SPRING RETURN THROTTLE ACTUATOR, METHOD OF CONTROL THEREOF AND THROTTLE ASSEMBLY

Abstract

A spring return throttle actuator including: an electric, plural-coil DC motor having an output shaft, a throttle return spring, a gear transmission connected to the output shaft, a control unit adapted to control power supply to the DC motor, wherein the spring return throttle actuator has a movement range between closed throttle and fully opened throttle. The control unit includes a monitoring circuit adapted to monitor DC motor movement. The monitoring circuit is configured to receive signals from at least one voltage sensor adapted to sense voltage induced in at least one of the DC motor coils during a spring forced return of the throttle, and the monitoring circuit is configured to create a representation of DC motor movement based on said signals.

Claims

1. A spring return throttle actuator having a movement range between a closed throttle and a fully opened throttle, said actuator comprising: an electric, plural-coil DC motor having an output shaft; a throttle return spring; a gear transmission connected to the output shaft; a control unit adapted to control power supply to the DC motor; and a monitoring circuit adapted to monitor DC motor movement, wherein said monitoring circuit is configured to: receive signals from at least one voltage sensor adapted to sense voltage induced in at least one of the DC motor coils during a spring forced return of the throttle; and create a representation of DC.

2. An actuator according to claim 1, wherein the the at least one voltage sensor is configured to measure momentarily the voltage induced in at least one of the DC motor coils; and the monitoring circuit is configured to produce a momentary representation of the amplitude of the voltage measured by said voltage sensor to diagnose the spring.

3. An actuator according to claim 1, wherein the control unit comprises a bridge circuit comprising a plurality of branches, with one branch connected to each one of the coils.

4. An actuator according to claim 3, wherein each branch of said branch circuit comprises a transistor switch connected to each one of the coils.

5. An actuator according to claim 1, wherein the monitoring circuit is configured to compare measured rotational speed values of the DC motor to stored rotational speed profiles.

6. An actuator according to claim 1, wherein the monitoring circuit is configured to compare measured angular throttle position values to stored throttle position profiles.

7. A method of controlling a spring return throttle actuator having a movement range between a closed throttle and a fully opened throttle, wherein the actuator comprises an electric, plural-coil DC motor having an output shaft, a throttle return spring, a gear transmission connected to the output shaft, a control unit adapted to control power supply to the DC motor and a monitoring circuit comprising a voltage sensor, said method comprising: monitoring movement of the DC motor using the monitoring circuit; sensing a voltage induced in at least one of the DC motor coils during a spring forced return of the throttle using the voltage sensor of the monitoring circuit; and creating a representation of the DC motor movement.

8. A method according to claim 7, wherein the DC motor comprises three coils, and wherein the voltage induced in at least one of the DC motor coils is sensed.

9. A method according to claim 7, further comprising supplying the DC motor coils with power from each branch of a bridge circuit comprised in the control unit.

10. A method according to claim 7 further comprising measuring rotational speed values of the DC motor and comparing the measured rotational speed values to stored rotational speed profiles.

11. A method according to claim 7 further comprising measuring angular throttle position values and comparing the measured angular throttle position values to stored throttle position profiles.

12. A throttle assembly comprising a throttle and a spring return throttle actuator, having a movement range between a closed throttle and a fully opened throttle, said actuator comprising: an electric, plural-coil DC motor having an output shaft; a throttle return spring; a gear transmission connected to the output shaft; a control unit adapted to control power supply to the DC motor; and a monitoring circuit adapted to monitor DC motor movement, wherein said monitoring circuit is configured to: receive signals from at least one voltage sensor adapted to sense voltage induced in at least one of the DC motor coils during a spring forced return of the throttle; and create a representation of DC motor movement based on said signals.

13. A throttle assembly according to claim 12, wherein: the voltage sensor is configured to measure momentarily the voltage induced in at least one of the DC motor coils; and the monitoring circuit is configured to produce a momentary representation of the amplitude of the voltage measured by said voltage sensor to diagnose the spring.

14. A throttle assembly according to claim 12, wherein the control unit comprises a bridge circuit comprising a plurality of branches, with one branch connected to each one of the coils.

15. A throttle assembly according to claim 14, wherein each branch of said branch circuit comprises a transistor switch connected to each one of the coils.

16. A throttle assembly according to claim 12, wherein the monitoring circuit is configured to compare measured rotational speed values of the DC motor to stored rotational speed profiles.

17. A throttle assembly according to claim 12, wherein the monitoring circuit is configured to compare measured angular throttle position values to stored throttle position profiles.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0031] The invention will now be described in greater detail by way of embodiments and with reference to the annexed drawings, wherein:

[0032] FIG. 1 illustrates a throttle assembly including a spring return throttle actuator according to the invention,

[0033] FIG. 2 shows a control circuit for the inventive throttle actuator,

[0034] FIG. 3 shows a simplified flow chart over an inventive method,

[0035] FIG. 4 shows a diagram over measured voltage as a function of elapsed time, and

[0036] FIG. 5 shows a diagram over signal processed momentary rotational speed as a function of elapsed time.

DETAILED DESCRIPTION OF THE INVENTION

[0037] FIG. 1, shows a throttle assembly whereof a spring return throttle actuator is generally depicted with reference number 1. The actuator 1 includes a DC motor 2 having three coils C1, C2 and C3 in its stator S. The rotor R is as usual provided with a permanent rotor magnet 3 and an output shaft 4.

[0038] A gear transmission 5 is connected to the output shaft 4 and an outgoing shaft 6 from the gear transmission 5 is coupled with its distal end to a throttle shaft 7 of a throttle 8. The actuator has a movement range between closed throttle and fully opened throttle.

[0039] The throttle 8 is arranged in a channel 9 to control a gas stream flowing through the channel 9.

[0040] A throttle return spring 10 is positioned around the outgoing shaft 6 and functions to provide a spring torque urging the outgoing shaft 6 to rotate towards a normal position of the throttle 8 which may be fully open or fully closed depending on the nature of the throttle as explained above.

[0041] A control unit CPU is connected to the DC motor and is adapted to control supply of power to the DC motor and thereby to control the throttle position. Movement sensors, preferably Hall effect sensors, are indicated with D.

[0042] FIG. 2 illustrates a bridge circuit 11 positioned between a 24 Volts current source 12 for the supply of power to the three coils C1, C2 and C3 of the DC motor 3. It is to be noted that any suitable voltage can be used.

[0043] The bridge circuit includes a set of transistor switches T1-T6 that are made conductivenonconductive to controllably power supply the DC motor 3.

[0044] It is possible to make variations of the duration of conductivity of the transistor switches in order to apply force of different magnitudes by varying and by controlling transistor switches. It is possible to measure voltage in at least one of the conduits connected to the coils. A voltage detector can be active in respect of either one (or more than one) of the conduits associated with the coils C1-C3 and signals therefrom be passed on to the CPU.

[0045] It is possible to receive information from the DC motor and associated cables about its operation. If the motor is rotated, the rotational speed is directly proportional to the voltage. It is also possible to measure voltage which momentarily results in knowledge about rotational speed. For detection of rotational position of the rotor of the motor, a plurality of detectors is preferably being used. This gives information about throttle position.

[0046] The detectors are suitably stationary and for example co-operating with a ring or part of a ring being rotationally associated with the rotor or with one of the shafts, said ring having a great number of evenly distributed marks or holes. Monitoring the durations between pulses from three distributed mark or hole detectors results in information of position and rotational speed. There is also a possibility to detect rotor acceleration if required for some reason.

[0047] In the simplified flow chart in FIG. 3, an exemplary method sequence related to the invention is briefly illustrated. [0048] 13 indicates start of sequence. [0049] 14 indicates initiating DC motor to position throttle in desired position where the return spring is strained and stretched and verifying that throttle has reached the desired position. [0050] 15 indicates cutting current to the DC motor and initiating voltage measuring in at least one of the conduits being connected to the coils. [0051] 16 indicates monitoring throttle movements effected by the return spring by voltage measuring. [0052] 17 indicates evaluating monitored throttle movement pattern in relation to a stored exemplary movement curve. [0053] 18 indicates amending and adapting engine control values to established prevailing throttle actuation conditions. [0054] 19 indicates issuing a return spring condition message to the user and ending of sequence.

[0055] The sequence may be supplemented with additional steps and is repeated as required.

[0056] FIG. 4 shows a diagram over measured voltage as a function of elapsed time. The meandering curve, I.sub.m, represents momentary voltage signal output from a voltage detector associated with a coil conduit as a function of time (t). C.sub.mod represents a modulated curve thereof.

[0057] FIG. 5 shows a diagram over signal processed momentary rotational speed (n.sub.a) and voltage (u.sub.a) as a function of elapsed time (t). C.sub.ex represents an exemplary stored throttle rotational speed profile. As seen in FIG. 5, the rotational speed (n.sub.a) and voltage (u.sub.a) curves in the shown example have good conformity to the exemplary stored throttle rotational speed profile curve C.sub.ex. Hereby the condition of the return spring can be estimated to be as an exemplary return spring condition corresponding to the conforming stored profile. Furthermore, when a plurality of exemplary throttle rotational speed profile curves representing different return spring conditions are stored, the return spring condition is estimated to be as corresponds to the profile curve that most closely conforms to the measured profile.

[0058] The invention can be modified within the scope of the annexed claims. For example, the control circuitry can be laid out differently as can be the DC motor, for instance, the number of coils of the DC motor can be other than three.

[0059] The feature closed throttle is intended to include a case with totally blocked opening as well as a case with a certain minimum opening that might exist. With the feature opened throttle is intended the maximum opening achievable for the throttle in question.

[0060] Different kinds of sensors may be employed and they can be positioned in various places in association with the throttle assembly, for example close to the throttle itself.