GB2330562A

GB2330562A - Vehicle power takeoff unit

Info

Publication number: GB2330562A
Application number: GB9722164A
Authority: GB
Inventors: Alan Ainsworth; Benjamin Martin
Original assignee: Drum Engineering Co Ltd
Current assignee: Gardner Denver UK Ltd
Priority date: 1997-10-22
Filing date: 1997-10-22
Publication date: 1999-04-28
Also published as: GB9722164D0

Abstract

A power takeoff unit is provided comprising a main input shaft 11, a main output shaft 12, auxiliary output means 22 and a transfer device 14. The transfer device 14 is moveable between a first position in which the main input shaft 11 is drivingly connected to the main output shaft 12 and a second position in which the main input shaft 11 is drivingly connected to the auxiliary output means 22. The invention enables a simple compact unit to be provided and when fitted to a vehicle, vehicle engine power can be transferred from vehicle wheels to auxiliary equipment such as an alternator or a compressor, by the simple movement of a single component.

Description

POWER TAKEOFF UNITS The invention relates to driveline power takeoff units.

Driveline power takeoff units are already known, for example for use with road vehicles fitted with an alternator and/or compressor. The compressor may for example be used when the vehicle is stationary to drive auxiliary equipment, for example at roadworks, and the alternator may, for example, be used to provide lighting for the roadworks.

Existing driveline power takeoff units operate by disengaging a drive to the vehicle wheels, then re-engaging this drive with one or more intermediate drive shafts, and finally operating the, or each, intermediate drive shaft to drive an alternator, compressor, or pump.

The existing driveline power takeoff units have a large number of components and take up a relatively large amount of space.

The invention provides a power takeoff unit comprising a main input shaft, a main output shaft, auxiliary output means and a transfer device, the transfer device being moveable between a first position in which the main input shaft is drivingly connected to the main output shaft and a second position in which the main input shaft is drivingly connected to the auxiliary output means.

We have appreciated that this enables a simple and compact unit to be provided, and engine power can be transferred from the vehicle wheels to auxiliary equipment such as an alternator or compressor, by the simple movement of a single component.

The transfer device may be arrangeable to connect the main input shaft to the main output shaft by means of splines.

The main input shaft and main output shaft may for example be coaxial, having external splines, the transfer device comprising an internally splined collar which, in the first position, bridges the ends of the main input and output shafts.

The transfer device may be arrangeable for connection to the auxiliary output means by means of connection with a rotatable component co-axial and concentric with the main input shaft, this component being connected to the auxiliary output means, for example by means of a toothed drive belt or drive chain.

The transfer device may be connectable to the intermediate component by means of external splines on the transfer device which engage with internal splines on the intermediate component.

The auxiliary output means is preferably permanently drivingly connected to an alternator and/or compressor.

The auxiliary output means may be close coupled to an alternator and/or compressor without the use of intermediate drive shafts.

When the alternator is not required, the alternator may be switched to open circuit.

When the compressor is not required, an unloading mechanism may be arranged to come into operation such that there is no air circulation within the compressor.

The invention includes a vehicle fitted with a power takeoff device as defined above.

By way of example, a specific embodiment of the invention will now be described, with reference to the accompanying drawings, in which Figure 1 is a cross-sectional view through an embodiment of power takeoff device according to the invention; and Figure 2 is a perspective view of auxiliary output means of the power takeoff device.

The power takeoff unit shown in Figure 1 comprises a housing 10 and various associated components which in use will be mounted on a vehicle.

There is a main input shaft 11 which in use will be driven by the engine of the vehicle. Co-axial with this input shaft there is a main output shaft 12 which in use will be connected to the road wheels of the vehicle, for example, through a differential.

Each of these shafts has external splines 13. During normal operation of the vehicle, these splines are drivingly interconnected by means of a transfer device in the form of an internally splined collar 14.

Movement of the collar 14 is controlled by a transfer fork 15 and normally the transfer fork 15 is biased to the right, as viewed in Figure 1, by means of an external compression spring device 16 which acts between the casing and a link 17 connected to the transfer fork 15. In this position the collar bridges the ends of the shafts 11 and 12 so that the vehicle engine can drive the vehicle wheels.

In the position shown in Figure 1 however, the transfer fork 15 and collar 14 have been moved to the left by means of a control cable 18 acting on the link 17.

In this position, external splines 19 on the collar 14 engage with internal splines 20 on an intermediate component 21. This component 21 is mounted co-axially around the shaft 11 and when the collar 14 is in the right hand position, in which the road wheels of the vehicle are driven, the component 21 free wheels around the shaft 11.

In the position shown in Figure 1, the drive from the shaft 11 is transmitted to the component 21 via the collar 14 and so the component 21 rotates with the shaft 11. In this position, it drives an auxiliary output member 22 to which it is connected by a toothed drive belt 23. In an alternative embodiment a drive chain may be used.

As shown in Figure 2, the auxiliary output member 22 comprises a wheel 22 having radially projecting lugs. This fits between the shaft 24a of an alternator 24 and the shaft 25a of an air compressor 25. These shafts have axially projecting lugs so the auxiliary output member 22 is permanently coupled directly to the alternator 24 and air compressor 25.

The member 22 may be of resilient material such as rubber to accommodate any slight misalignment between shafts 24a and 25a.

Thus, once a vehicle fitted with the unit has been driven to, for example, the site of roadworks, and the vehicle is stationary, power can be disconnected from the road wheels and directly applied to the alternator and compressor by means of a single operation. If the vehicle engine is then started, the alternator and compressor can be driven.

In many applications, both the alternator and the compressor will be required. The compressor may for example be used to drive road working equipment while the alternator is used to provide lighting. If however the alternator is not required, then it can be placed on open circuit. If the compressor is not required, an unloading mechanism within the compressor may be utilised to ensure that there is no air circulation.

Not only does the unit shown in Figure 1 considerably simplify operation compared to know power takeoff units, but it also eliminates intermediate components such as intermediate drive shafts so the unit is a simpler construction and takes up considerably less space.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS 1. A power takeoff unit comprising a main input shaft, a main output shaft, auxiliary output means and a transfer device, the transfer device being moveable between a first position in which the main input shaft is drivingly connected to the main output shaft and a second position in which the main input shaft is drivingly connected to the auxiliary output means.
2. A power takeoff unit as claimed in Claim 1, in which the transfer device is arrangeable to connect the main input shaft to the main output shaft by means of splines.
3. A power takeoff unit as claimed in Claim 2, in which the main input shaft and main output shaft are co-axial, having external splines, the transfer device comprising an internally splined collar which, in the first position, bridges the ends of the main input and output shafts.
4. A power takeoff unit as claimed in any one of the preceding claims, in which the transfer device is arrangeable for connection to the auxiliary output means by means of connection with a rotatable component co-axial and concentric with the main input shaft, this component being connected to the auxiliary output means,
5. A power takeoff unit as claimed in Claim 4, in which the rotatable component is connected to the auxiliary output means by means of a toothed drive belt or a drive chain.
6. A power takeoff unit as claimed in any one of the preceding claims, in which the transfer device is connectable to the intermediate component by means of external splines on the transfer device which engage with internal splines on the intermediate component.
7. A power takeoff unit as claimed in any one of the preceding claims, in which the auxiliary output means is permanently drivingly connected to an alternator and/or compressor.
8. A power takeoff unit as claimed in Claim 7, in which the auxiliary output means is close coupled to an alternator and/or compressor without the use of intermediate drive shafts.
9. A power takeoff unit constructed and arranged substantially as herein described, with reference to the accompanying drawings.
10. A vehicle when fitted with a power takeoff unit as claimed in any one of the preceding claims.