Device and method for detecting filter clogging

Abstract

The present disclosure relates to a device and to a method for detecting filter soiling of a filter system having at least an air filter installed in an air duct and an electrically controlled fan for producing an air flow in the air duct, wherein the device comprises at least a motor controller for controlling the fan motor by means of PWM control and an evaluating apparatus for determining the actual rotational speed (n.sub.i) of the fan in accordance with the actual degree of modulation (T.sub.i) of the motor current for achieving the present rotational speed (n.sub.i), wherein, in the evaluating apparatus, setpoint value pairs (n.sub.setpoint, T.sub.setpoint) for the setpoint rotational speed (n.sub.setpoint) at a certain degree of modulation (T.sub.setpoint) are also stored, as well as a comparator in order to compare the actual value pairs (n.sub.i, T.sub.i) with the setpoint value pairs (n.sub.setpoint, T.sub.setpoint) and to obtain the degree of filter soiling of the air filter therefrom.

Claims

1. A device for detecting filter soiling of a filter system having at least an air filter installed in an air duct and an electrically controlled fan having a fan motor for producing an air flow in the air duct, wherein the device comprises: at least a motor controller for controlling the fan motor by means of pulse width modulation (PWM) control, and an evaluating apparatus for determining an actual rotational speed (n.sub.i) of the fan in accordance with an actual degree of modulation (T.sub.i) of a motor current for achieving the actual rotational speed (n.sub.i), wherein, in the evaluating apparatus, setpoint value pairs (n.sub.setpoint, T.sub.setpoint) for a setpoint rotational speed (n.sub.setpoint) at a setpoint degree of modulation (T.sub.setpoint) are also stored, the evaluating apparatus including a comparator which is configured to compare the actual value pairs (n.sub.i, T.sub.i) with the setpoint value pairs (n.sub.setpoint, T.sub.setpoint) and to obtain a degree of filter soiling of the air filter therefrom as well as from an intermediate circuit voltage and an intermediate circuit current.

2. A detection method with the device according to claim 1, wherein the degree of filter soiling is obtained from a power consumption of the fan motor without using sensors in that an actual power consumption, which can be determined by the actual value pairs (n.sub.i, T.sub.i), is compared to a defined setpoint power consumption of an unsoiled filter system in the comparison, which can be determined by the setpoint value pairs (n.sub.setpoint, T.sub.setpoint), wherein the intermediate circuit voltage and the intermediate circuit current are recorded and used in the evaluation of the degree of filter soiling.

3. The detection method according to claim 2, having the following steps: a. determining the actual rotational speed (n.sub.i) of the fan, b. determining the actual degree of modulation (T.sub.i) of the motor current in order to achieve the actual rotational speed (n.sub.i), c. comparing the actual value pairs (n.sub.i, T.sub.i) with stored setpoint value pairs (n.sub.setpoint, T.sub.setpoint), and d. determining whether a deviation of the actual value pairs (n.sub.i, T.sub.i) from the setpoint value pairs (n.sub.setpoint, T.sub.setpoint) is within or outside the maximum predefined deviation.

4. The detection method according to claim 3, wherein the evaluation of the degree of filter soiling takes place from the power consumption of the fan and by means of a stored fan characteristic curve.

5. The detection method according to claim 2, wherein a reporting of a soiled air filter is output as a signal when the maximum deviation of the actual values from the setpoint values is exceeded.

6. The detection method according to claim 2, wherein the direction of rotation of the fan is reversed for a defined time as compared to a forward rotational direction and, in doing so, the actual degree of modulation, the actual rotational speed, and the intermediate circuit current and the intermediate circuit voltage are continuously recorded.

7. The detection method according to claim 2, wherein a jump in rotational speed is initiated by way of a motor controller with the fan, and a response in a PWM signal to the jump is recorded and evaluated.

8. A detection method for determining filter soiling of a filter system having at least an air filter installed in an air duct and an electrically controlled fan for producing an air flow in the air duct, wherein a motor controller and an evaluating apparatus are provided, having the following steps: a. determining an actual rotational speed (n.sub.i) of the fan, b. determining an actual degree of modulation (T.sub.i) of the motor current in order to achieve the actual rotational speed (n.sub.i), c. comparing the actual value pairs (n.sub.i, T.sub.i) with stored setpoint value pairs (n.sub.setpoint, T.sub.setpoint), d. determining whether a deviation of the actual value pairs (n.sub.i, T.sub.i) from the setpoint value pairs n.sub.setpoint, T.sub.setpoint) exceeds a maximum predefined deviation, e. recording an intermediate circuit voltage and an intermediate circuit current, and f. evaluating the deviation of the actual value pairs (n.sub.i, T.sub.i) from the setpoint value pairs (n.sub.setpoint, T.sub.setpoint) as well as evaluating the intermediate circuit voltage and the intermediate circuit current to obtain a degree of filter soiling.

9. The detection method according to claim 8, wherein a reporting of a soiled air filter is output as a signal when the maximum deviation of the actual values from the setpoint values is exceeded.

10. The detection method according to claim 8, wherein the direction of rotation of the fan is reversed for a defined time as compared to a forward rotational direction and, in doing so, the actual degree of modulation, the actual rotational speed, and the intermediate circuit current and the intermediate circuit voltage are continuously recorded.

11. The detection method according to claim 8, wherein a jump in rotational speed is initiated by way of a motor controller with the fan, and a response in a PWM signal to the jump is recorded and evaluated.

12. The detection method according to claim 8, wherein the degree of filter soiling is obtained from a power consumption of the fan motor without using sensors in that an actual power consumption, which can be determined by the actual value pairs (n.sub.i, T.sub.i), is compared to a defined setpoint power consumption of an unsoiled filter system in the comparison, which can be determined by the setpoint value pairs (n.sub.setpoint, T.sub.setpoint).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following is shown in the drawings:

(2) FIG. 1 a schematic view of a device according to the present disclosure; and

(3) FIG. 2 a schematic representation of the steps of the method according to the present disclosure.

DETAILED DESCRIPTION

(4) The present disclosure is described in the following using an exemplary embodiment, wherein use of the same reference characters indicates the same structural and/or functional features.

(5) FIG. 1 shows a schematic view of an exemplary embodiment of a device 1 for detecting filter soiling in the filter system 2, wherein the filter system 2 consists of at least an air filter 10 installed in an air duct 20 and an electrically controlled fan 30 creating an air flow in the air duct 20. The device 1 has a motor controller 40 for controlling the fan motor, wherein a PWM control 32 is provided for regulating rotational speed. Furthermore, an evaluating apparatus 50 for determining the actual rotational speed n.sub.i of the fan 30 as a function of the actual degree of modulation (duty cycle) of the engine current is provided for achieving the current rotation speed n.sub.i.

(6) Furthermore, setpoint value pairs n.sub.setpoint, T.sub.setpoint for the setpoint rotational speed n.sub.setpoint of the filter system 2 at a certain degree of modulation T.sub.setpoint are stored in the evaluating apparatus 50. Moreover, a comparator 51 is provided in the device in order to compare the respective actual value pairs n.sub.i, T.sub.i with the stored setpoint value pairs n.sub.setpoint, T.sub.setpoint and from that determine the degree of filter soiling of the air fan 10. As soon as the deviation is greater than a specified limit value in a tolerance range, a signal is output to the LED light 61 via the interface 60, which indicates impermissible filter soiling.

(7) FIG. 2 shows a schematic representation of the steps of the detection method according to the disclosure for determining filter soiling of a filter system, which can be implemented with the device according to FIG. 1. The following steps are provided with the method.

(8) First, the recording or transmission of the motor characteristic curve related to the rotational speed as a function of the degree of modulation in the filter system 2, in which the air filter 10 is not soiled, thus, e.g., during system startup or a filter replacement, takes place in one step 100.

(9) These value pairs are stored as setpoint value pairs n.sub.setpoint, T.sub.setpoint in a data memory of the device 1 in step 110.

(10) During system operation, the respective determination of the actual rotational speed n.sub.i of the fan 30 and of the actual degree of modulation T.sub.i of the motor current takes place to achieve the current actual rotational speed n.sub.i in a step 120.

(11) In a further step 130, there is a comparison of the actual value pairs n.sub.i, T.sub.i with the stored setpoint value pairs n.sub.setpoint, T.sub.setpoint with the comparator 51 of the device 1.

(12) Subsequently, in step 140, the determination takes place as to whether the determined deviation of the actual value pairs n.sub.i, T.sub.i from the setpoint value pairs n.sub.setpoint, T.sub.setpoint exceeds a maximum predefined deviation. The deviation in this case can be determined as a range deviation in a permissible tolerance range, wherein either the rotational speed at a certain power consumption and thus a certain duty cycle is too low or whether an excessively high duty cycle is required in order to achieve a certain rotational speed. In particular, when the deviation of the actual values from the setpoint values has a linear characteristic over time, not only the current filter clogging but also the time of the maximally permissive soiling, at which a filter change should take place, can be predicted from the increasing deviation.