifugal force applied to the driving piston 33 is added as shown by the dotted line characteristic in FIG. 4, corresponding to the vehicle speed V. Indicates the characteristics/characteristics that have been achieved.

As explained above, in the final reduction gear of the first embodiment, the effects listed below can also be obtained.

■ Since the orifice coupling 18 is provided downstream of the rear differential gear 14, the orifice coupling 18 is connected to the rear differential gear 1.
Since a low rotation that has passed the final reduction ratio of 4 is given, there is no need to strictly limit the rotational imbalance of the orifice coupling 18, and the design becomes easy.
Vibrations imparted to the vehicle due to rotational imbalance can also be reduced.

Furthermore, in order to avoid interference with ABS (anti-skid braking system), etc., it is necessary to allow a large amount of relative rotation, but since the relative rotation is smaller on the drive shaft than on the propeller shaft, the ABS It also becomes easier to design countermeasures against interference with other objects such as the like.

■ Side gear 17 of rear differential gear 14
Because the orifice coupling 18 is built into the side of the engine, it is cooled by oil from the surrounding area, and the mass of the unit containing the orifice coupling 18 is large to allow heat, resulting in a continuous difference in rotational speed between the front and rear wheels. Even in such a case, the temperature rise of the orifice coupling 18 can be suppressed.

■ The torque characteristics transmitted by the orifice coupling 18, as shown in FIG.
When transmitting horsepower, it is essentially more advantageous to transmit large torque with a small rotational difference than with a large rotational difference and small torque, so it is more practical than a viscous cuff spring. , Rigid 4WD is a marginal characteristic because a large torque increase is seen in the high rotational speed difference area.
characteristics can also be obtained.

■ This orifice force/combination 18 can be applied to the orifice cup without changing the positional relationship with the rear differential gear 14 at all, just by changing the connection relationship from gear shaft to shaft-shaft or case-shaft. Since the ring 18 can be used as a differential limiting device for the left and right rear wheels, two units with different characteristics can be manufactured on one production line.

(Second Embodiment) Next, the final reduction gear of the second embodiment will be described based on FIGS. 5 and 6.

The final reduction gear of this second embodiment uses an orifice coupling with a variable orifice, whereas the final reduction gear of the first embodiment uses an orifice coupling with a fixed orifice.

Structurally, instead of the orifice 37 of the first embodiment, a variable orifice 37a whose orifice opening area is changed depending on the stroke position of the spool 50, and the variable orifice 3
A fixed orifice 37b is provided which is activated when 7a is fully closed.

The operating mechanism of the spool 50 includes a bushing rod 51, a cross rod 52, an inner sleeve 53, a bearing 54, an outer sleeve 55, a fork 56, and a fork shaft 57, and the fork shaft 57 is driven by a step motor (not shown) or the like. Its rotation angle is controlled.

Note that the other configurations are the same as those in the first embodiment, so corresponding configurations are given the same reference numerals and explanations will be omitted.

Next, the effect will be explained.

The opening area of the variable orifice 37a is controlled by a drive command from a driving force distribution characteristic control circuit connected to the step motor, etc. As shown in FIG. 6, the orifice opening area is small and the oil The stricter the outflow regulation, the higher the rear wheel side transmission torque characteristic is such that the increase gain of the rear wheel side transmission torque TR with respect to the increase in the front and rear wheel rotational speed difference ΔN becomes higher.

Therefore, for example, during normal driving, the opening area of the variable orifice 37a is changed and controlled so that the optimum driving force distribution characteristic can be obtained depending on the driving situation, such as making it smaller when driving straight and larger when turning. If you want to obtain rigid 4WD characteristics when driving on low μ roads or rough roads, use the variable orifice 37a as shown in the lower half of Fig. 5.
is fully closed, and the driving force distribution control is performed using the characteristic that the increase gain of the rear wheel side transmission torque TR is the highest only with the fixed orifice 37b.
When S is activated, as shown in the upper half of Figure 5, the variable orifice 37a is fully opened, the front wheel drive state is ensured, and the four-wheel drive is directly connected, so that the braking torque is increased on each vehicle. Even though the ABS is controlled, braking torque is transmitted to all four wheels, thereby impairing the original operation of the ABS.Control is performed to prevent control interference with the ABS.

Note that other functions are the same as in the first embodiment.

Therefore, in this second embodiment, in addition to the effects (1) to (4) above, the following effects can be obtained.

■ Since the orifice coupling 18 is installed on the drive shaft, which rotates at a low speed after reaching the final reduction ratio of the rear differential gear 14, a variable orifice structure that changes the driving force distribution characteristics can be easily applied. .

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, an example of application to a torque split four-wheel drive vehicle based on front wheel drive was shown, but as shown in the power train skeleton diagram of FIG. 7, the orifice coupling 18 may be applied to the front differential 5 side. The orifice coupling 18 with a fixed orifice or a variable orifice may be applied to a torque split four-wheel drive vehicle based on rear wheel drive.

(Effects of the Invention) As explained above, in the final reduction gear of the present invention, one of the two relatively rotatable fluid coupling members is integrally formed with one side gear of the differential gear, and the side gear of this side gear is Because the other of the two members is connected to the output shaft, there are no strict restrictions to prevent the rotational imbalance of the joint, and while minimizing the temperature rise after heat generation, the front and rear wheel drive force has characteristics close to that of a rigid 4WD. The effect is that it is possible to provide a final reduction gear that exhibits a distribution function, is small, and does not cause interference with other components.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional plan view showing the final reduction gear of the first embodiment of the present invention, FIG. 2 is a longitudinal sectional front view showing the orifice coupling of the final reduction gear taken along line I-I in FIG. 1, and FIG. A powertrain skeleton diagram of a front-wheel drive base four-wheel drive vehicle to which the final reduction gear of the first embodiment is applied, Fig. 4 is a rear wheel transmission torque characteristic diagram of the final reduction gear of the first embodiment, and Fig. 5 is a diagram of the present invention. 6th vertical sectional plan view showing the final reduction gear of the second embodiment of the invention;
FIG. 7 is a rear wheel side transmission torque characteristic diagram of the final reduction gear of the second embodiment, and FIG. 7 is a power train skeleton diagram of a front-wheel drive base four-wheel drive vehicle to which the final reduction gear of the second embodiment is applied. 14...Rear differential gear 15.17...
-Side gear 16.19-...Drive shaft (output shaft) 18...
- Orifice coupling (differential rotation sensitive coupling) 20...Differential case 21...Pinion mate shaft 22...Pinion 30...-Cam surface 31...Cam housing (housing member) 32...
・Rotor (rotor member) 33-...Driving piston (cam body) 34...-
Cylinder chamber 35...Accumulator chamber 36...Discharge oil passage 37...Orifice

Claims (1)

[Claims] 1) a pinion rotatably supported via a pinion shaft in a differential case connected to the drive input side; a pair of side gears meshing with the pinion;
One of the two output shafts is directly connected to one of the pair of side gears, and forms one of two members of a fluid coupling that is integrally rotatable relative to the other of the pair of side gears, and A final reduction gear characterized in that the other of the two members is joined to the output shaft of the other.