Method for controlling an electromagnetic drive unit

Abstract

Method for controlling an electromagnetic drive unit (10), in particular for a valve assembly, wherein the drive unit (10) comprises a stator for generating a magnetic field and a rotor (31) for converting the magnetic field into a driving motion, wherein the drive unit (10) is designed to be connectable to a valve unit comprising a closing element (22) and a valve seat (26), and the closing element (22) can be moved by the drive unit (10) between a closed position in which the closing element (22) rests against a valve seat (26) and an open position in which the closing element (22) is spaced away from the valve seat (26), the procedure comprises the following steps: - Transferring (100) the closing element (22) from a first position to a second position at a predetermined control speed by actuating the drive unit (10), and - Pulse-like actuation (200) of the drive unit (10) when the actual speed of the closing element (22) is below the control speed.

Description

[0001] The invention relates to a method for controlling an electromagnetic drive unit, in particular for a valve assembly. The drive unit comprises a stator for generating a magnetic field and a rotor for converting the magnetic field into a drive movement, wherein the drive unit is designed to be connectable to a valve unit comprising a closing element and a valve seat. The closing element can be moved by the drive unit between a closed position, in which the closing element rests against a valve seat, and an open position, in which the closing element is spaced away from the valve seat. The method comprises the steps of moving the closing element into the closed position by actuating the drive unit, and pulse-like actuating of the drive unit to increase the contact force between the closing element and the valve seat.

[0002] These types of valve assemblies are used particularly in vehicle refrigerant systems, which in many cases are part of a vehicle's air conditioning system. Specifically, such vehicle refrigerant systems are used in vehicle air conditioning units that regulate the temperature of a vehicle's interior. These systems often use chemical refrigerants such as 2,3,3,3-tetrafluoropropene (R1234YF). Carbon dioxide is also frequently used as an alternative refrigerant.

[0003] Valve assemblies for vehicle refrigerant systems are known from the prior art. These valve assemblies have a drive unit that generates a rotary drive motion. This rotary drive motion is transmitted via a threaded coupling to a closing element, which, due to the threaded coupling, performs a translational movement. The closing element can be moved from an open position to a closed position. In the closed position, the closing element seals off a refrigerant inlet. For this purpose, the closing element rests against a valve seat. A common problem is the occurrence of leaks when the closing element is in the closed position. In the prior art, this is addressed, for example, by increasing the contact force of the closing element against the valve seat. However, this requires powerful drives, which leads to correspondingly high costs.Alternatively, or in combination with increasing the contact force of the closing element against the valve seat, current technology attempts to reduce leakage through precise manufacturing and high surface quality. This measure also leads to increased costs.

[0004] DE 10 2010 045 504 A1 relates to a valve assembly and a method for controlling a ballistic movement of a valve's locking element. The locking element, which is designed to block a flow cross-section of the valve and can be moved between a first switching position and a second switching position, assumes the first switching position in its rest position and is moved from this position in response to an activation signal. The movement is controlled by dimensioning the duration of the activation signal such that, before reaching the second switching position, the locking element is moved back to the first switching position by a counterforce, thereby at least partially opening the flow cross-section during the movement.

[0005] DE 10 2016 207 564 B3 relates to a switching valve and a method for opening and closing the switching valve, in which the switching valve is provided with a winding, a spring, and a valve element that is movable between two end positions. A spring force transmitted to the valve element acts towards the first end position, and when the winding is energized, a force acting towards the second end position is transmitted to the valve element. The method further includes connecting a power supply device to the winding for generating pulse-width modulated voltage signals.

[0006] JP 2019 - 221 020 A relates to an engine control unit, an integrated valve and a heat exchanger, wherein the engine control unit controls a motor to actuate a valve body of the valve by means of pulse width modulation.

[0007] DE 100 33 909 A1 relates, for example, to a method and a device for controlling at least one valve, in which, when a leak is detected in the system encompassing the valve, a control signal is generated which briefly opens and closes the valve for flushing or moves the valve ball onto the valve seat at high speed.

[0008] The object of the invention is therefore to provide an improved method for controlling an electromagnetic drive unit that, on the one hand, ensures an increase in the contact force of the closing element against the valve seat and thus a reduction in leakage without requiring a more powerful and therefore more expensive drive unit. On the other hand, the method should be able to overcome or dissolve impurities that occur in the valve unit during operation. Furthermore, it is an object of the invention to provide a computer-readable medium for such a method.

[0009] According to the invention, this problem is solved with regard to the method for controlling an electromagnetic drive unit by the subject matter of claim 1 and with regard to the computer-readable medium by the subject matter of claim 10.

[0010] The normal process of controlling the valve unit involves moving the closing element from a first position to a second position at a predetermined speed by actuating the drive unit. However, the closing element can be impeded by contamination, blockages, or other obstructions. Consequently, the drive unit is no longer able to maintain the controlled speed. According to the invention, by pulse-like actuation of the drive unit when the actual speed of the closing element is below the controlled speed, these blockages or contaminations can be overcome.

[0011] The control speed can be predetermined due to the specific design of the drive as a stepper motor. Instead of the control speed, the step speed of the stepper motor could also be used as the basis. Alternatively or additionally, the load torque could be measured and used as the basis for the pulsed actuation of the drive.

[0012] Pulsed actuation could also be understood as oscillating actuation of the stepper motor. In this case, the stepper motor is energized in a correspondingly pulsed manner.

[0013] According to an advantageous embodiment, the closing element is moved at the controlled speed by means of a first torque, and this torque is increased to a second torque during pulsed actuation. This achieves, for example, the technical advantage that the maximum torque of the drive unit is reached before the pulsed actuation is applied.

[0014] In an advantageous embodiment, the drive unit is actuated in pulses by means of the second torque. This increases the efficiency of the process and allows blockages to be overcome more easily.

[0015] In a particularly preferred embodiment, the first torque is a maximum of 30 mNm. In a further particularly preferred embodiment, the first torque is a maximum of 50 mNm. In yet another particularly preferred embodiment, the first torque is a maximum of 100 mNm.

[0016] To complete the transfer of the locking element from a first position to a second position after overcoming a blockage, the pulsed actuation of the drive unit is stopped when the actual speed of the locking element reaches the control speed.

[0017] According to a particularly advantageous embodiment, the second position corresponds to the closed position and the pulse-like actuation of the drive unit is performed to increase the contact force between the closing element and the valve seat.

[0018] By actuating the actuator unit, the closing force of the valve body is already generated, determined by the torque of the actuator unit itself. Pulsating the actuator unit to increase the contact force between the valve body and the valve seat combines the maximum torque of the actuator unit with the inertia of the system to increase the closing force in the end position. This ultimately increases the contact force of the valve body against the valve seat and thus improves the seal. Consequently, leakage can be reduced.

[0019] To achieve the most effective pulsed actuation of the drive unit, pulsed actuation of the drive unit also occurs in the closed position over a time interval of a maximum of 1 / 10 of a second. Preferably, the pulsed actuation of the drive unit occurs over a time interval of a maximum of 1 second. Preferably, the pulsed actuation of the drive unit occurs over a time interval of a maximum of 5 seconds.

[0020] In a particularly preferred embodiment, the drive unit is actuated in pulses at a frequency of at least 10 Hz, even in the closed position. In a further advantageous embodiment, the drive unit is actuated in pulses at a frequency of at least 100 Hz. In yet another embodiment, the drive unit is actuated in pulses at a frequency of at least 150 Hz.

[0021] In order to open a drive unit located in the closed position and to space the closing element away from the valve seat, the method according to the invention comprises the following steps of moving the closing element from the closed position to the open position by pulse-like actuation of the drive unit, and stopping the pulse-like actuation of the drive unit as soon as the closing element continuously reaches the control speed.

[0022] The transition to the first step can also be understood as releasing the locking element from the closed position to the open position.

[0023] This achieves, for example, the technical advantage that opening the actuator unit results in the same benefit. High holding forces of the valve body with the valve seat can be overcome by pulsed actuation of the actuator unit. For example, contamination or similar factors can cause the opening of the valve assembly to be inhibited or blocked. In such a case, pulsed actuation is also used, allowing blockages or contamination to be overcome. As soon as the holding force or blockage of the valve body is overcome, the pulsed actuation of the actuator unit ends, and the actuator continues to run at the controlled speed. "Continuous" in this context means that the actual speed is not only achieved briefly, for example, in the form of oscillation or vibration effects.Continuous means that blockages or holding forces have been overcome and the control speed has returned to the predetermined normal state.

[0024] Even when the valve assembly opens, the pulsed actuation of the drive unit has a time interval of at least 1 / 10 of a second. Preferably, the pulsed actuation of the drive unit has a time interval of at least 1 second.

[0025] According to a further preferred embodiment, the drive unit is also actuated in pulses at a frequency of at least 50 Hz when opening. According to a further advantageous embodiment, the drive unit is actuated in pulses at a frequency of at least 100 Hz. According to yet another embodiment, the drive unit is actuated in pulses at a frequency of at least 150 Hz.

[0026] For example, the drive's power output ranges from 0.5 W to 10 W. However, in application-specific cases, the power output may also fall outside this range.

[0027] With regard to the computer-readable medium and with regard to the equipment with means for carrying out the steps of the method according to the invention, comparable advantages arise as those explained above.

[0028] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying schematic drawings. These show: Fig. 1 a longitudinal sectional view through a valve assembly according to the invention in a preferred embodiment; Fig. 2 a schematic sequence of an embodiment of the method according to the invention, Fig. 3 a schematic sequence of a further embodiment of the method according to the invention, and Fig. 4 a schematic sequence of a further embodiment of the method according to the invention.

[0029] Basically, identical parts in the figures are marked with the same reference symbols.

[0030] In the longitudinal section view according to Fig. Figure 1 shows a valve assembly comprising an actuator unit 10, a valve unit 20, and a closing element 22. The closing element 22 is guided within the valve unit 20. The closing element 22 engages in a valve flow chamber 18, in which a valve seat 26 is formed. The valve seat 26 is associated with a first fluid flow port 14 of the valve unit 20. Second fluid flow ports 15 are arranged laterally in the valve flow chamber 18, through which fluid can flow into or out of the valve flow chamber 18.

[0031] The closing element 22 can seal against the valve seat 26 to prevent fluid flow through the first fluid flow port 14. The closing element 22 can be moved or displaced along a closing element longitudinal axis L by means of the drive unit 10, so that the closing element 22 can allow or interrupt fluid flow between the first fluid flow port 14 and the second fluid flow ports 15.

[0032] The closing element 22 is essentially elongated and rotationally symmetrical. Inside the closing element 22 extends a hollow channel 36, which enables a fluid connection between the valve flow chamber 18 and a valve body chamber 13 formed in the drive unit 10.

[0033] The movement of the closing element 22 is effected by the drive unit 10, which has a rotor 31 and a stator, which is in Fig. Figure 1 is not shown. A containment shell 32 is located between the rotor 31 and the stator, extending through the gap between the rotor 31 and the stator. The containment shell 32 is sealed and firmly connected to the valve unit 20. The connection can be made, in particular, by welding.

[0034] The rotor 31 is coupled to a drive shaft 11 by means of a coupling 25, which can be designed, for example, as an Oldham coupling or a cross-slide coupling. The drive shaft 11 has an external thread at one end facing the valve seat, which engages in an internal thread of the closing element 22. The threaded coupling 12 causes the closing element 22 to be converted into a translational movement along the longitudinal axis L of the closing element by a rotational movement of the drive shaft 11.

[0035] The drive shaft 11 is supported in the valve unit 20 by a drive shaft bearing 24. The drive shaft bearing 24 can in particular be a rolling bearing, preferably a ball bearing.

[0036] The valve flow chamber 18 is arranged in a valve housing 23, which can be formed integrally with the valve unit 20. In the embodiment shown here, the valve housing 23 is provided as a separate component, which is connected to the valve unit 20. The connection can be permanent and, for example, made by welding.

[0037] The locking element 22 can be moved from an open position to a closed position. This is accomplished by the drive unit 10, which guides the locking element 22 into a translational movement via the drive shaft 11. Fig. Figure 1 shows the closing element 22 in the closed position. In the closed position, the closing element 22 rests flush against the valve seat 26. The valve unit 20 has a guide channel 21, the length of which determines the maximum translational movement of the closing element 22.

[0038] The hollow channel 36 in the closing body 22 allows fluid from the first fluid flow connection 14 to pass through the hollow channel 36 into the valve body chamber 13, which is formed in the containment cup 32. In this way, pressure equalization is achieved on both sides of the closing body 22. The hollow channel 36 can also extend over the drive shaft 11. Preferably, however, the pressure equalization fluid connection is made via the threaded coupling 12. The interlocking threads of the drive unit 11 and the closing body 22 preferably have sufficient clearance to allow fluid, in particular refrigerant, to flow through them.

[0039] In the closed position, it is advantageous to ensure that fluid exchange occurs exclusively via the hollow channel 36. Any bypasses, for example by flowing around the closing element 22 on its outside, should be avoided. Therefore, a rod seal 39 is provided in the valve assembly, located between the valve unit 20 and the closing element 22.

[0040] In the embodiment according to Fig. Specifically, it is provided that the valve unit 20, in particular the valve housing 23, has a receptacle 29 for the rod seal 39. The rod seal 39 is preferably designed as a PTFE-free O-ring, for example made of a rubber material. The rod seal 39 is fixed in the receptacle 29, in particular by a form-fit in the longitudinal axial direction.

[0041] In the Fig. In the closed position shown in Figure 1, the rod seal 39 seals between the valve unit 20 and the closing element 22. After leaving the closed position, i.e., when transitioning to the open position of the closing element 22, the sealing effect may diminish, since bypass flows of the refrigerant are harmless in other positions outside the closed position of the closing element 22. Therefore, it is advantageous that the invention provides for reducing the friction generated between the valve unit 20 and the closing element 22 by the tension of the rod seal 39 in positions outside the closed position. This prevents wear and reduces the force required by the drive unit 10 to move the closing element 22.

[0042] In the open position, the closing element 22 is removed from the valve seat 26, allowing fluid to flow into the valve flow chamber 18 via the first fluid flow port 14 and out of the valve flow chamber 18 via the second fluid flow ports 15. The fluid, preferably refrigerant, can therefore flow from the first fluid flow port 14 to the second fluid flow port 15.

[0043] In the embodiment shown here, the closing element 22 has a sealing geometry that interacts with the rod seal 39 such that the rod seal 39 is arranged to seal in the closed position of the closing element 22 and is slidably mounted between the closing element 22 and the valve unit in the open position. In the embodiments shown here, this sealing geometry is achieved by two diameter sections that differ in their cross-sectional diameter. Specifically, the closing element 22 has a first diameter section 28A, which has a larger cross-sectional diameter than a second diameter section 28B. The second diameter section 28B is located on the valve seat side. The first diameter section 28A is located on the actuator side of the closing element 22.

[0044] A transition section is arranged between the first diameter section 28A and the second diameter section 28B. The transition section essentially forms a conical or frustoconical taper, which causes a smooth transition between the first diameter section 28A and the second diameter section 28B.

[0045] The Fig. Figure 2 shows a schematic sequence of an embodiment of the method according to the invention. In the first step, the closing element 22 is moved 100 from a first position to a second position at a controlled speed by actuating the drive unit 10. For example, the closing element 22 is located in a position spaced apart from the valve seat 26 and is to be moved closer to the valve seat 26. During the control path between the first and second positions, the closing element 22 may become blocked, for example, due to contamination. In the second step of the method, the drive unit 10 is actuated 200 in a pulsed manner when the actual speed of the closing element 22 falls below the controlled speed. Due to the contamination or the blockage, the closing element 22 is impeded, which means that the drive unit 10 is no longer able to maintain the controlled speed. Consequently, it drops.By pulse-like actuation 200 of the drive unit 10 according to the invention when the actual speed of the closing element 22 falls below the control speed, the blockages or impurities can be overcome.

[0046] According to another example, the second position can correspond to the closed position and the pulsed actuation 200 of the drive unit 10 is performed to increase the contact force between the closing element 22 and the valve seat 26.

[0047] By moving the closing element 22 into the closed position by actuating the drive unit 10, a contact force is already generated, which is determined by the torque of the drive unit 10 itself. By pulsating 200 of the drive unit 10 to increase the contact force between the closing element 22 and the valve seat 26, the maximum torque of the drive unit 10 is combined with the inertia of the system to increase the closing force in the end position. This ultimately increases the contact force of the closing element 22 on the valve seat 26 and thus the sealing. Consequently, leakage can be reduced.

[0048] The Fig. Figure 3 shows a schematic sequence of a further embodiment of the method according to the invention. In contrast to the Fig. Following the process steps of moving the locking element 22 from a first position to a second position at a controlled speed by actuating the drive unit 10, and the pulsed actuation 200 of the drive unit 10 when the actual speed of the locking element 22 falls below the controlled speed, a further process step is carried out. In this third step, the pulsed actuation 200 of the drive unit 10 is discontinued when the actual speed of the locking element 22 reaches the controlled speed.

[0049] This embodiment enables the completion of the movement of the closing element 22 from the first position to the second position, whereby any obstruction encountered on the path between the first and second positions has been overcome. In other words, the method according to the invention ensures that a return to the controlled speed is possible.

[0050] The Fig. Figure 4 shows a schematic sequence of a further embodiment of the method according to the invention. Here, the closing element 22 is in contact with the valve seat 26. High clamping forces or adhesion of the closing element 22 to the valve seat 26 can occur, so in the first step, the closing element 22 is moved 300 from the closed position to an open position by pulsed actuation of the drive unit 10. High holding forces of the closing element with the valve seat can be overcome by pulsed actuation of the drive unit. In the second step, the pulsed actuation 400 of the drive unit 10 is discontinued as soon as the closing element 22 has reached the control speed. As soon as the holding force or the blockage of the closing element is overcome, the pulsed actuation of the drive unit ends and the drive continues to run at the control speed. Reference symbol list 10 Drive unit 11 Drive shaft 12 threaded couplings 13 Valve body chamber 14 First fluid flow connection 15 Second fluid flow connection 18 Valve flow chamber 20 valve unit 21 Guide channel 22 locking elements 23 Valve housings 24 drive shaft bearings 25 Clutch 26 Valve seat 27 Contact area 28A First diameter section 28B Second diameter section 29th entry 31 Rotor 32 Split pot 36 Hollow channel 39 rod seal L Longitudinal axis of the closing element LK line contact I Inclination 100 Moving the locking mechanism into the closed position 200 pulse-like activation of the drive unit 300 Moving the locking mechanism from the closed position to the open position 400 Setting the pulse-like actuation of the drive unit

Claims

[1] Method for controlling an electromagnetic drive unit (10), in particular for a valve assembly, wherein the drive unit (10) comprises a stator for generating a magnetic field and a rotor (31) for converting the magnetic field into a driving motion, wherein the drive unit (10) is designed to be connectable to a valve unit comprising a closing element (22) and a valve seat (26), and the closing element (22) can be moved by the drive unit (10) between a closed position in which the closing element (22) rests against a valve seat (26) and an open position in which the closing element (22) is spaced away from the valve seat (26), the procedure comprises the following steps: - Transferring (100) the closing element (22) from a first position to a second position at a predetermined control speed by actuating the drive unit (10), and - Pulse-like actuation (200) of the drive unit (10) when the actual speed of the closing element (22) is below the control speed. [2] Method according to claim 1, wherein the transfer of the closing element (22) is carried out at the control speed by means of a first torque and the torque is increased to a second torque during pulse-like actuation (200). [3] Method according to claim 2, wherein the pulse-like actuation (200) of the drive unit (10) is carried out by means of the second torque. [4] Method according to claim 2 or 3, wherein the first torque is a maximum of 30 mNm, in particular a maximum of 50 mNm, in particular a maximum of 100 mNm. [5] Method according to one of the preceding claims, wherein the pulse-like actuation (200) of the drive unit (10) takes place over a time interval of a maximum of 1 / 10 second, in particular over a time interval of a maximum of 1 second, in particular over a time interval of a maximum of 5 seconds. [6] Method according to one of the preceding claims, wherein the pulse-like actuation (200) of the drive unit (10) is carried out at a frequency of at least 10 Hz, in particular at a frequency of at least 100 Hz, in particular at a frequency of at least 150 Hz. [7] Method according to one of the preceding claims, wherein the pulse-like actuation (200) of the drive unit (10) is stopped (400) when the actual speed of the closing element (22) continuously reaches the control speed. [8] Method according to one of the preceding claims, wherein the second position corresponds to the closed position and the pulse-like actuation (200) of the drive unit (10) is performed to increase the contact force between the closing element (22) and the valve seat (26). [9] A method according to any of the preceding claims, wherein the method comprises the following steps: - Moving (300) the locking element (22) from the closed position to the open position by pulse-like actuation of the drive unit (10), and - Setting (400) the pulse-like actuation of the drive unit (10) as soon as the closing element (22) continuously reaches the control speed. [10] Computer-readable medium with program code adapted to perform all the process steps according to any one of claims 1 to 9 when the program code is executed on a computer. [11] Equipment comprising means for carrying out the steps of the method according to any one of claims 1 to 9. [12] Device according to claim 11, wherein the device is designed as an embedded system or embedded circuit.

Images