JPH0451245Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention relates to a lubrication structure for a center differential installed in a four-wheel drive vehicle that can switch between a four-wheel drive state and a two-wheel drive state.

[Conventional technology]

In four-wheel drive vehicles, a so-called center differential (hereinafter referred to simply as a differential) is used to avoid braking phenomena during turns and to achieve neutral steering to improve steering performance. ) is provided. This center differential is functionally equivalent to a front differential or a rear differential, and first transmits the rotational output from the transmission to the differential case, and also has a pair of side gears that simultaneously mesh with a pinion that is rotatably supported by the trunnion shaft of this differential case. One of them (front wheel drive differential side gear) is connected to the front wheel drive system, and the other (rear wheel drive differential side gear) is connected to the rear wheel drive system. This center differential distributes driving force to the front wheels and rear wheels so that the rotation speed of the differential case becomes the average rotation speed of the front wheels and the average rotation speed of the rear wheels. As a result, while transmitting driving force from all wheels to the road surface, it is possible to absorb the difference in rotational speed between the front and rear wheels during a turn and avoid braking phenomena. Furthermore, since the driving force can be appropriately distributed to all wheels, steering performance can be improved by approaching neutral steering. Furthermore, recently, even though it is a four-wheel drive vehicle with a center differential as described above, it can be changed to a four-wheel drive state (hereinafter simply referred to as a four-wheel drive state) or a two-wheel drive state (hereinafter simply referred to as a two-wheel drive state) as necessary. Four-wheel drive vehicles that are configured to be able to selectively switch between the two are also being proposed. For example, when switching between a 2WD state in which only the rear wheels are driven and a 4WD state in which all four wheels are driven, 2WD/4WD switching allows the front wheel drive differential side gear of the center differential to be connected to and removed from the front wheel drive system. In addition to the mechanism, there is a differential function state (center differential free state) in which the differential case and the front wheel drive differential side gear can rotate relative to each other, and a differential non-functional state (center differential free state) in which relative rotation between the differential case and the front wheel drive differential side gear is prevented. A center differential/free switching mechanism is added to switch between the center differential and the differential lock state. The above-mentioned center differential lock/free switching mechanism has, for example, a spline formed on the outer periphery of the differential case, and a spline wheel that rotates integrally with one of the side gears adjacent to the spline in the axial direction. In addition, a switching sleeve is fitted that can be switched between a differential lock position where the splines and the spline wheel are fitted at the same time, and a differential free position where the differential case is fitted only with the splines. If the switching sleeve is simultaneously fitted to the splines of the differential case and the spline wheel integrated with one of the side gears, preventing relative rotation between the differential case and the side gears, the pinion meshing with this side gear will not be able to rotate. The side gear rotates integrally with the differential case. Note that the switching sleeve described above is switched and moved, for example, by a shift fork supported by a shift fork shaft that slides on an axis parallel to the axis of the center differential.

[Problem that the invention attempts to solve]

Inside the differential case of the center differential above,
A pinion rotatably supported by a trunnion shaft is installed in such a way that it meshes with a pair of side gears at the same time, and since these pinions and side gears rotate at a fairly high speed while meshing with each other, inside the differential case, Sufficient lubricant must be circulated. Conventionally, lubricating oil has been introduced into the differential case by simply drilling a through hole in the differential case, and it has not always been possible for external lubricating oil to circulate sufficiently into the differential case. Because centrifugal force acts on the lubricating oil adhering to the differential ace,
This is because the lubricating oil cannot flow from the outside to the inside of the differential case. This invention was conceived under the above circumstances, and its object is to introduce sufficient lubricating oil into the differential case with a simple structure.

[Means to solve the problem]

In order to solve the above problem, this invention takes the following technical measures. That is, it includes a differential case that rotates integrally with the output shaft of the transmission, a pinion that is rotatably supported by the trunnion shaft of the differential case, and first and second side gears that mesh with the pinion simultaneously, and the outer periphery of the differential case. A spline wheel is formed adjacent to the spline of the differential case, and a spline wheel that rotates integrally with one of the side gears is provided adjacent to the spline of the differential case.
This spline is fitted with a switching sleeve that moves back and forth between a differential lock position where it fits on both of the spline wheels and a differential free position where it fits only with the splines of the differential case, and this switching sleeve is attached to the shift hawk shaft. In a center differential configured to be reciprocated by a supported shift hawk, a through hole is provided in the differential case, and
An oil scraping protrusion is formed on the outer surface of the differential case at a position rearward in the rotational direction of the differential case with respect to the through hole, while an oil scraping protrusion is formed on the shift hawk at a position radially outward of the differential case through a slight gap with respect to the oil scraping protrusion. An integrally extending oil guide wall is formed that overlaps with the main body.

[Effect]

A differential case with an oil-scavenging protrusion rotates inside the oil-guiding wall provided on the stationary shift hawk. When the oil scraping protrusion passes inside the oil guide wall, the lubricating oil immediately in front of the oil scraping protrusion is prevented from moving radially outward of the differential case by the oil guide wall. Therefore, it is forcibly pushed into the differential case through the through hole formed on the outer surface of the differential case in front of the scraping protrusion.

【effect】

The oil scooping protrusion formed on the rear side of the through hole passes through the stationary oil guide wall, forcing lubricating oil to be introduced into the differential case from the through hole in the differential case, causing the differential case to rotate. Sufficient lubricant will circulate within the differential case as long as the Moreover, in this invention, the oil-scraping protrusion is integrally formed on the differential case, and the oil-guiding wall is integrally formed on the shift fork, so the number of parts does not increase at all, and therefore there is almost no increase in cost. It's fleeting.

[Explanation of Examples]

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 3 is a sectional view of a transfer 1 equipped with a center differential to which the present invention is applied. The transfer 1 includes an engine (not shown),
These are attached following the transmission. The output shaft 2 that introduces the output of the transmission into the transfer 1 has a
A differential case 4 of a center differential 3 is supported so as not to be relatively rotatable. Inside the differential case 4, a pinion 6 rotatably supported on the trunnion shaft 5 is provided.
and a first side gear 7 and a second side gear 8 that mesh with the pinion 6 at the same time. The first side gear 7 is fixed to the front end of a rear wheel output shaft 9 which is coaxially rotatably supported behind the output shaft 2, and the second side gear 8 is fixed to the outer periphery of this rear wheel output shaft 9. is supported for relative rotation.
Then, a spline wheel 11 having the same diameter as the spline 10 on the outer periphery of the differential case 4 is integrally arranged in parallel with the second side gear 8, and there is a space between the spline 10 of the differential case 4 and the spline wheel 11. A differential/free switching sleeve 12 is provided which can reciprocate between a differential free position where it engages only the splines 10 of the differential case 4 and a differential position where it engages both the splines 10 of the differential case and the spline wheel 11. This switching sleeve 12 and the shift hawk shaft 2 supported by the transfer case 19
The shift fork 21 supported by the center differential lock free switching mechanism is configured to be driven reciprocatingly by the shift fork 21 supported at zero. Adjacent to the rear of the spline wheel 11 on the rear wheel output shaft 9, a front wheel drive gear 14 to which a spline wheel 13 having the same diameter as the spline wheel 11 is integrally attached is supported for relative rotation. On the other hand, a front wheel output shaft 15 is rotatably supported on the side of the rear wheel output shaft 9 in parallel with the rear wheel output shaft 9. A chain 17 is connected between an output gear 16 fixed to the rear wheel output shaft 15 and the front wheel drive gear 14. By rotating the front wheel drive gear 14, the front wheel output shaft 1 rotates.
5. In addition, the spline wheel 11 and the spline wheel 13
Between both spline wheels 11, 1
A 2WD/4WD switching sleeve 18 that can reciprocate between a 4WD position where it engages with the spline 3 and a 2WD position where it engages with only the spline 11 is slidably fitted therein. This 2WD/4WD switching sleeve 18
constitutes a two-wheel drive/four-wheel drive switching mechanism, which is driven by a shift fork that is reciprocated by an actuator (not shown). In 4WD mode, as shown in Figure 3,
The two-wheel drive/four-wheel drive switching sleeve 18 assumes a position where it engages with both the spline wheel 11 and the spline wheel 13, and the switching sleeve 12 of the center differential/free switching mechanism
assumes a center differential free position in which it engages only with the splines 10 of the differential case 4. In this state, the output is transmitted from the first side gear 7 of the center differential to the rear wheel output shaft 9, and the second side gear 8 is transmitted to the pair of spline wheels 11, 13, the front wheel drive gear 14, and the chain 17. Output is transmitted to the front wheel output shaft 15 via the front wheel output shaft 15. on the other hand,
In the 2WD state, the above 2WD/4WD switching sleeve 1
8 assumes a position where it engages only with the spline wheel 11, and the switching sleeve 12 of the center differential lock/free switching mechanism assumes a center differential position where it engages with both the spline 10 of the differential case and the spline wheel 11.
In this state, the power transmission from the second side gear 8 to the front wheel drive system is cut off, and the differential case 4, the first side gear 7, and the second side gear 8 are rotated together, and this rotation is the same as that of the first side gear. The signal is transmitted from the side gear to the rear wheel output shaft 9. In the two-wheel drive/four-wheel drive switching transfer with a dental differential configured as described above, the differential lubrication structure of the present invention is configured as follows. That is, as shown in detail in FIGS. 1 and 2, the trunnion shaft 5 on the outer periphery of the differential case 4
Appropriate number of through holes 23 are provided in the more forward position.
An oil scraping protrusion 24 that protrudes outward in the radial direction is provided at a portion of the outer periphery of the differential case adjacent to the rear side of the through hole 23 in the rotational direction of the differential case. It is preferable that the peripheral surface 24a of this oil scraping projection 24 is formed into a cylindrical surface concentric with the rotation center of the center differential 3, and that a rake surface 24b is formed on the front surface in the rotation direction. Then, the appropriate part of the shift fork 21 that engages with the switching sleeve 12 is held partially forward while engaging with the splines 10 of the differential case 4 to take the center differential free position. The cylindrical circumferential surface 2 of the oil scraping projection 24 is integrally extended to the inner surface of the extension portion 21a.
An oil guiding wall 25 having a cylindrical inner surface shape is formed which overlaps 4a with a slight gap therebetween. Next, the operation of the above-mentioned differential lubrication structure will be explained. Even if the differential case 4 rotates, the shift hawk 21
is stationary with respect to the transfer case 19. As shown in FIG. 2, when the oil scooping protrusion 24 of the differential case 4 passes inside the shift fork 21, the lubricating oil present in front of the rake surface 24b of the protrusion 24 is transferred to the differential case by the oil guiding wall 25. Since the escape route to the outside in the radial direction is blocked, it is forcibly pushed into the interior of the differential case 4 through the through hole 23. Every time the oil scooping projection 24 passes inside the oil guide wall 25, lubricating oil from outside the differential case is sent into the differential case 4 by the pumping action as described above, so the differential case 4 rotates. During this time, sufficient lubricating oil will always be circulating in the differential case. The oil scraping protrusion is integrally formed when the differential case 4 is cast. Further, the oil guide wall 25 to be integrally formed with the shift fork 21 can also be formed when the shift fork 21 is cast. Therefore, the present invention can be easily implemented without adding any particular number of parts, and there is almost no increase in cost. Of course, the scope of this invention is not limited to the embodiments described above. For example, the specific shape of the differential case can be modified in various ways.

[Brief explanation of the drawing]

Figure 1 shows the main parts of the present invention, and Figure 4 -
2 is a sectional view taken along the - line in FIG. 1; FIG. 3 is a sectional view of a transfer equipped with a center differential to which the present invention is applied; Figure 4 is - of Figure 3.
FIG. 2... Output shaft, 3... Center differential, 4... Differential case, 5...
Trunnion shaft, 6... Pinion, 7... First side gear, 8... Second side gear, 10... Spline, 11... Spline wheel, 12...
...Switching sleeve, 20...Shift hawk shaft, 21...Shift hawk, 23...Through hole, 2
4... Protrusion, 25... Oil guiding wall.

Claims (1)

[Claims for Utility Model Registration] A differential case that rotates integrally with the output shaft of the transmission, a pinion rotatably supported by the trunnion shaft of the differential case,
A spline wheel is provided on the outer periphery of the differential case, and a spline wheel that rotates integrally with one of the side gears is connected to the spline of the differential case. is provided adjacent to the spline of the differential case, and reciprocates between a differential lock position where the spline fits on both the spline and the spline wheel, and a differential free position where it fits only with the spline of the differential case. In a center differential configured to fit a moving switching sleeve and to move the switching sleeve back and forth by a shift fork supported by a shift fork shaft, In addition to providing a through hole, an oil scraping protrusion is formed on the outer surface of the differential case at a position rearward in the rotational direction of the differential case with respect to the through hole. A lubrication structure for a center differential characterized by integrally extending an oil guiding wall that overlaps radially outward of the differential case through a slight gap.