HEAT EXCHANGE MEANS FOR A VEHICLE

Abstract: Heat exchange means (30, 40) for a vehicle (10) comprising a tank (13) containing a first fluid and a heat exchange element (30) in thermal connect with said first fluid, said heat exchange element (30) comprising a passage (31) wherein a second fluid is passed through said passage (31) in thermal contact with said heat exchange element (30).

Description: Title: Heat Exchange Means For A Vehicle Description of Invention This invention relates to heat exchange means for a vehicle. In vehicles, it is known to provide heat exchange means comprising a fan which draws air through a number of heat exchange stages in which one or more fluids circulate through one or more passages, for example, hydraulic fluid, transmission oil, or water, to cool the fluid. The same means is often used to provide air conditioning. Such an arrangement is bulky, requires a large air flow through the heat exchange stages and consequently a large and/or fast fan. In a hydraulic system, it is desirable that hydraulic fluid be passed through a heat exchange stage to cool the fluid before retrirning to a tank. Conventionally a suitable valve is provided to produce a flow of hydraulic fluid to such a heat exchange stage when the pressure of the hydraulic fluid downstream of the valve exceeds a certain level. Such heat exchange stages may also be inappropriate for some systems, for example hydraulically operated hammers, where the hydraulic system experiences high peak pressures. An object of the invention is to provide a new or improved heat exchange means which reduces or overcomes the above problems. According to a first aspect of the present invention we provide heat exchange means for a vehicle comprising a tank containing a first fluid and a heat exchange element in thermal contact with said first fluid, the heat exchange element comprising a passage wherein a second fluid is passed through said passage in thermal contact with said heat exchange element. The heat exchange element may comprise a plurality of passages, which may be connected to a common inlet and a common outlet. Means may be provided to urge said second fluid through said passage. Where a plurality of passages are provided, a single means to urge said second fluid may be provided to urge the second fluid through all of said passages. The means to urge said second fluid may be activated when the temperature of the first fluid exceeds a first predetermined value and/or when the temperature of the second fluid exceeds a second predetermined value. The means to urge said second fluid may comprise a fan. The first fluid may comprise hydraulic fluid, and the second fluid may comprise air. The second fluid may alternatively comprise water or oil, in which case the means to urge said second fluid may comprise a pump means. According to a second, preferred, aspect of the invention we provide a heat exchange means according to the first aspect of the invention further comprising a further heat exchange element in thermal contact with said first fluid, the further heat exchange element comprising a further passage, wherein a third fluid is passed through said further passage in thermal contact with said further passage. The further heat exchange element may comprise a plurality of passages which may be connected to a common inlet and a common outlet. Further means to urge said third fluid through said further passage may be provided. here a plurality of passages are provided, a single further means to urge said third fluid may be provided to urge the third fluid through all of said further passages. Preferably, the first fluid may comprise hydraulic fluid, the second fluid may comprise air and the third fluid may comprise transmission oil. According to a third aspect of the invention we provide a vehicle comprising a heat exchange means according to the first or second aspect of the invention. Suitable covers may be provided as the common inlet and common outlet for the air passages to prevent the entry of debris into the passages. Where a fan is provided, the fan may be accommodated within a recess provided within the tank. The invention will now be described by way of example with reference to the following drawings wherein Figure 1 is a side view of a vehicle incorporating the present invention Figure 2 is a perspective view of the outside of a fluid-containing tank including a heat exchange means according to the present invention and viewed from the side and rear of the tank Figure 3 is a front end view of the tank of Figure 2 Figure 4 is a rear end view of the tank of Figure 2 Figure 5 is a section on line 5-5 of Figure 3, Figure 6 is a partially cut away section on line 6-6 of Figure 3 Figure 1 discloses an example of a vehicle which is provided with a heat exchange means according to the present invention. In the present example the vehicle 10 comprises material handling implements in the form of a front loader 11 and a back hoe 12, both of which are operable by a respective hydraulic system, although any other vehicle with any other hydraulic system may be provided as desired. The vehicle 10 is provided with a tank 13 to provide a reservoir to contain a first fluid, in the present example hydraulic fluid. The vehicle 10 is further provided with an engine (not shown) and with a pump, also not shown, to provide hydraulic fluid from the tank 13 to the hydraulic systems to operate the material handling implements 11, 12. As shown in Figures 2 to 6, the tank 13 is connected to a part 14 of the vehicle 10, and comprises a front wall 17, a rear wall 18, a first side wall 19, a second side wall 20, an upper wall 21 and a lower wall 22. A filling tube 15 is located in the upper wall 21 and is closed with a cap 16. The tank is further provided with a hydraulic fluid outlet 23 and a hydraulic fluid inlet 24. A first aperture 25 is provided in the front wall 17 and a second aperture 26 is provided in the rear wall 18. A generally cylindrical section 27a is attached to the front wall 17 such that it surrounds the aperture 25 and leads in a direction inwardly of the tank from the aperture 25. The generally cylindrical section 27a is closed with a first support plate 27b. A generally cylindrical section 28 is attached to the rear wall 18 such that it surrounds the aperture 26 and leads in a direction inwardly of the tank from the aperture 26. The generally cylindrical section 28 is closed with a second support plate 29. The tank 13 is provided with a first heat exchange element 30. The first heat exchange element 30 comprises a plurality of passages in the form of tubes 31 extending between the first aperture 25 and the second aperture 26. The tubes at one end are supported by the support plate 27b and at the other end by the support plate 29. The tubes are also supported by intermediate support plates 32, 33. A second fluid is passed through the tubes 31, in the present example air, and a means to urge the air through the tubes 31 is provided by a fan, shown diagrammatically at 34. The fan 34 is disposed within the second aperture 26 to draw air into the aperture 26 and urge it along the tubes 31 to be expelled at the first aperture 25. The tubes 31 are not in flow communication with the interior of the tank 13. The tubes 31 are disposed such that they are below the normal operating level of the hydraulic fluid contained within the tank. In the present example, the tubes 31 have a diameter of 15mm although any appropriate size may be used as desired. Suitable baffles or covers may be provided to prevent debris or foreign bodies being drawn into the apertures 25 or 26 . Also disposed within the tank 13 towards the floor 22 is a further heat exchange element 40. The further heat exchange element 40 comprises a transmission oil inlet 41 and a transmission oil outlet 42 by which means a third fluid, in the present example transmission oil can be passed through the heat exchange element 40. The heat exchange element 40 comprises a pair of parallel transverse end parts 43a, 43b connected between which are a plurality of passages in the form of longitudinal tubes 44 in thermal contact with the fluid contained within the tank 13. Means may be provided (not shown) to urge the transmission oil through the tubes 44, and may comprise for example a conventional pump. Temperature detection means may be provided at the hydraulic fluid outlet 23 and/or the transmission outlet 42. The fan 34 may be activated when the transmission oil or hydraulic oil is detected as having exceeded a respective predetermined temperature. In operation, when the vehicle engine and/or hydraulic systems are being operated, the temperature of the transmission fluid and the hydraulic fluid respectively will increase. So long as the temperature of the transmission oil and hydraulic fluid remain below their respective predetermined temperature, then the fan 34 will not be activated. If the temperature of the transmission oil is detected to have exceeded its predetermined temperature, then the fan 34 will be activated to cool the hydraulic fluid by drawing air through the tubes 31. The cooled hydraulic fluid will hence act to cool the transmission oil passing through the further heat exchange element 40. The fan 34 may be deactivated when the temperature of the transmission oil has fallen below the said predetermined temperature. Similarly, when the temperature of the hydraulic fluid has been detected as exceeding its predetermined temperature, as a result of heat being dissipated in the hydraulic fluid from the transmission oil and/or the hydraulic system being operated, the fan 34 will again be activated to draw air through the tubes 31 and thus cool the hydraulic fluid. The fan 34 may be deactivated once the temperature of the hydraulic fluid has fallen below its predetermined temperature. When the engine and/or the hydraulic systems are being operated, the heat exchange means will reach an equilibrium temperature, depending on the heat being generated in the transmission oil and/or the hydraulic fluid. The fan 34 effectively acts to maintain a desired equilibrium temperature. Since the walls 17, 18, 19, 20, 21 and 22 of the tank are in thermal contact with the hydraulic fluid, there will be a certain rate of loss of heat from the hydraulic fluid through the tank walls. It may well be that if the heat generated in the hydraulic fluid during operation or transmitted from the transmission oil is sufficiently small, transmission of heat through the walls of the tank will be sufficient to cool the hydraulic fluid without the fan being activated. This may particularly be the case when, for example, the vehicle is being driven relatively short distances along a road. It will be apparent that either heat exchange element could be used in isolation. Providing a heat exchange element to cool the hydraulic fluid alone is desirable in that it overcomes the problems associated with known means of cooling the hydraulic system. Providing a heat exchange means to cool transmission oil by dissipating heat in the hydraulic tank is similarly desirable since it removes a heat exchange stage from in front of the main radiator of the engine. Most preferably, however both elements are used as shown in the present example such that the temperature throughout the hydraulic systems and vehicle transmission reaches a desired equilibrium temperature. The removal of the hydraulic fluid and transmission oil heat exchange stages from their conventional position under the bonnet, where they are cooled by the main fan of the vehicle which also draws air through the radiator and air conditioning heat exchanger, is desirable. By reducing the number of stages through which the main vehicle fan is acquired to draw air, the fan itself may be made smaller and/or slower, with a consequent reduction in noise and an increase in energy efficiency. The efficiency of the vehicle air conditioning may be improved. Reducing the number of stages also provides certain design advantages such as reducing the amount of equipment required to be accommodated under the vehicle bonnet. In the present example, the volume of the tank is approximately half the volume of the entire hydraulic system and therefore when the machine hydraulic systems are operated the hydraulic fluid effectively remains in the tank for only a short period after entry before being extracted from the tank again. This removes any need for stirring means to ensure that heat is dissipated throughout the hydraulic fluid. The locating of the further heat exchange means towards the base of the tank is advantageous in that, even if the hydraulic systems are not being used, convection currents set up by local heating of the hydraulic fluid will distribute heat throughout the hydraulic fluid. It will be apparent that the techniques of dissipating heat in a volume of liquid held in a tank and/or cooling of the liquid in that tank may be adapted for use with any other vehicle system or fluid, for example water, as may be appropriate. The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims: CLAIMS: 1. Heat exchange means for a vehicle comprising a tank containing a first fluid and a heat exchange element in thermal connect with said first fluid, said heat exchange element comprising a passage wherein a second fluid is passed through said passage in thermal contact with said heat exchange element. 2. A heat exchange means according to claim 1 wherein the heat exchange element comprises a plurality of passages. 3. A heat exchange means according to claim 2 wherein said passages are connected to a common inlet and a common outlet. 4. A heat exchange means according to any one of the preceding claims wherein means are provided to urge said second fluid through said passage. 5. A heat exchange means according to claim 4 where dependent on claim 3 wherein a single means to urge said second fluid may be provided to urge the second fluid through all of said passages. 6. A heat exchange means according to claim 4 or claim 5 wherein the means to urge said second fluid may be activated when the temperature of the first fluid exceeds a first predetermined value and/or when the temperature of the second fluid exceeds a second predetermined value. 7. A heat exchange means according to any one of claims 4 to 6 wherein the means to urge said second fluid comprise a fan. 8. A heat exchange means according to any one of the preceding claims wherein the second fluid comprises air. 9. A heat exchange means according to any one of claims 1 to 6 wherein the second fluid comprises water or oil. 10. A heat exchange means according to any one of the preceding claims wherein the first fluid comprises hydraulic oil. 11. A heat exchange means according to any one of claims 1 to 7 comprising a further heat exchange element in thermal contact with said first fluid, said further heat exchange element comprising a further passage wherein a third fluid is passed through said further passage in thermal contact with said further heat exchange element. 12. A heat exchange means according to claim 11 wherein the further heat exchange element comprises a plurality of further passages. 13. A heat exchange means according to claim 12 wherein the further passages are connected to a common inlet and a common outlet. 14. A heat exchange means according to any one of claims 11 to 13 wherein further means to urge said third fluid through said further passage are provided. 15. A heat exchange means according to claim 14 where dependent on claim 13 wherein a single further means to. urge said third fluid is provided to urge the third fluid through all of said passages. 16. A heat exchange means according to any one of claims 11 to 15 wherein the first fluid comprises hydraulic fluid, the second fluid comprises air and the third fluid comprises transmission oil. 17. A heat exchange means as described herein with reference to the accompanying drawings. 18. A vehicle comprising a heat exchange means according to any one of the preceding claims. 19. A vehicle as described herein with reference to the accompanying drawings. 20. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.

Inventors: DUNCAN ROBERT, DUNCAN, ROBERT
Applicants: BAMFORD EXCAVATORS LTD, DUNCAN ROBERT, DUNCAN, ROBERT, J C BAMFORD EXCAVATORS LIMITED
Application year: 1999
Main classification: F28D1
IPC codes: F01M5, F28D1, F28D15