GB2186332A

GB2186332A - Power transfer apparatus

Info

Publication number: GB2186332A
Application number: GB08630865A
Authority: GB
Inventors: Kap Soo Lee
Original assignee: Kia Motors Corp
Current assignee: Kia Corp
Priority date: 1985-12-26
Filing date: 1986-12-24
Publication date: 1987-08-12
Anticipated expiration: 2006-12-24
Also published as: IN167647B; GB8630865D0; GB2186332B

Abstract

A control arrangement for four wheel drive vehicles has respective shift forks (6, 9) controlling drive to two different vehicle axles so as to give two or four wheel drive at high or low speeds. Both shift forks are actuated by a single common transfer cam (10) rotatable about a gear shaft (2). The shift forks (6, 9) are preferably slidably mounted on respective shift rods (2, 3). On shift fork (6) is preferably actuated by engagement of a (15) in a cam slot (16) of the cam and the other fork (9) by a guide surface (17) of the cam. <IMAGE>

Description

SPECIFICATION Power Transfer Apparatus The present invention relates to a power transfer apparatus of four wheel drive automobiles, in particular to transfer or distribute power to front and rear wheels.

Generally in a fourwheel drive automobile with front and rear wheel drive a power transfer apparatus, mounted in a transmission case, distributes power to the front and rear wheels and has a system that controls the transmission ratio for high and low speed. The conventional power transfer apparatus converts the speed ratio by an operation of a shift lever connected to a hand lever and transfers the power to the front and rear wheels via a hub, sleeve and gears. Thus the above power transfer apparatus is complicated in its structure and its operation is also difficult.

In accordance with the invention, a power transfer apparatus for a four wheel drive automobile, comprises two sleeves which are axially shiftable by respective ones of first and second shift forks carried by respective shift rods, to bring gears into and out of mesh for changing the drive between high and low speeds and between two and four wheel drives; wherein both shift forks are shifted by a common transfer cam which is pivotable between, and locatable in, different drive positions.

This apparatus is thus capable of converting between high and low speeds and distributing the power to two or four of the front and rear wheels, by a single cam.

In the accompanying drawings:- Figure 1 is a diagrammatic sectional view showing the operation of an apparatus in accordance with this invention; Figures 2 to 5 are eniarged views similar two part of Figure 1 but showing different drive positions; and Figure 6 is an axial view of the apparatus.

As shown in Figures 1 and 2 an apparatus in accordance with this invention has a first shift rod 2 to control the operation of one pair of wheels and a second shift rod 3 to control the operation of another pair of wheels, in a transmission case 1.

These shift rods 2, 3 are mounted parallel to each other.

The first shift rod 2 is connected to a first transfer shaft 4 for the transmission of power in known manner by a first sleeve Sand a first shift fork 6. The second shift rod 3 is connected to a second transfer shaft 7 for the transmission of power by a second sleeve 8 and a second shift fork 9. Between the first shift rod 2 and the second shift rod 3 is positioned a transfer cam 10. The transfer cam 10 is connected to the first shift fork 6 so that the latter is slidable in the axial direction of the first shift rod 2 and to the second shift fork 9 so that the latter is slidable together with a shift arm 11 in the axial direction of the second shift rod 3 between first and second compression springs 12, 13.

The first shift fork 6 cooperates with the transfer cam 10 by means of a pin 15, which is carried between legs 14 of the fork and follows a cam slot in the cam 10. The second shift fork 9 and the transfer cam 10 cooperate by means of a roller 18 mounted on the shift arm and following a cam surface 17 of the transfer cam 10. The opposite end of the transfer cam 10 has series of detents 21 which receive a ball 20, loaded by a spring 19, to locate the transfer cam 10 in a selected angular position. The transfer cam 10 is pivoted between its various angular positions by means of a gear shaft 22 which is connected to a hand lever 23 mounted on the gear shaft 22.

Figures 2 to 5 show the various operating positions of the transfer cam 10 and the first and second shift fork 6,9. Figure 2 shows when twowheel drive is operated at high speed. Figure 3 shows when four-wheel drive is operated at high speed, Figure 4 shows when four-wheel drive is operated at low speed, Figure 5 shows when fourwheel drive is in a neutral position.

As shown in Figures 2 to 5, the first shift rod 2 and second shift rod 3 mounted in the transmission case 1 are coupled with the first shift fork 6 and second shift fork 9 so as to be slidable in the axial direction.

The first and second shift forks 6, 9 are moved by means of the transfer cam 10 operated by the hand lever 23.

As shown in Figures 2 and 6 at two-wheel high speed drive, the hand lever 23 is operated to pivot the transfer cam 10 to the position in which the ball 20 engages the iowest detent 21.

The first shift fork 6 is thus moved to cause the first sleeve 5, which slides in the direction of arrow H in Figure 1, to engage a high gear 24. The roller 18, mounted on the shift arm 11, is positioned above the guide surface 17 of the transfer cam 10.

Therefore, a second sleeve 8, coupled to the second shift fork 9, does not engage high and low speed gears 24', 25' between which it is disposed.

When four-wheel drive is then operated at high speed, i.e. to move from the two-wheel high speed drive to the four-wheel high speed drive, the following happens. As shown in Figure 3, when the pin 15 of the first shift fork 6 is moved by rotation of the transfer cam 10, it is to be highest position of the slot 16. The ball 20 is moved to the next detent 21 so as to support the transfer cam 10. The roller 18, connected to the shift arm 11, is also positioned on the highest position of the cam surface 17.

Therefore the first shift fork 6 and the second shift fork 9 cause engagement of the high speed gears 24, 24' located at the top and bottom of the transmission case 1. More specifically, when compared with the above two-wheel high speed drive showed in Figure 2, the first sleeve 5 is not moved in the same manner. The second sleeve 8 is engaged with the high speed gear 24' on the second transfer shaft 7 and moved from the central part of the shaft 7 to the high speed gear 24' by means of the second shift fork 9.

By reference to Figure 4, when the four-wheel drive is to be operated at low speed, the gear shaft 22 is operated so that the transfer cam 10 is moved to let the first and second sleeves 5,8 connected to the first and second shift forks 6, 9 slide in the direction of the arrow L in Figure 1. The first shift fork 6 and the second shift fork 9, connected to the shift cam 11, are moved as seen in Figure 4. The first and second shift forks 6,9 then engage each of the low speed gears 25,25'.

Figure 5 shows a view when the four-wheel drive is operated in a neutral position. The first and second sleeves 5,8', connected to the first and second shift forks 6,9, are not engaged with the high and low speed gears 24,24', 25,25'. Thus the' first and second sleeves 5, 8 are in the neutral position.

When the transmission of an automobile is to be disposed in two-wheel high speed drive, four-wheel high and low speeds drive, or the neutral position, it can be operated by a small force by means of the transfer cam 10 which is manipulated by the hand lever 23. Furthermore, the slot 16, cam surface 17, and detents 21 are easily formed so that the cam controls the first shift fork 6 and the shift arm 11 connected with the second shift fork 9.

The second shift rod 3 moves with the second shift fork 9 and shift arm 11, by virtue of the springs 12, 13. The power transfer operation is thus provided for the four transfer positions by means of the one transfer cam 10.

Claims

1. A power transfer apparatus for a four-wheel drive automobile, the apparatus comprising two sleeves which are axially shiftable by respective ones of first and second shift forks carried by respective shift rods, to bring gears into and out of mesh for changing the drive between high and low speeds and between two and four wheel drives; wherein both shift forks are shifted by a common transfer cam which is pivotable between, and locatable in, different drive positions.

2. Apparatus according to claim 1, wherein the first shift fork has a pin which follows a slot in the transfer cam.

3. Apparatus according to claim 1 or claim 2, wherein the second shift fork and a shift arm carrying a roller, which follows a cam surface of the transfer cam, are disposed between two compression springs on the respective shift rod.

4. Apparatus according to any one of the preceding claims, wherein the transfer cam is located in the different drive positions by a spring loaded ball engaging in one of a plurality of detents in the transfer cam.

5. Apparatus according to any one of the preceding claims, wherein the transfer cam is pivoted by a gear shaft meshing with the cam.

6. A power transfer apparatus, substantially as described with reference to the accompanying drawings.

7. An automobile fitted with a power transfer apparatus according to any one of the preceding claims.