GB2113783A

GB2113783A - Gear unit for a vehicle

Info

Publication number: GB2113783A
Application number: GB08234820A
Authority: GB
Inventors: Eugen Svab
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1982-01-28
Filing date: 1982-12-07
Publication date: 1983-08-10
Also published as: DE3202692C2; DE3202692A1; FR2520311B1; US4502352A; GB2113783B; FR2520311A1

Description

1 GB 2 113 783 A 1

SPECIFICATION Gear unit for a vehicle

The invention relates to a gear unit for a vehicle, and in particular, but not exclusively to a 5 gear unit for a motor vehicle.

A gear unit is known which has a start-up clutch unit in the form of an hydraulic clutch or a hydrokinetic torque converter, a continuously variable contact drive unit and variously arranged epicyclic gear units which are shifted by appropriate forward and reverse- gear clutch units. A gear unit of this type is described in German Patent Specification 16 30 298.

In the Applicants' earlier German Patent Application No. P 31 17 657.7 a gear unit of a type such as this is proposed, involving the arrangement of a reduction gear unit in the form of a planetary gear.

Gear units of this type are at present being intensively developed in the motor car industry since from the point of view of attempts to save fuel a greater degree of gear efficiency is expected from continuously variable contact gear units than can be achieved by conventional automatic gears comprising sets of epicyclic gears which are shifted by an hydraulic servo arrangement.

The gear units for vehicles developed in this field up till now each have the disadvantage, as is evident from the two examples described, that the start-up clutch unit used is in the form of an 95 hydraulic clutch or a hydrokinetic torque converter. These units contribute to a reduction in the over-all efficiency of the gear on account of the slippage which occurs in them.

According to the present invention, there is provided a gear unit for a vehicle, the unit comprising an input shaft adapted to be driven by the driving shaft of a drive motor via an hydraulically controlled one-disk-wet start-up clutch, the input shaft extending coaxially through 105 a primary shaft of a continuously variable contact gear unit, the traction member of which drives a secondary shaft arranged parallel to the primary shaft, and an epicyclic gear unit disposed on the input shaft to drive the primary shaft in different 110 rotational directions via a forward and reversegear clutch unit, the secondary shaft driving, via a reduction gear unit, an output shaft which is in driving connection with a differential gear unit, wherein the housing of the start-up clutch receives an annular piston and simultaneously is adapted to form the flywheel for a driving internal combustion engine, carries a starter gear and drives a hydraulic fluid pump.

As a result of the construction of the start-up 120 chitch unit it is possible to avoid hydraulic slippage losses and to permit a proper arrangement of the oil pump, which makes available the pressure medium for controlling the clutch, the continuously variable contact gear unit actuated 125 by hydraulic servo arrangements and the hydraulically actuated forward and reverse-gear clutch unit.

The forward and reverse-gear clutch may be a cone clutch for connecting or locking together the elements of the epicyclic gear, with the annular gear being locked on to the housing by an hydraulic annular piston in order to engage reverse gear. The planet wheel carrier may be connected to the annular wheel by a restoring spring in order to engage forward gear. Thus no pressure medium is required for the forward and reverse- gear clutch for driving in the forward gear, so that the supply to the oil pump may be reduced and thus its pumping action, which impairs the overall efficiency of the gear, may be reduced.

If the housing of the start-up clutch is formed by pressed sheet metal parts, the oil channels may be constructed integrally in the form of corrugations. Short fluid channels causing little loss are thus made available for the pressure medium required.

The invention is described, by way of example, with reference to the accompanying drawing, in which Figure 1 is a vertical section through a gear unit according to the invention, and Figure 2 is a section along the line 11-11 in Figure 1.

A gear unit for a motor vehicle is illustrated in Figure 1, and is provided with an input shaft 3 which is driven by the driving shaft 1 of a drive motor via a start-up clutch unit 2. The input shaft 3 extends coaxially through a primary shaft 4 of a continuously variable contact gear unit 5 whose traction member 6 drives a secondary shaft 7 arranged parallel to the primary shaft 4. An epicyclic gear unit 8 is disposed at the end of the input shaft 3 opposite the start-up clutch unit. The gear unit 8 can drive the primary shaft 4, which is controlled by a forward and reverse-gear clutch unit 9, in different rotational directions. The secondary shaft 7 driven via the traction member 6 drives, via a reduction gear unit 10, an output shaft 11 which is in driving connection with a differential gear unit 12.

The start-up clutch unit 2 is an hydraulically controlled one-disk-wet clutch which has a clutch housing formed by three pressed sheet metal parts 13, 14 and 15, an outer covering 16, a driving collar 17, a pressure plate 18 secured to part 15 and an annular piston 19 arranged in an annular area between parts 13 and 14 as well as a clutch-disk arrangement disposed in the clutch housing and consisting of a clutch disk 20, a damping device 21 and a collar 22.

The clutch housing forms the flywheel for a driving internal-combustion engine, and a ring gear 23 for engagement by a starter motor pinion is disposed directly on the outer covering 16 of the clutch housing. In addition, a so-called Pitot collector 24, which is required for the hydraulic control of the start-up clutch unit 2, may be disposed on part 15 of the clutch housing. The two cooperating parts 13 and 14 of the clutch housing are preferably constructed in such a way that they form compression-medium channels 25 required for the annular piston 19 in the form of corrugations 26 which are provided in part 13 and 2 GB 2 113 783 A 2 are closed by the other part 14. The two parts 13 and 14 of the clutch housing are advantageously connected together by spot welds 27.

The driving collar 17 of the clutch housing drives the driven gearwheel of a toothed gearwheel oil pump 28 which is arranged in a partition wall 29 of the gear housing. The same components may be used for this oil pump 28 as are already used as a compression-medium pump in the case of conventional automatic gears.

The collar 22 of the clutch-disk arrangement is non-rotatably connected to the input shaft 3, the other end of which is connected to the planet wheel carrier 30 of the epicyclic gear unit 8. The planet wheel carrier 30 has two sets of mutually engaging planet wheels, the inner set 31 of which engages with a sun wheel 32 formed on the primary shaft 4, while the outer set 33 engages with an annular gear 34 which may be locked to the gear housing.

Conical surfaces, which form the forward and reverse-gear clutch unit 9 in connection with an annular piston 5 37 and its restoring spring 38, are provided on a radially outward part of the planet wheel carrier 30, on a component 35 which is connected to the annular gear 34 and which is mounted axially displaceably and rotatably in the gear housing, and on part of the housing 36.

The arrangement of these conical surfaces is such that in order to lock the annular gear 34 in the housing, as is required for engaging reverse gear, the annular piston 37 is hydraulically actuated, whereas in order to connect the planet wheel carrier 30 to the annular gear 34, as is required for engaging forward gear, only the pressure space behind the annular piston 37 need be released, whereupon the restoring spring 38, constructed accordingly, effects this connection. During operation in forward gear, therefore, the forward and reverse-gear clutch unit 9 does not require any compression medium, so that the pumping action performed most of the time the vehicle is running is reduced, which is reflected in an improvement in the overall efficiency of the gear or in reduced fuel consumption.

Claims

1. A gear unit for a vehicle, the unit comprising an input shaft adapted to be driven by the driving shaft of a drive motor via an hydraulically controlled one-disk-wet start-up clutch, the input shaft extending coaxially through a primary shaft of a continuously variable contact gear unit, the traction member of which drives a secondary shaft arranged parallel to the primary shaft, and an epicyclic gear unit disposed on the input shaft to drive the primary shaft in different rotational directions via a forward and reverse-gear clutch unit, the secondary shaft driving, via a reduction gear unit, an output shaft which is in driving connection with a differential gear unit, wherein the housing of the start-up clutch receives an annular piston and simultaneously is adapted to form the flywheel for a driving internalcombustion engine, carries a starter gear and drives a hydraulic fluid pump.

2. A gear unit according to Claim 1, characterized in that the forward and reverse-gear clutch unit is a cone clutch which can connect together the elements of the epicyclic gear, the annular gear being locked to the housing by the clutch by actuating an annular piston in order to engage reverse gear, and the planet wheel carrier being connected to the annular gear by a restoring spring after releasing the annular piston, in order to engage forward gear.

3. A gear unit according to Claim 1 or Claim 2, characterized in that fluid channels for the hydraulic fluid for operating the annular piston of the start-up clutch are constructed integrally in the clutch housing, by corrugations formed in one part which are closed by the other part which is connected to said one part by spot welds.

4. A gear unit substantially as herein described -with reference to the accompanying drawing.

Peinted for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1983. Published by the Patent Office 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.