Heat systems for vehicles

A vehicle having an operators enclosure and an hydraulic circuit is provided with a heat exchanger to warm the enclosure. The heat exchanger is supplied with fluid from the return side of the hydraulic circuit thus eliminating the conventional engine coolant pipes.

The invention relates to vehicles and in particular to centre pivot steered 
vehicles equipped with a hydraulic unit, such as wheel loaders, etcetera, 
in which the driving unit is situated on one part of the chassis and a 
heatable driver's cab and working equipment on the other part. 
In known vehicles of this kind it is usual for the heating unit in the 
driver's cab to be driven by the cooling water of the engine. This, 
however, necessitates the use of tubes or hoses and joints to convey the 
cooling water from the driving unit situated on one part of the chassis to 
the driver's cab situated on the other part. These pipes are relatively 
long, which leads to loss of heat and also hinders the work of the pivot 
joint inserted between the two parts of the chassis, quite apart from the 
fact that the pipes are subjected to a particularly strong mechanical 
stress when the vehicle is running and are therefore easily damaged. 
It is an object of the present invention to obviate or mitigate the above 
disadvantages. 
According to the present invention there is provided a vehicle having a 
prime mover, an hydraulic circuit supplied with oil from a pump driven by 
the prime mover, and an operators enclosure including a heat exchanger, 
said heat exchanger being supplied with fluid from said hydraulic circuit. 
Preferably said heat exchanger is supplied with fluid by pipes connected in 
parallel with a low pressure zone of said hydraulic circuit. 
Preferably also said vehicle is provided with a chassis formed in two parts 
and connected by a joint for pivotal movement about a vertical axis, said 
engine being located on one of said parts and said operators enclosure 
being located on another of said parts. 
Preferably also the connection between the heat exchanger pipes and the low 
pressure region includes a variable control device for varying the flow 
through the heat exchanger.

The vehicle comprises a front part 1 of the chassis and a rear part 2, both 
of which are connected by a pivot joint 3 lying about midway between the 
axles. On part 1 of the chassis is the driver's cab 4 with the working 
equipment, the shovel 5 and the operational elements necessary thereto. On 
the rear part 2 of the chassis is the engine 6 with the radiator 7 and the 
structural parts appertaining to the drive. In the driver's cab there is a 
heating unit 8, which can be varied between fully on or fully off 
according to the time of year. 
As can be seen from FIG. 2 (the circuit diagram), a hydraulic oil pump 9 is 
connected with the engine 6 and supplies fluid to either a control device 
12 or an oil collecting tank 13 by pipes 10 and 11. By means of the 
control device 12 a hydraulic cylinder 14 is controlled from the driver's 
cab 4 to operate the loading mechanism 5. 
The hydraulic oil, which becomes heated up when the vehicle is working, is 
cooled down in an oil cooler 15. 
The heat exchanger belonging to the heating unit 8 is connected by pipes 
16, 16a and a regulating device 17 in parallel with a return pipe 18 
leading from the control device 12 to the oil tank 13. By means of the 
regulating device 17 the hot hydraulic oil can be conveyed through the 
heat exchanger in the heating unit 8 and thus used as working fluid in the 
heating unit. The regulating device 17 which may be a valve of any 
suitable form to allow variable flow through the pipes 16, 16a can be 
operated to vary the flow, or alternatively to stop the influx of the 
hydraulic oil to the heating unit 8. 
As can be seen, the hydraulic oil pipes run directly below the floor of the 
driver's cab 4, so that there is no difficulty in leading branches 
thereform to the heating unit 8.