JPH0266341A - Worm gear type differential gear - Google Patents

Abstract

PURPOSE:To enable the escape at the time of a single wheel being removed by providing an energizing means for energizing thrust washers in the direction of pressing the thrust washers to the end part of a worm gear between the thrust washers at the end of at least one worm gear and a differential case. CONSTITUTION:Washers 17L, 17R are pressed on the end parts of worm gears 13L, 13R by an energizing means such as coil springs 17L, 17R and the like interposed between thrust washers 15a, 15b, 16a, 16b and a differential case 11 so that the thrust force is constantly added between the thrust washers and worm gears. Accordingly, the driving force of an axel is increased by the pressure part provided by the energizing means compared to the case without an energizing means, and for example, even in case one wheel comes off and is in the complete slipping state, the torque bias effect against the other axel can be maintained.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a worm gear type differential gear device.

(Conventional technology) As a conventional worm gear type differential gear device.

There is one described in Utility Model Application Publication No. 130-500009. This conventional worm gear type differential gear device is
As shown in FIG. 11, a left axle 2L and a right axle 2R are fitted to a rotating shaft 2 coaxially from the left and right sides of a differential case (hereinafter referred to as a differential case) 1, and the inner ends of the left and right axles 2L and 2R. The left and right worm gears 3L and 3R are spline-fitted to the left and right worm gears 3L and 3R, respectively, and the left and right worm gears 3L and 3 are rotatably attached to the differential case 1.
1 meshing with R (several pairs of left worm wheel 4L and right worm wheel 4R, left and right worm gears 3L, 3
Thrust element 5 interposed between R, thrust bearing 6 interposed between left worm gear 3L and inner wall of differential case 1. and a spacer 7 interposed between the right worm gear 3R and the inner wall of the differential case 1. The teeth of the left and right worm gears 3L and 3R were twisted in the same direction.

This worm gear type differential gear device transmits the rotational torque transmitted to the differential case 1 via the ring gear 8 to the left and right axles 2L, 2R via the worm wheels 4L, 4R and the worm gears 3L, 3R, respectively. Rotate the wheels.

When the vehicle is traveling straight, the wheels on both sides rotate at the same rate, so differential case 1. Worm wheel 4L,
4R and worm gear 3L.

3R rotates integrally, and the rotational torque from the ring gear 8 is equally distributed between each member and between the left and right vehicles 2L,
No relative rotation occurs between 2R.

However, if there is a difference in rotation between the wheels on both sides when the vehicle is turning, or if one wheel slips on muddy or snowy roads, resulting in different wheel resistance on both sides, the wheels may not mesh with each other. The rotational torque from the ring gear 8 is appropriately distributed to the left and right vehicles 2L and 2R by the left and right worm wheels 4L and 4R, which are interlocked with each other.
Relative rotation occurred between the worm gears 3L and 3R and the differential case 1. The south face between the worm wheels 4L, 4R and the worm gears 3L, 3R, the worm gears 3L, 3R and the thrust element 5. A torque bias effect was obtained by the friction torque generated on each friction surface between the thrust bearing 6 and the spacer 7.

In such a torque proportional differential gear device, due to the torque bias effect during differential operation.

The axle on the high-speed rotating side! - If the torque is T and the axle torque on the low speed rotation side is T2.

T2-tT.

[: Torque bias effect A relational expression is established.

(Problem to be Solved by the Invention) However, in the conventional worm gear type differential gear device as described above, as can be seen from the above-mentioned relational expression, when the high-speed rotation side axle torque T1 is zero, the low-speed rotation side axle Torque T2 also becomes zero.

Therefore, 3. For example, if one wheel comes off the wheel and becomes completely floating, and that wheel spins and the wheel resistance becomes zero, the torque T1 of that wheel becomes zero, and as a result, the other axle also There was a problem in that the shaft torque became zero and the vehicle could not escape from the off-road condition. This is because when the wheel is idling, the wheel resistance becomes zero and the reaction force from the worm gear on the middle wheel side disappears, so all the rotational torque from the ring gear is transmitted to the worm gear on the idling side.

This invention has been made in order to eliminate the drawbacks of the conventional worm gear type differential gear device as described in 1-. That is, one object of the present invention is to provide a worm gear type differential gearing device that can transmit φ1 torque to the other wheel even when one of the two wheels is idling.

(Means for achieving the task) This invention aims to achieve the above object.

A pair of worm gears are housed in the differential case so as to rotate integrally with the inner ends of the left and right IF shafts, and a thrust washer is interposed between the ends of the worm gears and the differential case. , a worm gear type differential that transmits synchronous torque from the differential case to the worm gear through a pair of worm wheels that are rotatably installed in the differential tooth around the axis of the worm gear and mesh with the worm gear so as to rotate in conjunction with each other. In the gear device, a biasing means for biasing the thrust washer in a direction to press the end of the worm gear is provided between the thrust washer at the end of at least the -j worm gear of the pair of worm gears and the differential case. It is characterized by the following.

(Function) The worm gear type differential gear device transmits rotational torque from the engine, which is transmitted to the differential case, to the worm gear via the worm wheel to rotate the left and right axles. When the axle moves straight, the differential teeth, worm wheel, and worm gear rotate as a unit to equally distribute rotational torque to the left and right.

When the left and right heavy wheel resistance is different, such as when the vehicle is turning or when one wheel slips.

Relative rotation occurs between the differential case, the middle wheel, and the worm gear, creating a differential between the left and right wheels, and a torque proportional differential limiter due to the torque bias effect caused by the friction torque between the worm gear and the thrust washer. Functions as a device.

Here, the worm gear type differential gear bag ij? according to the present invention? c.
is characterized by the fact that the thrust washer is pressed against the end of the worm gear by a biasing means such as a spring interposed between the thrust washer and the differential case, and a thrust force is constantly applied between the thrust washer and the worm gear. has been done. Therefore, the driving force of the axle is
Compared to the case where there is no biasing means, the amount of pressurization by the biasing means increases.1For example, even if one wheel comes off the wheel and completely spins, the torque bias effect on the other axle will be Keep it! ! be done.

In one embodiment of the present invention, the biasing means may be provided at both ends of a pair of worm gears, only at the end of the right worm gear, or only at the end of the left worm gear.

(Example) Hereinafter, this invention will be described in further detail based on an example shown in the drawings.

In Figs. 1 and 2, 11 is a differential case (hereinafter referred to as a differential case), and 12L and 12R are each housed in a pair inside the inner peripheral part of the differential case 11, and are rotatable in the differential case so that their axes are perpendicular to the axis of the differential case. Supported by Southern 12L a,
A left worm wheel and a right worm wheel that mesh with each other and rotate simultaneously by +2Ra, 1
3L and 13R are housed in series in the differential case 11 so as to be coaxial with the differential case, and each has a tooth portion 13 on the outer periphery.
L a and +3Ra mesh with the teeth 12Lb and 12Rb of the left worm wheel 12L and right worm wheel 12R, and splines 13Lb and +3Rh on the inner circumferential portion are a left worm gear and a right worm gear respectively connected to a left axle and a right axle (not shown). Yes, 14a, 14b, 14c
Thrust washers*, 15a, 15b are interposed between the left worm gear 13L and the right worm gear 13R.
are thrust washers interposed between the left worm gear 13L and the inner wall surface of the differential case 11;
b is a thrust washer interposed between the right worm gear 13R and the inner wall surface of the differential case 11, and the structure up to this point is almost the same as a conventional worm gear type differential gear device.

1.8 The differential case 111 is located on the inner wall facing the back of the thrust washer +5a and tea.

Spring holes +1A and IIB are formed respectively. These spring holes 11A and IIB are usually 9.
6 along the circumferential direction on both left and right sides respectively
They are arranged at equal angular intervals from 1 to 10tP. Coil springs 17L, 17R are inserted into the spring holes 11A, ILB in a compressed state, and thrust washers 15a, 1.5b and IGa, 1 (ib are respectively connected to worm gears 13L, 13).
Press it toward the R side] is biased in the j direction.

1: The differential toothing device uses rotational torque manually applied from a ring gear (not shown) as in the conventional case.

Differential case 11 - left and right worm wheels 12L
, +2R-Left and right worm gear 13L.

+31 to the left and right axles.

And when the vehicle is driving straight, use the differential case! ! , worm wheel +2L and 12R, worm gear 13
L and 13R rotate together and equally distribute rotational torque to the axles on both sides of 9.

Furthermore, when the middle wheel turns, the rotational torque from the differential case 11 is distributed by the left and right worm wheels 12L and 12R, which rotate in conjunction with each other, in accordance with the ratio of heavy wheel resistance acting on the wheels on both sides. and left and right worm gears 13L.

It is transmitted to 13R. At this time, the differential case 11, the left and right worm gears 13L and 13R, and the left and right worm gears rotate relative to each other, causing the left and right axles to differentially move.

Here, each 4--Mugia 13L, southern part of L3R 13L
a 1.3Ra are both left-handed threads, and the forward direction of the vehicle is from the front to the back of the paper in Fig. 2. When the φ vehicle moves forward, the rotation of the differential case 11 causes the worm wheels 12L, 12R and Worm gear 1
Due to the frictional force between 3L and 13R.

As shown in the figure, a thrust force F111 acts in the left axis direction, and a thrust force F1 in the t1 direction is further applied by pressurization by the coil spring 17R.

p2 When the vehicle turns, each element of the differential gear unit rotates in the same direction relative to each other, causing the thrust washers between the differential case and each worm gear and between the left and right worm gears to slide, each generating friction torque. do. As is well known, sliding in the thrust washer occurs on the surface where the friction torque is minimum, ie, 1!4+fit, which means that if the surface diameters are the same, the friction coefficient is the smallest. In this embodiment, the right side of the thrust washer 15a is located between the differential case 11 and the left worm gear 13L, and the left side of the thrust washer L4b is located between the left worm gear 13L and the right worm gear 13R.
Assuming that the right worm gear 13R and the differential case 11 slide on the left side of the thrust washer lea, the right side of the thrust washer 15a, the left side of the thrust washer 14b, and the thrust! - The coefficient of friction on the left side surface of the washer 16a is μ, μ2. μ3. Let the diameter of each friction surface be R, R2, R ('R-R2-R3) 1
Do 3.

For example, when the vehicle is moving forward and turning to the right, the left worm gear 13L is on the high speed rotation side and the right worm gear 13R is on the low speed rotation side, and the axial thrust force exerted by the meshing with the worm wheels is Worm gear 1.3L is F, right hl worm gear 13R is F. Then, drive torque of left worm gear 13L on high speed side h2 is T low speed g1
The driving torque of the right worm gear 13R on the ' side is 1g2,
The left axle torque T1 on the high speed side and the mountain torque T2 on the stone wheel on the low speed side are.

TI””r);l ”2 ”’2’ (Tth
2”'5p2)”I “l” (TLhl+Tth
2+Fsp2) D2 ” 'P2 + R2・R2
・ (Tlh2”'5p2) 10 μ3 ・R3・ ”
It is represented by sp2.

Expand and organize the notation.

T - t - T1 + C (1) t: torque bias ratio C: constant. Therefore, the driving force T of both wheels is T-T +
T2-(1+tl T1-1-C...(2).

Here, in the conventional differential gear device without pressurization by the coil spring 17R, as described above.

'r2' -t T1' -(3)(
:Torque bias ratio (same value as in equation (1)), and the driving force T for both wheels is.

T-(t+1)T,' ...(4), so when comparing equations (2) and (4), equation (2) has a higher driving force by the preload C due to the coil spring 17R. becomes larger.

From equation (1), even if the left wheel comes off the wheel and spins, and the left center axle torque TI becomes zero, the right axle torque T2 becomes 2-C and becomes zero. There isn't.

Figure 4 is an LSD performance diagram based on the calculation results described in 1-1, where the T line represents the driving force for both wheels, the Tl line represents the axle torque on the high-speed side, and the T' line represents the conventional differential gear system. This represents the two-wheel driving force. As is clear from this figure, the two-wheel driving force T in the present invention is larger than the conventional two-wheel driving force T' by the driving force C corresponding to the pressurization, and even when the high-speed side axle torque T becomes zero, the driving force T -C and never becomes zero.

Note that the two-wheel drive force T changes at point α.

This is because if the road surface friction coefficient of the tire on the high-speed rotation side becomes larger than that, the tire will reach its slip limit.

Note that the explanation above is for the case where the vehicle moves forward and turns to the right, but when the vehicle moves backward or turns to the left, the same result will be obtained by simply switching the high speed side and low speed side of the worm gear.

Further, the following is as shown in the schematic diagram of FIG.

This is an example in which pressurizing coil springs 17L and 17R are attached to both sides of worm gears +3L and +3R, but as shown in Fig. 5, coil springs +7
R may be attached only to the right end of the right worm gear 13R, and the LSD performance diagram in this case is as shown in Fig. 6, and compared to Fig. 4, the characteristic when moving forward is T line, and when retreating it is T line. The characteristics are as shown by the TJr line. In addition, as shown in Fig. 7, the coil spring 17L is connected to the left worm gear 13L.
The LSD performance diagram in the case where the LSD is installed only at the left end is as shown in FIG. 8, with the characteristic when moving forward being as shown by the T line, and the characteristic when reversing being as shown by the T' line. In any case.

1? Compared to the conventional system, even when the driving torque of the high-speed rotation side heavy wheels is zero, the drive torque of the low-speed rotation side wheels maintains the pressurized bone C by the coil spring. Furthermore, worm gear 13L.

When coil springs are installed on both sides of the 13R, even if the spring constants of the coil springs on both sides are set to different values, the low-speed rotation side wheel can maintain the driving torque at least by the pressurized bone by the coil springs. case L
The SD performance diagram has characteristics approximately between those in FIG. 6 and FIG. 8.

Also, as a method for pressurizing thrust washers.

In addition to the embodiment shown in FIG. 2, a pair of springs 2OL and 2OR may be interposed at both ends of the worm gears 13L and 13R so as to be coaxial with the worm gears 13L and 13R, as shown in FIG. Furthermore, as shown in Fig. 10, a pair of disc springs 30L and 30R may be interposed on both sides of the worm gears 13L and 13R instead of the coil springs, and various other methods may be used as pressurizing means. It is Noh.

(Effects of the Invention) As described below, according to the present invention, the thrust washer is pressed against the end of the worm gear by the urging means, such as a spring, interposed between the thrust washer and the differential case. Since a thrust force is always applied between the worm gear and the worm gear, the driving force of the axle increases by the amount of pressure applied by the urging means compared to the case without the urging means. Even when completely idling, the torque bias effect on the other axle is maintained.

Therefore, even if the wheel on the high-speed rotation side spins and the wheel resistance becomes zero, the driving force for the other wheel is ensured.
Escape is possible when one wheel comes off.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
3 is a schematic diagram showing the configuration of the same embodiment, FIG. 4 is an LSD performance diagram in the same embodiment, and FIG. 5 is a diagram showing another embodiment of the present invention. Schematic configuration diagram 2 FIG. 6 is an LSD performance diagram in the same embodiment, FIG. 7 is a schematic diagram showing still another embodiment of the present invention, and FIG. 8 is an LSD performance diagram in the same embodiment. FIG. 9 is a sectional view showing still another embodiment of the present invention, FIG. 10 is a sectional view showing still another embodiment of the invention, and FIG. 11 is a sectional view showing a conventional example. 11... Differential case 11A, IIB... Spring hole +2L, +2R... Worm wheel 13L,
+3R... Worm gear 15a, 15b,
Thrust washer for lea, 10b +7L,
+7R...Coil spring 20L, 20R...
・Springs 30L, 30R...Disc spring applicant Aisin Seiki Co., Ltd. Agent Patent attorney Asa Kato Road Figure 3 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] A pair of worm gears are housed in the differential case, each attached to the inner end of the left and right width shafts so as to rotate together, and a thrust washer is interposed between the end of the worm gear and the differential case. In the worm gear type differential gear device that transmits rotational torque from the differential case to the worm gear through a plurality of pairs of worm wheels that are rotatably installed in the differential case around the periphery and mesh with the worm gear so as to rotate in conjunction with each other, A worm gear characterized in that a biasing means for biasing the thrust washer in a direction to press the end of the worm gear is provided between the thrust washer at the end of at least one of the pair of worm gears and the differential case. type differential gearing.