ACTUATION SYSTEM TO ACHIEVE SOFT LANDING AND THE CONTROL METHOD THEREOF

Abstract

An actuation system to achieve soft landing and the control method thereof are provided. A soft landing is achieved via an open loop control of an electromagnetic actuator. The actuation system includes a control unit, wherein the control unit controls the electromagnetic actuator. The control unit does not rely on sensor data regarding a position of an armature to achieve the soft landing. As the actuation system achieves soft landing via the open loop control of the electromagnetic actuator by the control unit, a use of the sensor data is not needed.

Claims

1. An actuation system, comprising an electromagnetic actuator, wherein the electromagnetic actuator comprises a body, at least one coil, and an armature to convert an electrical energy into a mechanical energy, a control unit, wherein the control unit applies a voltage signal to the electromagnetic actuator on the at least one coil for an open loop control of the electromagnetic actuator to achieve a soft landing, wherein a first portion of the voltage signal is applied to energize the at least one coil, a second portion of the voltage signal is applied after the voltage signal is closed and an admittance time is finished to generate the soft landing of the armature (3) and, the second portion of the voltage is applied for a period of time shorter than a period of application of the first portion of the voltage signal.

2. The actuation system according to claim 1, wherein magnitudes of the first portion of the voltage signal and the second portion of the voltage signal are equal to each other.

3. The actuation system according to claim 1, wherein a waiting time between the first portion and the second portion of the voltage signal is T.sub.wait and T.sub.wait is calculated by adding the period of time required to reach an admittance of the electromagnetic actuator after the first portion of the voltage signal is finished and a period of time required for a closing of the armature multiplied with a first constant value, wherein the first constant value is determined by a manufacturer according to first parameters of the electromagnetic actuator.

4. The actuation system according to claim 3, wherein the second portion of the voltage signal is applied for a period of time T.sub.width and T.sub.width is calculated by a multiplication of a second constant value, wherein the second constant value is determined by a producer according to second parameters of the electromagnetic actuator with a time for the electromagnetic actuator to reach a maximum of the electromagnetic actuator or a movement of the armature.

5. The actuation system according to claim 4, wherein the first constant value is 0.33 and the second constant value is 0.5.

6. A method for controlling the actuation system according to claim 1, comprising the following steps: applying the first portion of the voltage signal for an energization of the at least one coil by the control unit, after an end of the application of the first portion of the voltage signal waiting for a completion of the admittance time, after the admittance time is completed, while the armature is closing applying the second portion of the voltage signal.

7. The actuation system according to claim 2, wherein a waiting time between the first portion and the second portion of the voltage signal is T.sub.wait and T.sub.wait is calculated by adding the period of time required to reach an admittance of the electromagnetic actuator after the first portion of the voltage signal is finished and a period of time required for a closing of the armature multiplied with a first constant value, wherein the first constant value is determined by a manufacturer according to first parameters of the electromagnetic actuator.

8. The method according to claim 6, wherein magnitudes of the first portion of the voltage signal and the second portion of the voltage signal are equal to each other.

9. The method according to claim 6, wherein a waiting time between the first portion and the second portion of the voltage signal is T.sub.wait and T.sub.wait is calculated by adding the period of time required to reach an admittance of the electromagnetic actuator after the first portion of the voltage signal is finished and a period of time required for a closing of the armature multiplied with a first constant value, wherein the first constant value is determined by a manufacturer according to first parameters of the electromagnetic actuator.

10. The method according to claim 9, wherein the second portion of the voltage signal is applied for a period of time T.sub.width and T.sub.width is calculated by a multiplication of a second constant value, wherein the second constant value is determined by a producer according to second parameters of the electromagnetic actuator with a time for the electromagnetic actuator to reach a maximum of the electromagnetic actuator or a movement of the armature.

11. The method according to claim 10, wherein the first constant value is 0.33 and the second constant value is 0.5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The electromagnetic actuator realized in order to attain the aim of the present invention is illustrated in the attached figures, where:

[0022] FIG. 1—is the schematic view of an electromagnetic actuator.

[0023] FIG. 2—is the voltage profile for control of an electromagnetic actuator.

[0024] The elements illustrated in the figures and the steps are numbered as follows: [0025] 1. Actuation system [0026] 2. Electromagnetic actuator [0027] 3. Armature (Plunger) [0028] 4. Coil [0029] 5. Control unit

[0030] The following symbols are used so that the present invention is understood better: [0031] T1. The time required to build magnetic force to pull the armature via the first portion of the voltage signal. [0032] T2. The time for the movement of the armature via the first portion of the voltage signal. [0033] T3. The opened position of the armature caused by the voltage signal. [0034] T4. The closing time of the first portion of the voltage signal. [0035] T5. The admittance time. [0036] T6. The movement of the closing of the armature. [0037] T7. The second portion of the voltage signal duration.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The actuation system (1) comprising [0039] an electromagnetic actuator (2) which comprises a body, at least one coil (4), an armature (3) to convert electrical energy into mechanical energy and [0040] a control unit (5) that applies the voltage signal to the electromagnetic actuator (2) on the coil (4) for the open loop control of the electromagnetic actuator (2) to achieve soft landing and wherein [0041] a first portion of the said voltage signal is applied to energize the coil (4) and [0042] a second portion of the voltage signal is applied after the first voltage signal is closed and the admittance time is finished to generate a soft-landing of the armature (3) and,
wherein [0043] the second portion of the voltage is applied for a period of time shorter than the period of application of the first portion of the voltage signal (FIG. 1).

[0044] The control unit (5) of the present invention applies the voltage in two portions. The first portion of the voltage signal energizes the electromagnetic actuator (2), which causes the movement of the armature (3) while necessary holding force is achieved. After the first portion of the voltage signal ends, the residual magnetism begins to die, and the holding force weakens accordingly. As a result, the armature (3) starts moving in the opposite direction. Meanwhile the control unit (5) applies the second portion of the voltage signal which helps in the soft-landing process of the armature (3) of the electromagnetic actuator (2). The second portion of the voltage signal is a surge applied at a specific point and for a specific time, which is determined by the certain electromagnetic actuator's (2) parameters.

[0045] In a particular embodiment of the present invention the voltage signal is a pulse width modulation (PWM) signal.

[0046] In an embodiment of the present invention, the magnitudes of the first and second portion of the voltage signals are equal to each other.

[0047] In another embodiment of the present invention, the waiting time between the first portion and the second portion of the voltage signal (T.sub.wait) has been calculated by adding the period of time required to reach the admittance of the electromagnetic actuator (2) after the first portion of the voltage signal is finished (T.sub.5) and the period of time required for the closing of armature (3)(T.sub.6) multiplied with a constant value which is determined by the manufacturer according to the certain electromagnetic actuator's (2) parameters (A).

T.sub.wait=T.sub.5+A*T.sub.6

[0048] Then the second portion of the voltage signal is applied for a period of time (T.sub.width) that has been calculated by the multiplication of a constant value which is determined by the producer according to the certain electromagnetic actuator's (2) parameters (B) with the time for electromagnetic actuator (2) to reach its maximum or the movement of the armature (3) (T.sub.2).

T.sub.width=B*T.sub.2

[0049] For different embodiments of the invention values of A and B shall be determined according to the actuator (2) type that is being used. Once the preferred value for A and B is determined the working range to be determined for the A and B values by taking a plus minus 5-10% margin into account. All these values depend on the physical parameters and electromagnetic properties of the electromagnetic actuators (2). These parameters are different for different electromagnetic actuators (2). Physical parameters and electromagnetic properties that affect the T.sub.wait and T.sub.width are: Materials used, mass of armature (3), no. of turns of the coil (4), springs constant, coil (4) resistance. If the physical parameters of the solenoid are known, then one can create an electromechanical model of the solenoid to simulate the motion of the armature (3), in accordance with the given voltage input. By checking the simulation results one can infer, what these constants ‘A’ and ‘B’ are.

[0050] In the preferred embodiment of the present invention, the “A” value for the particular actuator (2) used has been observed to be 0.33 and “B” value has been observed to be 0.5 to achieve soft-landing. Similarly, the working range of the A and B values for this particular actuator (2) can be calculated by using a 5-10% margin from the observed A value and B values simultaneously. The range of ‘A’ and ‘B’ is in between 0.1 and 0.9.

[0051] In the preferred embodiment of the present invention, electromagnetic actuator (2) is operated 24 V DC (FIG. 2).

[0052] The control method of the present invention used in the above-disclosed actuation system (1) and executed by the control unit (5), comprises the following steps for providing a soft-landing of the armature (3), [0053] applying the first portion of the voltage signal for the energization of the coil (4) by control unit (5), [0054] after the end of the application of the first portion of the voltage waiting for the completion of an admittance time, [0055] after the admittance time is completed, while the armature (3) is closing applying the second portion of the voltage signal.

[0056] According to the present invention cost effective and easy open loop control method for the movement of the armature (3) is provided. As the system, contrary to the closed loop systems known in the art, does not rely on the position feedback from the encoders, the resulting soft landing is comparatively easy to achieve when the output is difficult to measure and is more stable. Further as there is no need to use sensors to obtain the position data, it is more cost-effective. Additionally, the lifespan of electromagnetic actuator (2) is increased, and undesirable operational noise is much reduced.