JPS60164046A - Differential gear device - Google Patents

Abstract

PURPOSE:To enhance the efficiency of power transmission, by attaching a cover onto the top of a bolt for securing a ring gear to a differential casing. CONSTITUTION:The drawing shows a differential gear device in which the transmission of a transversely laid engine is integrally incorporated with a front wheel differential gear, and which is what we call as ''FF transaxle''. Since the differential gear device 2 is positioned below a transmission 5, a substantially entire part of a differential carrier 4 is submerged in lubrication oil as indicated by the oil level L. A ring gear 7 is attached to the differential gear 12 by being fastened to a flange section 13 integrally incoporated with the outer periphery of the differential gear 12, by means of a bolt 16. With the use of this bolt 16, a support piece 19 for a cover 20 is secured to the above-mentioned flange section 13, and the cover 20 is attached thereto for covering the outside of a head 18, thereby the fluid resistance coefficient is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of differentials in automobiles, and more specifically, the present invention relates to improvements in differentials in automobiles, and more particularly, protrusions such as the heads of bolts for fixing a ring gear to a differential case can absorb oil filled in a differential carrier. This invention relates to something that reduces loss caused by stirring and improves power transmission efficiency.

Differentials in automobiles were developed in 1986-7.
As shown in Publication No. 2956, a differential case in which a differential pinion meshing with left and right differential side gears directly connected to an axle is supported via a differential pinion shaft,
The differential carrier is rotatably housed and supported, and a ring gear is fixed to the differential case, and the drive pinion at the tip of the propeller shaft is meshed with the ring gear to transmit driving force to the differential. ing. The differential carrier is filled with lubricating oil, and the ring gear or differential case rotates at the same rotation speed as the average rotation speed of the left and right drive wheels when the vehicle is running.

Transfer efficiency η when focusing on differential
is expressed as T2 Tlxi-T3 where TI is the input torque, T2 is the output torque, T3 is the total loss torque, and i is the reduction ratio. As is clear from this equation, as the total loss torque T3 increases, the transmission efficiency η decreases.

Here, the loss torque changes as the input rotational speed changes as shown in FIG. As is clear from this figure, as the input rotational speed increases, the loss torque increases exponentially. The breakdown of the total torque loss includes oil stirring loss, oil seal loss, gear engagement loss, and bearing loss, but losses other than oil stirring loss are due to boundary friction, which is close to dry friction among sliding friction. This is caused by the fact that Coulomb's law of friction is applied approximately, so it is considered to be approximately constant over the entire input rotational speed range. Therefore, since the drag force of an object moving in a viscous fluid is generally proportional to the square of its speed, the exponential curve in Figure 1 is an oil stirring force that is considered to be proportional to the square of the input rotation speed. It seems that the influence of heat loss is particularly large in the high rotational speed range. For these reasons,
If the oil stirring loss could be significantly reduced, it would greatly contribute to reducing the total loss, and in turn, it would be possible to improve the transmission efficiency η.

Based on the above-mentioned viewpoint, the present invention eliminates as much as possible the protrusions of the differential case that rotates at high speed while being immersed in lubricating oil in the differential carrier, or the ring gear that is fixed to the differential case by bolts, thereby reducing the drag of the differential case or the ring gear. The objective is to reduce the coefficient, reduce oil agitation loss, and ultimately increase the transmission efficiency of the differential.

In order to achieve such an objective, the present invention takes the following technical measures.

That is, in a differential in which a ring gear is fixed to a flange formed on the outer periphery of a differential case using a plurality of bolts, at least the outside of the head of the bolt is attached to the support piece fixed using the bolt. That is, you have installed a cover to cover it.

As a result of taking such measures, the appearance of the differential case is smooth with no bolt heads protruding. Experiments have shown that the oil agitation loss caused by the rotation of the differential case has been reduced by almost half compared to conventional models.

Embodiments of the present invention will be specifically described below with reference to the drawings.

Figure 2 shows a so-called front-wheel drive (FF) in which the transverse engine transmission and front wheel differential are integrated.
An example in which the present invention is applied to a differential 2 in a lance axle 1 will be shown. That is, in this transaxle 1, the transmission case 3 and the differential carrier 4 are constructed as an integral container in communication with each other, and the final pinion 6 of the transmission 5 is connected to the final pinion 6 of the transmission 5.
directly meshes with the ring gear 7 of the differential 2 to perform final deceleration. Furthermore, since the differential 2 is located below the transmission 5, almost the entire differential carrier 4 is submerged in shoulder slip oil, as shown in the oil level in FIG.

The basic configuration of the differential 2 is similar to that shown in the previously introduced Japanese Utility Model Application Publication No. 56-72956.

That is, a differential case 12 in which a pair of differential pinions 10 that mesh with left and right differential side gears 9 directly connected to an axle 8 are supported via a differential pinion shaft 11 is rotatably housed and supported within the differential carrier 4, and the differential case 12 is rotatably housed and supported within the differential carrier 4. The ring gear 7 is fixed to the ring gear 12. Furthermore, the attachment of the ring gear 7 to the differential case 12 is as follows:
A plurality of bolt insertion holes 14 are formed at equal intervals in the flange portion 13 integrally formed on the outer periphery of the differential 12, and screw holes 15 corresponding to the bolt insertion holes 14 are formed in the ring gear 7, and threaded through the bolt insertion holes 14. The threaded portion 17 of the inserted bolt 16 is screwed into the threaded hole 15 of the ring gear 7. Therefore, the head 18 of the bolt 16 is shaped to protrude from the side surface of the flange portion 13. In the present invention, the support piece 19 for the cover is
is fixed to the flange portion 13, and a cover 20 that covers at least the outside of the head 18 of the bolt is attached to the support piece 19.

For example, as shown in FIG. 3, the cover support piece 19 may have a donut disk shape having a hole 21 formed to correspond to the bolt insertion hole 14 of the flange portion 13. It can be formed by integrally forming a plurality of tabs 23 on the peripheral edge of the play l-2'2 and folding the tabs so as to stand up. Further, each cover support piece 19 is provided with a screw hole 25 into which a screw 24 for fixing the cover 20 is screwed. As shown in FIG. 4, the plate 22 is attached to the flange 13 by being sandwiched between the flange 13 of the differential case 12 and the head 18 of the bolt 16 inserted through the flange 13. be installed against the

On the other hand, in the illustrated example of the cover 20, as shown in FIG.
TI! It has a smooth curved surface that gradually approaches the outer surface of the differential case 12 toward the top of the differential case 12, and is divided into two for ease of assembly.

This cover 20 can be easily molded from oil-resistant, heat-resistant resin, or the like. Further, as clearly shown in FIG. 4, the lower edge of this cover 20 is formed with an inward flange 26 that engages with the lower edge of the peripheral edge of the plate 22. Furthermore, the height of the portion of the cover 20 located outside the window 27 of the differential case 12 is lowered so as not to obstruct the flow of oil into the differential case 12 through the window 27 when assembled. I'm taking care of it. Furthermore, the support piece 1 for the cover
A screw insertion hole 28 is formed at a position corresponding to the screw hole 25 of 9.

The cover 20 is opened from both sides of the differential case 12 so that the screw holes 28 and the screw holes 25 of the support piece for the cover coincide with each other, and the screws 29 are inserted through the screw holes 28. The above screw hole 25
It can be installed extremely easily by simply screwing it on.

When the cover 20 is attached in this way, the appearance of the body of the differential case 12 becomes bullet-shaped with few protrusions, as shown in FIG. 5, and as a result, the fluid drag coefficient of the differential case is dramatically increased. can be reduced.

Note that the scope of the present invention is of course not limited to the above embodiments. That is, as the cover 20, the fourth
As shown by the imaginary line in the figure, it may be formed so as to cover only the annular space including the head 18 of the bolt 16. Furthermore, as shown in FIG. 6, the present invention can also be applied to a rear differential. In this case as well, similarly to the embodiment shown in FIGS. 2 to 5, the flange W13J of the differential case 12' is used to secure the ring gear 7' to the bolt 16'. A cover 20' is attached to cover the head 18'. As a cover, the head 1 of the bolt 16'
A cover substantially similar to that shown in phantom in FIG. 4, which covers the annular space containing only 8', can be used. Further, in the illustrated example, the cover 20 is formed in two pieces, but it goes without saying that it may be formed as an annular body. Further, although the cover support pieces 19 are formed by bending the ears of a donut disc-shaped member in the illustrated example, separate support pieces may be attached to each bolt 16.

[Brief explanation of drawings]

Figure 1 is a graph showing changes in total loss torque when the input rotation speed in the differential changes;
FIG. 2 is a sectional view showing an embodiment of the invention, FIG. 3 is an exploded perspective view of the main components of the invention, FIG. 4 is an enlarged sectional view of the main parts of the invention, and FIG. 5 6 is an external view of a differential case or ring gear to which the present invention is applied, and FIG. 6 is a sectional view showing another embodiment of the present invention. 2...Differential, 7...Ring gear, 1
2...Differential case, 13...Flange portion, 16...Bolt, 18...(Bolt) head, 19...(Cover) support piece, 20...Cover applicant Daihatsu Representative of Kogyo Co., Ltd. Patent attorney Toyoharu Higuchi and 2 others Figure 1

Claims (1)

[Claims] (11) In a differential in which the ring gear is fixed to the flange formed on the outer periphery of the differential case using a plurality of bolts, at least the outside of the head of the bolt is attached to the support piece fixed using the bolts. A differential characterized by having a cover attached to it.