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Title:
CONVECTOR SYSTEM WITH LIQUID FLOW CONTROL
Document Type and Number:
WIPO Patent Application WO/2015/105453
Kind Code:
A1
Abstract:
A convector system (2) for a vehicle, comprising a pipeline (4) provided with an inlet (6) and an outlet (8) and configured to convey a heat transfer liquid which delivers heat via heat delivery units (10) in the vehicle, which system comprises a valve unit (16) situated on the pipeline (4). The convector system (2) comprises a control unit (18) configured to generate a valve control signal (20) for regulating said valve unit (16), and to receive at least one input signal (22) containing information about heat demand in the vehicle. The regulation is conducted on the basis of said input signal (22) and a set of regulating criteria. The valve unit (16) comprises at least two on/off valves (24, 26) and is controlled by said valve control signal (20) in such a way that no flow, a smaller flow or a larger flow of the heat transfer liquid will pass through the valve unit (16). The regulating criteria comprise at least two threshold values for heat demand, in the form of a first threshold value T1 greater than zero and a second threshold value T2 which is higher than the first threshold value T1, and the regulating criteria comprise. - the control unit (18) being configured to generate a valve control signal (20) such that a small flow passes through the valve unit (16) if the heat demand is above said first threshold value T1 but below said second threshold value T2, and - the control unit (18) being configured to generate a valve control signal (20) such that a larger flow passes through the valve unit (16) if the heat demand is above said second threshold value T2.

Inventors:
PETTERSSON JONNY (SE)
Application Number:
PCT/SE2015/050001
Publication Date:
July 16, 2015
Filing Date:
January 08, 2015
Export Citation:
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Assignee:
SCANIA CV AB (SE)
International Classes:
B60H1/00
Foreign References:
GB1578643A1980-11-05
US5299631A1994-04-05
US20040103861A12004-06-03
US6471137B12002-10-29
US20070144191A12007-06-28
Attorney, Agent or Firm:
AHLING, Annika (Södertälje, SE)
Download PDF:
Claims:
Claims

1 . A convector system (2) for a vehicle, comprising a pipeline (4) provided with an inlet (6) and an outlet (8) and configured to convey a heat transfer liquid which delivers heat via heat delivery units (10) in the vehicle, which system comprises a valve unit (16) situated on the pipeline (4),

c h a r a c t e r i s e d in that the convector system (2) comprises a control unit (18) configured to generate a valve control signal (20) for regulating said valve unit (16), and to receive at least one input signal (22) containing information about heat demand in the vehicle, that said regulation is conducted on the basis of said input signal (22) and a set of regulating criteria and that said valve unit (16) comprises at least two on/off valves (24, 26) and is controlled by said valve control signal (20) in such a way that no flow, a smaller flow or a larger flow of the heat transfer liquid will pass through the valve unit (16),

which regulating criteria are based on at least two threshold values for heat demand, comprising a threshold value T1 greater than zero and a second threshold value T2 which is higher than the first threshold value T1 , and the regulating criteria comprise

- the control unit (18) being configured to generate a valve control signal (20) such that a smaller flow passes through the valve unit (16) if the heat demand is above said first threshold value T1 but below said second threshold value T2, and

- the control unit (18) being configured to generate a valve control signal (20) such that a larger flow passes through the valve unit (16) if the heat demand is above said second threshold value T2. 2. The convector system according to claim 1 , in which said valve unit

(16) comprises a first on/off valve (24) and a second on/off valve (26) such that when the second on/off valve (26) is open it allows a flow which represents a predetermined smaller portion of the flow which is possible through the first on/off valve when it is open.

3. The convector system according to claim 1 , in which said valve unit

(16) comprises a first on/off valve (24) and a second on/off valve (26) such that the first on/off valve allows said larger flow when it is open, and said second on/off valve (26) allows said smaller flow when it is open and the first on/off valve (24) is closed. 4. The convector system according to any one of claims 1 -3, in which said smaller flow is less than 25% of said larger flow.

5. The convector system according to claim 5, in which said smaller flow is 5-15% of said larger flow.

6. The convector system according to any one of claims 2-5, in which the valve control signal (20) is configured to regulate the first on/off valve in such a way that the latter is open for a variable portion of a recurring activation period with a predetermined duration, e.g. 10 seconds.

7. The convector system according to claim 6, in which the length of time of the variable portion depends directly on the heat demand.

8. The convector system according to any one of the foregoing claims, in which said larger flow is within the range 10-20 litres/minute, e.g. 15 l/min.

9. The convector system according to any one of the foregoing claims such that the convector system (2) is configured to be supplied via a feed line (12) connected to the system's inlet (6), the pipeline's outlet (8) is connected to a return line (14), said inlet (6) and outlet (8) are situated close together and the pipeline from the inlet to the outlet forms a loop such that the inflow section of the pipeline runs parallel with the outflow section of the pipeline.

Description:
Title

CONVECTOR SYSTEM WITH LIQUID FLOW CONTROL

Field of the invention

The present invention relates to a convector system according to the preamble of the independent claim.

Background to the invention

A convector system is a warming system which may for example be used in a vehicle, e.g. a bus. A number of heat delivery units such as radiators, convectors, fans etc. will be provided on board, e.g. along the vehicle's walls by the passenger seats and close to the doors. The system's heat delivery is often regulated on the basis of input signals from temperature sensors inside and outside the vehicle. The specifications mentioned below refer to examples of various heating systems.

EP-2214922 refers to a heating and/or cooling system for vehicles which comprises a number of separate circuits with heat exchangers for distributing heat to different parts of the vehicle. The flow to each circuit is regulated by a valve, and a circulation pump is provided in the common circuit to create a flow of the heat medium.

EP-1354734 describes a warming system for vehicles which comprises separate circuits to different consumer units which are supplied by a common pump.

DE-19824516 describes a heating system in which each of a number of separate warming circuits is provided with a pump.

A conventional convector system for a vehicle usually comprises a pipeline with an inlet and an outlet. The pipeline is adapted to conveying a heat transfer liquid, e.g. water, which delivers heat via heat delivery units situated close to the pipeline. In one variant of the conventional system a valve is provided on the pipeline in the form of an on/off valve which is either completely open or completely closed.

When heat is needed, the valve opens for a predetermined portion of a 10 second period. If the heat demand is small, the valve will for example open for two seconds and be closed for eight seconds. If the heat requirement is large, the valve may open for the whole 10 second period, followed immediately by a further 10 second period. The amount of warm water entering the pipeline is thus regulated by the valve's opening time. The pipeline will also be provided with a circulation pump which pumps the water round in order to achieve a uniform temperature. The pump runs as long as heat is needed, i.e. even when the valve is closed during the 10 second periods.

A disadvantage of the convector system described is that the circulation pump will have a short service life, need regular servicing and consume electricity.

The object of the invention is to propose an improved convector system which has a longer service life and therefore needs less servicing, consumes less electricity and is less expensive than today's systems. Summary of the invention

The above objects are achieved with the invention defined by the independent claim.

Preferred embodiments are defined by the dependent claims.

What is here concerned is thus a convector system for a vehicle. The system comprises a pipeline provided with an inlet and an outlet and configured to convey a heat transfer liquid which delivers heat via heat delivery units in the vehicle. The system comprises a valve unit situated on the pipeline, and a control unit configured to generate a valve control signal for regulating the valve unit. The control unit is configured to receive at least one input signal containing information about the demand for heat in the vehicle, and regulation is conducted on the basis of said input signal and a set of regulating criteria. The valve unit comprises at least two on/off valves and is controlled by said valve control signal in such a way that no flow, a smaller flow or a larger flow of the heat transfer liquid will pass through the valve unit. The regulating criteria comprise at least two threshold values for heat demand, in the form of a first threshold value T1 is greater than zero and a second threshold value T2 which is higher than the first threshold value T1 , and the regulating criteria comprise the control unit being configured to generate a valve control signal such that

- a smaller flow will pass through the valve unit if the heat demand is above said first threshold value T1 but below said second threshold value T2, and

- a larger flow will pass through the valve unit if the heat demand is above said second threshold value T2.

When the system calls for heat in the convector system, the valve unit will thus open to allow a small flow which is preferably 5-15% of the possible total flow when it is fully open. This flow is intended to maintain a uniform temperature in the circuit. When the system calls for more heat than can be supplied, the valve unit will be regulated to allow a larger flow. The convector system according to the invention is more cost-effective than today's systems partly because the circulation pump currently used is replaced by an on/off valve which needs less maintenance, i.e. few after-sales problems, and is less expensive. In an advantageous embodiment the inlet and outlet are situated close to one another, making it possible for the convector system's pipe layout to be altered and thereby contributing to more efficient heat delivery and a more uniform temperature. Brief description of drawings

Figure 1 is a schematic block diagram illustrating the convector system according to the present invention. Figure 2 is a schematic diagram of a valve unit according to an embodiment of the invention.

Figure 3 depicts graphs illustrating various aspects of the present invention. Detailed description of preferred embodiments of the invention

The convector system will now be described in more detail with reference to Figures 1 and 2, in which the same reference notations are used throughout for the same or similar parts. Figure 1 is a schematic block diagram of a convector system 2 for a vehicle, e.g. a bus, truck or car.

The convector system comprises a pipeline 4 with an inlet 6 and an outlet 8. The system is configured to be supplied via a feed line 12 which is connected to the system's inlet 6, and the pipeline's outlet 8 is connected to a return line 14. The feed line is connected to the vehicle's combustion engine in a conventional way to enable a heat transfer liquid to be warmed by the heat generated by the engine or some other heat source 13. The feed line is provided with a circulation pump 15. The flow of liquid in the pipeline will generally be of the order of 10-20

litres/minute, e.g. 15 l/min.

The pipeline 4 is configured to convey the heat transfer liquid in such a way as to deliver heat via heat delivery units 10 such as radiators, convectors, fans etc. provided on board the vehicle, e.g. along its walls by the passenger seats and close to the doors.

The convector system further comprises a valve unit 16 situated on the pipeline 4, and a control unit 18 configured to generate a valve control signal 20 for regulating the valve unit.

The control unit 18 is configured to receive at least one input signal 22 containing information about the heat demand in the vehicle, the regulation of which is based on the input signal 22 and a set of regulating criteria. The heat demand is for example determined on the basis of temperature measurements inside and/or outside the vehicle. Said valve unit 16 comprises at least two on/off valves 24, 26 and is controlled by the valve control signal 20 in such a way that no flow, a smaller flow or a larger flow of the heat transfer liquid will pass through the valve unit.

The regulating criteria comprise at least two threshold values for heat demand, in the form of a first threshold value T1 greater than zero and a second threshold value T2 which is higher than the first threshold value T1 , and the regulating criteria comprise the control unit 18 being configured to generate a valve control signal 20 such that

- a smaller flow will pass through the valve unit if the heat demand is above said first threshold value T1 but below said second threshold value T2, and

- a larger flow will pass through the valve unit if the heat demand is above said second threshold value T2.

In one embodiment the valve unit 16 comprises a first on/off valve 24 and a second on/off valve 26 (see Figure 2). The pipeline section in which the second on/off valve is situated runs parallel with the pipeline in which the first on/off valve is situated. The pipeline section with the second on/off valve thus serves as a bypass for the first on/off valve.

The flow allowed by the second on/off valve 26 when it is open represents a predetermined smaller portion of the flow which is possible through the first on/off valve 24 when it is open. The first on/off valve 24 further allows said larger flow when it is open and said second on/off valve 26 allows said smaller flow when it is open and the first on/off valve is closed. The smaller flow is preferably less than 25%, most preferably within the range 5-15%, of the larger flow. In one embodiment the larger flow is within the range 10-20 litres/minute, e.g. 15 l/min. The valve control signal 20 is configured to regulate the first on/off valve 24 in such a way that the latter will open for a variable portion of a recurring activation period A with a predetermined duration, e.g. 10 seconds. The length of time of the variable portion will depend directly on the heat demand. The graph in Figure 3 illustrates the state of the first on/off valve 24 in just three activation periods Ai , A 2 and A 3 .

In one embodiment the inlet 6 and the outlet 8 are close together, which does for example make it possible for them to be situated in a connection unit for connection to the feed line and the return line. The pipeline from the inlet to the outlet also forms a loop such that the inflow section of the pipeline, i.e. the section from the inlet 6 to a turnaround point 28, runs parallel with the outflow section, i.e. the section from the turnaround point to the outlet 8.

The inlet and outlet being close together simplifies the circuitry and makes more efficient heat delivery possible than with previous systems in which the return line was connected to the pipeline nearer to the end point in order to prevent the circulation pump from pumping out warm water.

The regulation will now be described in detail with reference to the graphs in Figure 3. The top graph represents the heat demand H. The y-axis denotes the temperature T and the x-axis the time t. The threshold values Ti and T 2 and a number of points in time trt appear in the graphs. The middle graph represents the state of the first on/off valve 24 and the bottom graph the state of the second on/off valve 26. In both graphs O means valve open and C means valve closed.

In the initial situation when the heat demand H is below the first threshold value T1 , both of the valves will be closed, i.e. in state C. At time ti the heat demand becomes greater than T1 and the second on/off valve 26 opens, i.e. there is a certain heat requirement which can be met by the limited flow allowed by the second on/off valve.

The heat demand increases and at time t 2 the flow of heat transfer liquid is insufficient to provide desired heat, i.e. H is above T2, so the first on/off valve 24 also opens. The variable portion of the activation period A will thus depend on the level of heat demand. The graphs show how the length of the variable portion of A increases for Ai , A 2 and A 3 .

At time t 3 the heat demand reverts to below T2 and the first on/off valve 24 closes. At time t the second on/off valve 26 also closes, since the heat requirement will now be low.

The present invention is not restricted to the preferred embodiments described above. Sundry alternatives, modifications and equivalents may be used. The above embodiments are therefore not to be regarded as limiting the invention's protective scope which is defined by the attached claims.




 
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