Electrically driven vehicles

An electrically driven motor vehicle having an electric motor 31 arranged to drive the vehicle through a transmission system 29, 33 and a battery pack 22 to provide power for driving the electrical motor 31, the battery pack being provided with a charging unit 25, 26 including an internal combustion engine 26 and the battery pack 22 and the charging unit 25, 26 being mounted on the vehicle as a unit so as to be readily detachable therefrom to enable it to be replaced at suitable servicing establishments.

This invention relates to electrically driven motor vehicles of the kind 
having a rechargeable battery pack which is arranged to supply electrical 
power to drive the vehicle, through an appropriate transmission system. 
In known vehicles of this kind it has been possible to recharge the 
batteries by means of a charging unit which runs on liquid fuel or other 
power source which is not the battery pack itself. Such a battery charging 
unit is bulky and therefore there have been several proposals for 
accommodating it, including mounting it in a trailer towed by the vehicle. 
Within the practical limits set by the motor vehicle size, the space 
occupied by a battery pack and its charging unit must be kept to a 
reasonable minimum. It has furthermore been found that the provision of a 
battery pack without a charging unit severely limits the range of possible 
use of the vehicle between charging sessions, during which the vehicle is, 
perforce, stationary and it is for this reason that a charging unit may be 
provided. Without incurring a substantial penalty in terms of occupation 
of space as well as of weight, such a charging unit would not, under most 
circumstances, do more than retard the rate of discharge of the batteries 
of the battery pack. 
Another alternative which has been tried is to provide a battery pack and 
electric motor arranged to be driven therefrom and also an internal 
combustion engine. In this construction, the electric drive is used for 
acceleration and also possibly for deceleration but when cruising at 
steady speeds the internal combustion engine is used, preferably at its 
most efficient speed of operation. However, such a vehicle is greatly 
complicated by the need for complex controls and dual transmission 
provision. 
The object of this invention is to provide a motor vehicle with a battery 
pack and a charging unit in a convenient form which will provide a 
practical range of use of the vehicle. 
According to the invention there is provided an electrically driven motor 
vehicle including an electric motor arranged to drive the vehicle through 
a transmission system, a battery pack arranged to provide power for 
driving the electric motor, and a charging unit for charging the battery 
pack, and characterised in that the battery pack and charging unit are 
mounted on a common structure which is provided with means whereby it is 
detachably carried on the vehicle. 
Conveniently, the structure on which the battery pack and charging unit are 
mounted includes a frame which is, at least in part, hollow to provide a 
storage space for fuel for the charging unit. 
According to a further aspect the invention resides in a battery pack and 
charging unit for an electrically driven motor vehicle, characterised in 
that a common structure is provided for supporting the battery pack and 
the charging unit, the structure being provided with means whereby it can 
be detachably secured to a vehicle.

The type of vehicle shown in the drawings is a light goods carrying vehicle 
having a driver's cab portion indicated generally at 10 having side access 
doors 12 and a goods carrying area indicated generally at 11. This has 
rear access doors (not shown). 
A floor indicated at 13 extends through the vehicle, this being supported 
on chassis members 14. A pair of front steerable wheels 15 and a pair of 
driven rear wheels 16 are provided. The vehicle body is of conventional 
kind and would normally be provided with an internal combustion engine 
mounted ahead of the driving compartment, and connected with the rear 
wheels 16 through a conventional transmission system. However, the vehicle 
is electrically propelled as will be described. 
Referring particularly to FIGS. 1 and 2 the electrical drive apparatus is 
shown therein to include a rectangular frame 17. This is mounted on the 
underside of the vehicle, below the floor 13, being attached to 
appropriate fixing brackets by quickly releasable fastenings indicated at 
18, 19 and 21, the former two being at the sides and the latter being at 
the front of the frame 17. Each fastening preferably includes a single 
screw and there is included means for ensuring registration of the holes 
through which the bolt passes to secure the frame 17 in position. 
Contained within and secured to the frame 17 so as to be detachable as a 
complete unit are a plurality of batteries 22. These are arranged in rows 
with fore and aft extending spacers 23. In this example there are twenty 
12 volt batteries 22. 
The frame 17 also houses, ahead of the batteries 22 a charging unit 
comprising an internal combustion engine 26 and an electrical generator or 
dynamo 25. An electrical control device is also provided on this assembly 
and electrical connections to the batteries 22 are shown generally at 27. 
The frame 17 has hollow box section members forming its two longitudinal 
parallel sides, which form storage tanks for fuel for the internal 
combustion engine 26 of the charging unit. Fuel supply pipes are indicated 
at 28 from these tanks to the engine 26. 
The whole assembly of frame 17, batteries 22 and charging unit 25 and 26 is 
therefore detachable as a unit from the vehicle. 
Also mounted on the chassis of the vehicle, behind the battery and charging 
unit assembly is a transmission system 29 for driving the rear wheels and 
a propulsion electric motor 31 to which the batteries supply power through 
a cable indicated generally at 32. Between the motor 31 and the 
transmission 29 is a coupling or drive connection 33. A driver operated 
electrical control unit 34 is also shown fitted at the front of the 
vehicle. 
In the FIG. 3 construction it is envisaged that the vehicle is of the kind 
originally fitted with an internal combustion engine and conventional 
drive to the rear wheels. The vehicle is however modified by removal of 
these components which are replaced by a complete unit which has attached 
to it the necessary equipment for electrical drive instead of internal 
combustion engine drive for the vehicle. 
Beneath the floor of the vehicle a frame 35 is secured to the chassis or 
body of the vehicle by a number of fastening elements indicated at 36. 
These may include bolted fastenings or other types of fixing. This frame 
35 defines three rectangular openings comprising a large central opening 
and two smaller openings at the ends of the frame, which are thus disposed 
at the front and rear of the vehicle respectively. 
The opening in the portion of the frame 35 at the front of the vehicle 
contains electrical control equipment indicated generally at 37. In this 
example, the control equipment is housed in two separate units and it is 
driver operated. 
The opening at the rear of the frame 35 contains an electrical drive motor 
38 which is controlled through the control units 37 by the driver. The 
electric motor 38 drives the rear wheels 16 through a transmission system 
including a differential 39 and intermediate coupling or drive connection 
mechanism indicated generally at 41 which includes a step-down drive. 
The central opening in the frame 35 contains a detachable assembly. This 
assembly comprises a rectangular frame 42 in which are secured a plurality 
of batteries 43. The batteries are arranged in rows with fore and aft 
extending spacers 44. As in the FIGS. 1 and 2 example, there are twenty 12 
volt batteries. Electrical connection from the batteries to the electric 
motor 38 is indicated at 45, comprising a connecting lead on the assembly, 
having a plug engageable in a socket in the vehicle. 
The frame 42 also houses, ahead of the batteries 43 a charging unit. This 
comprises an internal combustion engine indicated generally at 46. This is 
coupled to a dynamo 47. An electrical control for the charging unit is 
also provided on the assembly. 
The frame 42 has hollow box section members along its two parallel 
longitudinally extending sides. These members form storage tanks for 
liquid fuel for running the internal combustion engine 46 of the charging 
unit, as in the FIGS. 1 and 2 construction. Fuel supply pipes are 
indicated at 48. 
The whole of the assembly including the battery pack and the charging unit 
are detachably mounted within the main frame 35. Detachable fastening 
elements between the frame 42 and the frame 35 are indicated at 49. These 
are preferably of the quickly releasable type referred to in the 
equivalent positions in FIGS. 1 and 2. 
In use, the vehicle is driven by the electric motor 38 under driver 
control, the motor being supplied with electrical power from the battery 
pack which comprises the batteries 43. 
The charging unit may be operated if required. Generally, on a relatively 
long journey, the battery pack would be continuously charged by the 
charging unit. This has the effect of retarding the discharge rate of the 
battery pack or maintaining the state of charge thereof. The charging unit 
would not generally be of a size to provide the battery pack with a rate 
of charge greatly in excess of normal requirements. The arrangement 
greatly increases the practical range of such a vehicle as compared with a 
vehicle fitted only with a battery pack and without any charging unit. 
It is intended in use that the battery pack and charging unit assembly may 
be exchanged at suitable servicing establishments either for another 
similar unit or for a battery pack having no charging unit but having the 
same overall dimensions and a fixing arrangement as the assembly shown in 
the drawings. If a vehicle is intended for short journeys, the battery 
pack is used and this is charged when the vehicle is not in use or 
exchanged for another charged battery pack but if the vehicle is to be 
used on longer journeys, the battery pack and charging unit assembly is 
used. 
Though shown fitted in a goods carrying vehicle the battery pack and 
charging unit assembly can be used in other forms of vehicle including 
passenger carrying private motor vehicles.