PROPORTIONAL VALVE, COOLING CIRCUIT AND THE MOTOR VEHICLE USING IT

Abstract

A proportional valve (8) has a housing (14) with several ports (15, 16, 17) and a rotor (19) which is rotatably mounted in the housing (14) about an axis (18) in order to vary the flow cross-section between at least two of the ports (15, 16, 17). An optical data reading device (21) has a detection area (22) through which a circumferential region of the rotor (19) can be rotated. Code values, readable by the data reading device (21) and representative of a rotation angle of the rotor (19), are applied to the circumferential region.

Description

[0001] The present invention relates to a proportional valve, a cooling circuit and a motor vehicle that uses such a proportional valve.

[0002] In a circuit where a liquid or gaseous medium circulates, the simplest way to control the mass flow rate is often by switching a pump that drives the circulation on and off. However, as soon as such a circuit has branches, and the mass flow rate in each branch needs to be controlled, this is no longer possible with the pump alone. To control the distribution of a medium flow to different branches of a circuit, so-called proportional valves are used. These allow the free cross-section of a pipe in which the medium circulates to be varied continuously or with high resolution. To precisely control such a proportional valve, it is necessary to know the position of a rotor that determines the free cross-section.

[0003] From EP 1 688 605 B1 a proportional valve is known in which the rotor includes an inductor and an induction sensor arranged adjacent to the inductor is provided for detecting the rotor position.

[0004] One object of the present invention is to provide a proportional valve in which the detection of the rotor position is based on an alternative technique that is insensitive to external magnetic fields.

[0005] According to one aspect of the invention, the problem is solved by providing an optical data reading device in a proportional valve with a housing having several ports and a rotor which is rotatably mounted in the housing about an axis in order to vary a through-cross-section between at least two of the ports, and by providing code values ​​representative of a rotation angle of the rotor that can be read by the data reading device on a circumferential area of ​​the rotor which can be rotated through a detection area of ​​the data reading device.

[0006] In order to be able to read a large number of different code values ​​- and to achieve a correspondingly high angular resolution - the detection area should be elongated in the direction of the axis.

[0007] A laser scanner is particularly suitable for reading such a detection area.

[0008] The invention further relates to a cooling circuit in which the proportional valve described above is arranged to divide a coolant flow between a heat exchanger and a bypass parallel to the heat exchanger. Precise knowledge of the rotor position is necessary here to avoid temperature fluctuations that could impair the function of a device cooled by the cooling circuit.

[0009] A fuel cell is a particularly suitable heat source. If it is charged with compressed air, an intercooler can also serve as a heat source.

[0010] The operating temperature of a fuel cell is significantly higher than the ambient temperature; its operating power can vary considerably, and the heat exchanger must be adequately sized for full-load operation. If the heat exchanger is an ambient air-cooled radiator, its cooling capacity can significantly exceed the fuel cell's heat output, especially when the fuel cell is operating at low load. Therefore, if the entire coolant flow is routed through the heat exchanger, the fuel cell would cool down or not even reach its operating temperature. For this reason, it is advantageous to be able to bypass at least some of the coolant around the heat exchanger when the fuel cell's cooling requirements are low.

[0011] The cooling circuit can also be used to supply a passenger compartment heater.

[0012] A further object of the invention is a motor vehicle with a proportional valve or a cooling circuit as described above.

[0013] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figure. The figure shows: Fig. 1 schematically depicts a cooling circuit of a motor vehicle with a fuel cell power unit; and Fig. 2 a proportional valve of the cooling circuit on a vehicle

[0014] The in Fig. The cooling circuit shown in Figure 1 runs in two parallel branches through a stack of fuel cells 1 and a charge air cooler 2, in which fresh air heated during compression in a compressor (not shown) is cooled down to a temperature suitable for supplying the fuel cells 1. The target operating temperature of the fuel cell 1 is approximately 80°C. Accordingly, during continuous operation, the cooling water temperatures at outlets 3 and 4 of the fuel cells 1 and the charge air cooler 2 are similar.

[0015] Via a common pipe section 5, the cooling water flows from the fuel cells 1 and the charge air cooler 2 first reach a branch 6, through which hot cooling water can be diverted to a passenger compartment heater 7 if required.

[0016] Following branch 6 is a proportional valve 8 with two outlets. One of the outlets is directly connected to the inlet of a pump 10 via a bypass 9; a line branch 11 extends from the other outlet, leading to the pump 10 via a heat exchanger 12. The heat exchanger 12 is a radiator cooler of a known design, with a grid- or meandering-shaped pipe system through which the cooling water flows and which is circulated by ambient air, driven by airflow or, if necessary, a fan.

[0017] The heat exchanger 12 is designed to maintain the fuel cells 1 at their target temperature even at maximum power output; however, this results in such a low cooling water temperature at its outlet at low power output that if this cooling water were supplied directly to the fuel cells 1 at a high flow rate, they would cool down below their target temperature or, if at all, reach their target temperature very slowly when the vehicle was started. Supplying this cold cooling water at a reduced flow rate would create temperature gradients within the fuel cell stack 1, which are also undesirable. By mixing cooling water flows from the heat exchanger 12 and the bypass 9 at the pump 10, a higher cooling water temperature is achieved at the pump 10 outlet than at the heat exchanger 12 outlet.By using the current power output of the fuel cells 1 and temperatures measured at suitable points in the cooling circuit to determine the ratio in which the proportional valve 8 divides the cooling water between the bypass 9 and the heat exchanger 12, the temperature of the cooling water reaching the fuel cells can be controlled according to demand, and temperature deviations resulting from any heat loss to the passenger compartment heating 7 can also be compensated for.

[0018] To avoid “slippages” in the temperature of the cooling water supplied to the fuel cells 1, especially when a user switches the passenger compartment heating on or off and the cooling water temperature at the inlet of the pump 10 suddenly changes, the control unit 13 must have exact, hysteresis-free data about the current position of the proportional valve 8 available in order to set a position of the proportional valve appropriate to the temperature conditions and the power requirement.

[0019] Fig.Figure 2 shows a highly schematic representation of the construction of the proportional valve 8. A housing 14 has a cylindrical interior, an inlet 15, and two outlets 16, 17. The interior contains a rotor 19, which is driven about an axis 18 by an actuator (not shown) under the control of the control unit 13. The rotor 19 is shaped such that, under normal operating conditions, it does not block the inlet 15 and changes the free cross-sections of the two outlets in an equally opposite manner, symbolized here by a circular segment-shaped element 20, which, to the extent that it moves in front of one of the outlets 16, 17 during a rotation about the axis 18, opens the other.

[0020] A laser scanner 21 is arranged in a plane offset along axis 18 relative to the inputs and outputs 15, 16, 17, with a scanning direction parallel to axis 18. A detection area 22 of the laser scanner 21 can be defined by a slot in the housing 14 parallel to axis 18, through which the beam of the laser scanner 21 strikes a surface of the rotor 19.

[0021] On the surface of the 19 rotor, a multitude of elongated stripes 23 extending in the direction of the axis 18 are defined, each bearing a code readable by the laser scanner 21. Which of these stripes 23 lies within the detection area 22 depends on the rotation angle of the rotor 19 about the axis 18; by reading the code located within the detection area 22, the scanner 21 provides the control unit 13 with information about the rotation angle of the rotor 19.

[0022] It is not necessary for each strip 23 to contain all the information required to uniquely identify the angle of rotation. If at least one reference position of the rotor is uniquely identified, i.e., if the control unit 13 can unambiguously recognize that the rotor 19 is in the reference position based on the information read by the scanner 21 in the detection area 22, then it is sufficient if subsequent data visible in the detection area 22 enables the control unit to calculate the instantaneous angular displacement of the rotor 19 relative to the reference position. Reference sign 1 fuel cell 2 intercoolers 3 Outlets 4 outlets 5 Line section 6th branch 7 Passenger compartment heating 8 Proportional valve 9 Bypass 10 pump 11 Branch line 12 heat exchangers 13 Control unit 14 cases 15 Entrance 16 Exit 17 Exit 18 axle 19 Rotor 20 Element 21 laser scanners 22 Detection area 23 strips QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 1 688 605 B1

[0003]

Claims

[1] Proportional valve (8) with a housing (14) having a plurality of connections (15, 16, 17) and a rotor (19) which is rotatably mounted in the housing (14) about an axis (18) in order to vary a passage cross-section between at least two of the connections (15, 16, 17), characterized by that it comprises an optical data reading device and that code values ​​representative of an angle of rotation of the rotor (19) are applied to a circumferential region of the rotor (19) which is rotatable by a detection region (22) of the data reading device. [2] Proportional valve according to claim 1, wherein the detection area (22) is elongated in the direction of the axis (18). [3] Proportional valve according to claim 1 or 2, wherein the data reading device is a laser scanner (21). [4] Proportional valve according to one of the preceding claims, further comprising a motor and a control unit (13) for controlling the motor based on an output of the data reading device (21). [5] Cooling circuit in which the proportional valve (8) according to one of the preceding claims is arranged to divide a coolant flow between a heat exchanger (12) and a bypass (9) parallel to the heat exchanger. [6] Cooling circuit according to claim 5, which has a fuel cell (1) and / or a charge air cooler (2) as heat source and / or in which the heat exchanger (12) is a cooler flushed with ambient air. [7] Cooling circuit according to claim 6, which further supplies a passenger compartment heater (7). [8] Motor vehicle with a proportional valve according to one of claims 1 to 4 or a cooling circuit according to one of claims 5 to 7.

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