THROTTLE BODY CONTROL ARRANGEMENT

Abstract: A throttle body butterfly valve controlled by electrical signals in a drive-by-wire arrangement includes a mechanical coupling cable (9) arranged to close the throttle if the valve is locked in the open throttle condition

Description: This invention relates to a fail safe control arrangement for a throttle body butterfly valve. Conventionally throttle body butterfly valves on automobiles are controlled by a throttle control member, for example an accelerator pedal, by way of a direct mechanical connection in the form of a cable or lever arrangement, depression of the accelerator causing the mechanical connection to pull the butterfly valve into an open throttle condition, the butterfly valve being returned to a relatively closed throttle condition by means of a spring when the accelerator pedal is released. Recently a new control arrangement has been proposed in which the butterfly valve is controlled by means of electrical signals transmitted over a transmission wire in response to operation of a throttle control member, such an arrangement being known (at least in the U.S.A) as a "drive by wire" arrangement. The electrical signals transmitted to the throttle body control an electric motor which operates the butterfly valve by way of a gear box, the motor serving to urge the butterfly valve in both the open throttle and closed throttle directions. A difficulty which can arise with such a drive by wire control arrangement is that in the event of a fault occurring the butterfly valve can become locked in an open throttle condition, this being particularly the case if the fault is seizure of the gear box or motor operating the butterfly valve. It is known to provide a "drive-by-wire" butterfly valve control arrangement in which an electromagnetic clutch is arranged to be able to couple a throttle control member and the operating member of a butterfly valve. On detection of a fault in the drive by wire control arrangement, the electromagnetic clutch causes the mechanical coupling of the throttle control member and the operating member. Movement of the throttle control member is then able to cause movement of the operating member by mechanical means rather than by means of the drive by wire arrangement. This type of arrangement is disclosed in JP-A-59153945. In the JP-A-59-153945 arrangement, if the fault is the seizure of the motor which operates the butterfly valve, it may not be possible to close the butterfly valve even when the throttle control member and the operating member are coupled together. A vehicle fitted with such a control arrangement under these circumstances is likely to become out of the control of the driver. According to this invention there is provided a butterfly valve control arrangement according to claim 1. With the control arrangement of this invention in the event of a fault occurring in the normal drive by wire arrangement the mechanical coupling means which during normal operation serves no purpose, provides a coupling between the throttle operating member, for example the accelerator pedal, and the butterfly valve, which on release of the throttle operating member and its consequential return to a rest condition serves to pull the butterfly valve into a closed throttle condition, such movement of the butterfly valve being possible because of the breaking of the clutch coupling in the control arrangement. Thus, the mechanical coupling means which can be a cable, serves to pull the butterfly valve into a closed throttle condition in the event of a fault. Preferably the drive member and the driven member are coupled by means of a clutch having complementary engaging surfaces which are urged together by urging means such as a compression spring, and which in the event of a fault movement of the driven member in the throttle closing direction is arranged so that the members are moved apart against the action of the urging means to break the coupling between the drive member and the driven member. The engaging surfaces preferably comprise a pointed concave surface and a corresponding pointed convex surface; preferably the included angle ranges from about 100° to about 170°. The faces may be shaped e.g. radiused, for ease of coupling and decoupling. The control arrangement of the invention may be powered by an electric motor and an associated gear box but the gear box may be omitted and the drive member is then directly connected to the spindle of the electric motor. This invention will now be described by way of example with reference to the drawings, in which:- Figure 1 is a top plan view of an arrangement according to the invention; and Figure 2 is a part vertical sectional view through the arrangement of Figure 1. The arrangement comprises a drive member 1 in the form of a lever mounted for rotation about the control vertical axis 10 of the arrangement, the lever l being moved in response to electrical signals transmitted under the control of a throttle control member (not shown) by means of an electric motor and an optional associated gear box (neither shown). The arrangement also comprises a driven member 3 in the form of a spindle mounted for rotation about the axis 10, the spindle being connected to a throttle body 100 to control the butterfly valve position. The drive member 1 is coupled to the driven member 3 by means of a clutch 2 comprising a first member 4 mounted on the drive member 1 and having a pointed convex face which engages in a corresponding pointed concave face of a second member 5 mounted on the driven member 3. A compression spring 6 mounted about the driven member 3 and acting between the first clutch member 4 and a fixed collar 11, serves to hold the clutch members 4 and 5 in engagement such that movement of the drive member 1 in response to electrical signals transmitted by the throttle control member causes corresponding movement of the driven member 3 and thus appropriate control of the butterfly valve position of the throttle body 100. The rotating surfaces of the clutch members 4 and 5 are shaped such that the drive member 1 can rotate the driven member 3 in either direction when the clutch is engaged, and such that if the driven member 3 is used as a drive member and is urged in the throttle closing direction the clutch member 4 is urged away from the clutch member 5 against the action of the spring 6 thereby allowing the required movement of the driven member 3 to take place and move the butterfly valve within the throttle body 100 to a closed throttle condition even if the drive member 1 cannot move, for example because the associated motor or gear box has become jammed. Movement of the driven member 3 as a drive member in the event of a fault is provided by means of a cam 8 mounted on the body 7, which cam 8 is connected by a mechanical coupling means in the form of a cable 9 which is connected to the cam 8 and to the spring loaded throttle control member associated with the throttle body 100. In the event of a fault in the normal operation of the throttle body butterfly valve control arrangement, the throttle control member is released to move the butterfly valve to the throttle closed condition, the control member pulling on the cable 9 which thus rotates the driven member 3 by way of the cam 8 as required to move the butterfly valve to the throttle closed condition, the clutch 2 being opened to break the connection between the driven member 3 and the drive member 1 as described above. In normal operation of the control arrangement the cable 9 does not interfere with the control of the throttle body 100 by the electrical signals from the throttle control member. The control arrangement above described can be set up to provide for limited opening of the throttle butterfly valve of the throttle body while a fault condition exists in order to give a 'limp home' capability. Because of the engagement of the facing surfaces of the first and second members, in the event of a brief fault condition the control arrangement will reset itself to the normal operating position.

Claims: A butterfly valve control arrangement comprising a drive member (1) adapted to be controlled by electrical signals transmitted under the control of a throttle control member; a driven member (3) for connection to the butterfly valve, and mechanical coupling means (9) adapted to be connected to the throttle control member, characterised in that a mechanical clutch (2) connects the drive member (1) to the driven member (3) such that in normal operation control of the drive member (1) by said electrical signals effects corresponding control of the driven member (3) and thus of the butterfly valve, said mechanical coupling means (9) being connected to the driven member (3) and, when connected to the throttle control member, being operative in the event that movement of the throttle control member in a throttle closing direction does not produce corresponding control of the butterfly valve by means of said electrical signals, to move the driven member (3) in the throttle closing direction and simultaneously to break the clutch coupling (2) between the drive member (1) and the driven member (3). An arrangement according to Claim 1 characterised in that the mechanical coupling means comprises a cable (9). An arrangement according to Claim 2 characterised in that the cable (9) extends between a cam (8) associated with the driven member (3) and the throttle control member. An arrangement according to Claim 1, 2 or 3 characterised in that the mechanical clutch (2) comprises a first member (4) mounted on the drive member (1) and a second member (5) mounted on the driven member (3) and a spring (6) serving to urge the first and second clutch members (4, 5) into engagement, the first and second clutch members (4, 5) having co-operating surfaces which in normal operation provide a coupling between the drive member (1) and the driven member (3) such that movement of the drive member (1) causes corresponding movement of the driven member (3), and which in the event of a fault and movement of the driven member in the throttle closing direction by the mechanical coupling means cause movement of the first clutch member (4) away from the second clutch member (5) against the action of the spring (6) thereby breaking the coupling between the drive member (1) and the driven member (3). An arrangement according to any preceding claim characterised in that the electrical signals control the drive member (1) by way of an electric motor, and optionally a gear box. An arrangement according to any preceding claim characterised in that the movement of the drive member (1) and the movement of the driven member (3) is rotary, the movements being about a common axis (10).

Inventors: PASCALL, KEITH LESLIE
Applicants: LUCAS INDUSTRIES PUBLIC LIMITED COMPANY
Application year: 1987
Main classification: F02D11
IPC codes: F02D11