WO2009031947A1

WO2009031947A1 - Heat exchanger and traction vehicle provided with such a heat exchanger

Info

Publication number: WO2009031947A1
Application number: PCT/SE2007/000779
Authority: WO
Inventors: Sigurd Sonderegger; Magnus Bernhardsson
Original assignee: Volvo Lastvagnar Ab
Priority date: 2007-09-07
Filing date: 2007-09-07
Publication date: 2009-03-12

Abstract

A heat exchanger formed with a channel system for circulating a first fluid therein, and adapted to promote heat transfer between the first fluid and at least one of a second fluid circulated in the channel system and ambient air. The heat exchanger (20) has an upper support surface, and has a structural strength sufficient to support a person standing thereon, and comprises a fitting (30) for mounting the heat exchanger on a traction vehicle enabling a person to stand on the support surface. Such a heat exchanger may be used on several places on a vehicle where a supporting structure is required, for example steps and standing platforms. By using such a structure as a heat exchanger, its surface, used for standing on, will be heated. This may be advantageous, especially in cold climates, where it will help keep the surface free of ice, and thus less slippery.

Description

HEAT EXCHANGER AND TRACTION VEHICLE PROVIDED WITH SUCH A HEAT EXCHANGER

Technical field

The present invention relates to a heat exchanger formed with a channel system for guiding a fluid. The invention also relates to a traction vehicle provided with such a heat exchanger.

Technical background

In heavy traction vehicles, there is an increasing need for cooling capacity. Not only are engines becoming more and more powerful, with increasing demands for cooling, but also liquids such as servo oil, transmission oil, retarder oil, hydraulic oil need cooling. In addition, urea systems may require cooling, as may compressed air systems.

In order to provide increased cooling capacity, it has been suggested to provide one or several heat exchangers in the engine compartment, in addition to the conventional front radiator. Although providing some additional cooling capacity, the engine compartment is generally not optimal for cooling purposes, due to an elevated temperature and limited air circulation.

Summary of the invention

It is therefore an object of the present invention to provide an improved cooling system for a traction vehicle.

A first aspect of the present invention relates to a heat exchanger formed with a channel system for circulating a first fluid therein, and adapted to promote heat transfer between the first fluid and a second fluid circulated in the channel system or between the first fluid and ambient air. The heat exchanger has an upper support surface, and has a structural strength sufficient to support a person standing thereon, and further comprises a fitting for mounting the heat exchanger on a traction vehicle enabling a person to stand on the support surface.

The heat exchanger can thus be used as an access surface, e.g. used for climbing onto the frame, and is preferably adapted to be mounted in a plane essentially parallel to the ground.

Such a heat exchanger may be used on several places on a vehicle, such as a truck, where a supporting structure is required, for example steps and standing platforms. By using such a structure as a heat exchanger, its surface, used for standing on, will be heated. This may be advantageous, especially in cold climates, where it will help keep the surface free of ice, and thus less slippery. Even in places where ice is not a problem, a heated surface will typically be dryer and less slippery.

A heat exchanger according to the invention is advantageous, as it utilizes space and cooling capacity that has previously not been used. The heat exchanger according to the invention may advantageously be combined with more conventional heat exchangers, for example the front radiator and any additional heat exchangers arranged in the engine compartment. One particular structure that is very suitable for use as a heat exchanger is the platform arranged on the frame behind the driver compartment, also known as a catwalk. Such a catwalk is typically quite large, and thus provides excellent surface area as well as metal bulk to provide additional heat transfer. As a cat walk of some sort is typically arranged on most traction vehicles, i.e. a tractor unit of a truck, integration of a heat exchanger in this structure provides for a simple and efficient increase in cooling capacity, without interfering with the general design and functionality of the truck. Its position, behind the driver compartment but in a relatively open space, will allow for excellent air flow around the heat exchanger, especially during driving.

A second aspect of the invention relates to a cooling system, comprising heat exchanger according to the first aspect of the present invention. The channel system of the heat exchanger is connected to a system containing a fluid to be cooled, and a pump is arranged to circulate the fluid through the channel system of said heat exchanger, thereby allowing heat to be transferred from the fluid.

In a typical embodiment, the heat exchanger is adapted to transfer heat from a cooling fluid used for cooling a component, e.g. the engine. The heat may be transferred to the ambient air, much like in the front radiator of the traction vehicle.

The fluid to be cooled is preferably a liquid, which is advantageous when the fluid is used as a cooling fluid, i.e. for transferring heat from a system to be cooled, such as the engine. However, the term "fluid" is intended to include both liquid and gas. Further, the fluid to be cooled is not necessarily a cooling fluid, but may be any fluid which is brought to an elevated temperature for other reasons. One such example is compressed air, which advantageously is cooled to a lower temperature.

The heat exchanger may be adapted to transfer heat from the fluid to be cooled to the ambient, but may alternatively be arranged to transfer heat to another fluid. For example, the heat exchanger may be arranged to transfer heat between a fluid to be cooled and the cooling fluid of the engine cooling system.

A third aspect of the invention relates to a traction vehicle having a frame, a driver compartment in the front end of the frame, and a heat exchanger according to the first aspect of the invention.

The heat exchanger can be fitted on the frame behind the driver compartment, or be arranged to be used as steps for ascending said vehicle.

The vehicle may further comprise a cooling system according to the second aspect of the invention.

Brief description of the drawings

Figure 1 shows a schematic side view of a traction vehicle.

Figure 2 shows a perspective view of the rear part of a traction vehicle, provided with a heat exchanger according to a first embodiment of the invention.

Figure 3 shows a an exploded view of the heat exchanger in figure 4.

Figure 4a-b show two examples of channel systems in a heat exchanger according to the invention.

Figure 5 shows a perspective view of the rear part of a traction vehicle, provided with a heat exchanger according to a second embodiment of the invention.

Figure 6 shows a perspective view of a heat exchanger according to a further embodiment of the invention.

Figures 7a and 7b show schematic block diagrams of two engine cooling systems provided with a heat exchanger according to an embodiment of the present invention.

Figure 8 shows a schematic block diagram of a further cooling system provided with a heat exchanger according to an embodiment of the present invention. Figure 9 shows a schematic block diagram of a further cooling system provided with a heat exchanger according to an embodiment of the present invention. Detailed description of preferred embodiments Figure 1 shows a traction vehicle 1 or tractor unit of the type provided with a fifth wheel 2 for attaching a trailer 3. Such a traction vehicle is also referred to as a "tractor". The tractor generally comprises a frame 4 typically comprising two longitudinal frame members 5.

A front wheel axle 7 and one or more rear wheel axles 8 are mounted to the frame 4. Further, an engine 9 is mounted to the front end of the frame, and a fuel tank 10 is also mounted to the frame, typically between the wheel axles 7, 8 and below the frame 4. A cab 11 is arranged on top of the frame 4, and defines a driver compartment 12, generally above and behind the engine.

Immediately behind the driver compartment 12, in level with the upper surface 4a of the frame 4, an essentially flat panel 14, adapted to support a person climbing on top of the frame, is mounted. The panel 14 is typically made of one or several aluminum profiles. The panel 14 is also referred to as a "catwalk". The catwalk is arranged to allow access by e.g. the driver to the space 15 between the driver compartment 12 and a trailer 3 attached to the tractor. Such access can be required e.g. for coupling/uncoupling connections between the tractor and the trailer.

The catwalk 14 can be arranged between the outer sides of the longitudinal frame members 5, or extend outside the frame, to the entire or part of the full vehicle width. Also, the catwalk can extend between the front axle and first rear axle, or parts of this area. It may comprise several portions, and possibly be modular in its design.

The vehicle also comprises steps 17 leading up to the catwalk, and similar steps 16 providing access to the driver compartment. These steps are similar in design as the catwalk, i.e. typically made of aluminum profiles.

Figure 2 shows in greater detail a part of a tractor 1 , provided with a heat exchanger according to an embodiment of the present invention.

As indicated in figure 2, the heat exchanger is adapted to be used as a "catwalk", i.e. as a support surface on the deck plane of the chassis, for allowing access between the driver compartment and a connected trailer. The heat exchanger should therefore be structurally strong, and provided with a surface that is well adapted for walking on, i.e. non slippery, etc. The heat exchanger 20 illustrated in figure 2-3 is a substantially flat, solid member 21 , and has channels 23, here parallel to each other, extending through the entire member 21 between two opposite sides of the member 21.

The element can be manufactured by molding or by an extruded profile. Different materials can be used for the heat exchanger, but a light metal material, such as aluminum, may be suitable.

In the embodiment in figure 2, also shown in figure 3, the heat exchanger comprises end portions 22, adapted to be fitted to the member 21. The end portions may 22, as indicated in figure 2-3, be solid pieces with internal channels 24, and be fitted on opposite sides of the central portion with suitable means, e.g. welding. As indicated in figure 3, several end portions 22 may be fitted to each side. The channels 24 in each end portion 22 are formed so that it, when fitted to one side of the central member 21 , interconnects at least two channel openings on this side. By fitting at least one end portion on each side, an interconnected channel system of desired form and extension can be formed. Examples of resulting channel systems are given in figure 4a and 4b.

As indicated in figure 3, the heat exchanger 20 may be modular, in order to easily adapt to different sizes of available space. In the illustrated example, the central members 21 (and possibly any end portions 22) may be provided with grooves 25 on one side and a protrusion 26, adapted to be slid into a groove, on the other. Two members 21a, 21 b can now be fitted together, by sliding the protrusion of one portion into the groove of another.

With such a modular heat exchanger, it is possible to adapt the shape and size of the heat exchanger, to more efficiently use the available space on the vehicle frame.

According to another embodiment, illustrated in figure 5, the end portions need not have the same form and structure as the central portion, as was the case in figure 2-3. Instead, the end portions may be as simple as pieces 28 of pipe or tube, each piece secured to the central portion (e.g. by fasteners or welding) so as to connect two channel openings with each other. Alternatively, a continuous tube 29 or pipe is arranged to extend along and inside the channels. Such a tube or pipe will thus extend back and forth in the channels, and have curve portions protruding outside the element to pass from one channel to the next. According to this embodiment, no separate end portions are required. . .

6

As illustrated in figure 5, the heat exchanger is preferably provided with fittings, here in the form of steel brackets 30, to enable mounting of the heat exchanger to the frame 4 of the vehicle.

According to a further embodiment of the invention, illustrated in figure 6, the heat exchanger 20 has channels 23, e.g. in the form of metal tubes, mounted underneath a structurally strong panel 21 , e.g. an aluminum profile. The tubes are mounted in such a way as to promote heat exchange between a fluid in the tube and the material in the panel. This can be achieved e.g. by welding the tube to the panel. Figures 7a, 7b, 8 and 9 show examples of how a heat exchanger 20 according to the present invention can be employed in various situations. It is evident from these figures and the description thereof, that the heat exchanger 20 may be used to transfer heat between a gas and the ambient air, between a liquid and the ambient air as well as between two fluids (gas or liquid).

In figures 7a and 7b, a heat exchanger 38 according to the present invention is arranged to transfer heat between a liquid and the ambient air. In these examples, the heat exchanger 20 is connected to an engine cooling system. A channel system 33 is provided for leading a flow of cooling liquid, typically water, through the engine block 35. The channel system 33 is further connected to a first heat exchanger 36 typically in the form of a front radiator (see figure 1), and a pump 37 is arranged to circulate the cooling liquid through the heat exchanger 36. In use, the cooling liquid is circulated through the engine, where it absorbs heat from the engine thus cooling the engine. The liquid is then pumped to the heat exchanger, where heat is transferred to the ambient air, thus cooling the liquid. The process is continuous during operation of the engine.

The cooling system is further provided with a second heat exchanger 38 according to an embodiment of the present invention. This second heat exchanger contributes to cooling the cooling liquid, thereby improving the cooling capacity of the system.

In a first example, illustrated in figure 7a, the second heat exchanger 38 is connected to engine in series with the first heat exchanger. The pump 37 will thus circulate cooling liquid from the engine, through the first heat exchanger 36, and then through the second heat exchanger 38.

In the second example, illustrated in figure 7b, the second heat exchanger 38 is connected in parallel to the first heat exchanger 36, thus forming a second cooling circuit. In this case, it may be advantageous to arrange a second pump 39 for the second cooling circuit, in order to allow independent control of the circulation flow in each circuit.

This may be useful for example in a situation where it is important to provide warming of the catwalk, to remove ice. The engine cooling system can then be controlled to use the second heat exchanger 38 to a larger extent, for a limited period of time, possibly until the vehicle is put in motion. When the vehicle is in motion, it is quite possible that the front radiator 36 has larger cooling capacity, and it may then be advantageous to have a larger cooling liquid flow through this heat exchanger.

Figure 8 shows a further example of how a heat exchanger 40 according to an embodiment of the present invention can be employed. Here, the heat exchanger is arranged to transfer heat between two liquids, e.g. from a cooling liquid to a liquid to be cooled. In the illustrated example, the heat exchanger is connected to the engine cooling system, in a similar way as indicated in figure 7a. The heat exchanger is further connected to another system 41 , containing a second fluid to be cooled. For example, such a system could be the steering servo system, and the second fluid be the servo oil. In addition to transferring heat from the cooling liquid to the ambient air, the heat exchanger will now transfer heat from the servo oil to the cooling liquid. Other liquids that require cooling are transmission oil, retarder oil, and hydraulic oil.

In this embodiment, the heat exchanger must be provided with two separate channel systems 42, 43 that preferably are arranged to interlace in such a way as to enhance the transfer of heat between liquids in the two systems. As an example, a heat exchanger as indicated in figure 3 may be provided with end elements to connect every other straight channel with each other, so as to form two set of channels as illustrated in figure 4b.

Figure 9 shows yet another example of a cooling system, with a heat exchanger 45 according to an embodiment of the present invention adapted to cool a gas that requires cooling.

In the illustrated example, the heat exchanger is connected to a pneumatic system 46, comprising a compressor 47, a flow control valve 48, and a pressure tank 49. In this case, the pressurized air in the pneumatic system is cooled by transferring heat to the ambient air.

In another example, similar to the embodiment in figure 9, the heat exchanger is connected to a fuel system of the vehicle, and adapted to cool fuel circulating in the system. This is particularly advantageous when using alternative fuels, such as liquid ethanol or pressurized liquid dimethylesther (DME).

The person skilled in the art realizes that the present invention by no means is limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

For example, a heat exchanger according to the invention may obviously be provided with forced ventilation, such as a mechanical fan directed to create an air flow across the heat exchanger surface.

Claims

1. A heat exchanger (20) formed with a channel system for circulating a first fluid therein, and adapted to promote heat transfer between said first fluid and at least one of a second fluid circulated in said channel system and ambient air, c h a r a c t e r i z e d in that said heat exchanger (20) has an upper support surface, and has a structural strength sufficient to support a person standing thereon, and in that said heat exchanger further comprises a fitting (30) for mounting the heat exchanger on a traction vehicle enabling a person to stand on said support surface.

2. A heat exchanger according to claim 1 , wherein the fitting (30) is arranged to mount the heat exchanger in a plane essentially parallel to the ground.

3. A heat exchanger according to claim 1 , comprising a solid member (21 ) adapted to support a person, said member having two opposite sides and a plurality of channels extending between said two opposite sides, and at least one end portion (28) adapted to interconnect at least two channel openings, so as to connect at least two channels to form said channel system.

4. A heat exchanger according to claim 1 , comprising a solid member (21 ) adapted to support a person, said member having two opposite sides and a plurality of channels extending between said two opposite sides, at least one tube (29) arranged inside said channels, and having curved portions extending between channels, thereby forming said channel system.

5. A heat exchanger according to claim 1 , comprising a solid member (21 ) adapted to support a person, and at least one tube forming said channel system, said tube being attached to the underside of said member (21).

6. A cooling system for a traction vehicle, comprising a heat exchanger (38; 40; 45) according to one of the preceding claims, the channel system of said heat exchanger being connected to a system containing a fluid to be cooled, and a pump to circulate said fluid through the channel system of said heat exchanger, thereby allowing heat to be transferred from said fluid.

7. A cooling system according to claim 6, further comprising: a cooling channel system (33) for leading a cooling fluid past a component to be cooled, so as to transfer heat from said component to said cooling fluid, wherein said heat exchanger is connected to said cooling channel system, and said fluid to be cooled is said cooling fluid.

8. A cooling system according to claim 6 or 7, wherein said heat exchanger is adapted to exchange heat between said fluid to be cooled and ambient air.

9. A cooling system according to claim 6 or 7, wherein said heat exchanger is adapted to exchange heat between said fluid to be cooled and a second fluid circulated in said heat exchanger.

10. A cooling system according to one of claims 6-9, wherein said cooling fluid is a liquid.

11. A traction vehicle comprising a heat exchanger according to one of claims 1-5, said heat exchanger being arranged in an essentially horizontal plane, and arranged to support a person.

12. The traction vehicle according to claim 11 , further comprising a frame (4) and a driver compartment (12) in the front end of the frame, and wherein said heat exchanger is fitted to said frame (4) behind said driver compartment.

13. The traction vehicle according to claim 11 , wherein said heat exchanger is arranged to be used as steps (15; 17) for ascending said vehicle.

14. The traction vehicle according to one of claims 11-13, further comprising a cooling system according to one of claims 5-9.