US3927657A

US3927657A - Throttle return systems for carburettors

Info

Publication number: US3927657A
Application number: US454834A
Authority: US
Inventors: Francois Mennesson
Original assignee: Societe Industrielle de Brevets et dEtudes SIBE
Current assignee: Societe Industrielle de Brevets et dEtudes SIBE
Priority date: 1973-04-05
Filing date: 1974-03-26
Publication date: 1975-12-23
Anticipated expiration: 1992-12-23
Also published as: FR2224644A1; FR2224644B1

Abstract

The shaft of a carburettor throttle is provided with a first return torsion spring one end of which abuts a lug of the carburettor body. A second return spring is stressed between the lug and the stationary end of the first spring. If the first spring fails, the second spring may exert a return force on the throttle which is almost as high as that of the first spring.

Description

United States Patent ['91 Mennesson THROTTLE RETURN SYSTEMS FOR CARBURETIORS Francois Mennesson, N anterre, France Societe Industrielle de Brevets et dEttrdes S.I.B.E., Neuilly-sur-Seine, France Filed: Mar. 26, 1974 Appl. No.: 454,834

Inventor:

[73] Assignee:

Foreign pp ication Priority Date p 3 Franee 73.!2369 U18, Chm... 123/198 D; 123/198 DB; 125/142; 74/513: 180/82 In c l' iiliilll i!llull II I [58] Field 123/198 D, [98 DB, 142, 123/198 R; 74489.2, 96, 513; 180/82, 82.1

Retereneee Cited UNITED STATES PATENTS 3326.919 12/19' MaeMillen l23/l98 D8 1 Dec. 23, 1975 3.698.372 10/1972 Eshelman et alt 123/198 D X 3,699,943 10/1972 Eshelman 123/198 DB 3,704,635 lZ/I972 Eshelman 123/195 D X 3,760,786 9/1973 Mlrlh 180/82 R Primary Examiner-Charles J. Myhre Assistant Examiner-Ira S. Lazarus Attorney. Agent. or Firm-Stevens. Davis, Miller & Mother 2 Ciaims, 4 Drawing Figures U.S. Patent Dec. 23, 1975 Sheet 1 of2 3,927,657

U.S. Patent Dec. 23, 1975 Sheet 2 of2 3,927,657

THROTTLE RETURN SYSTEMS FOR CARBURETTORS BACKGROUND AND SUMMARY OF THE INVENTION The invention relates to internal combustion engine carburettors of the kind which comprise, in an intake manifold, a throttling member carried by a rotary shaft and connected to an accelerator control which enables the driver to open such member against the force of resilient return means which act on such shaft and tend to return the throttling member into a minimum opening position corresponding to engine idling.

Such resilient return means have been formed by a single spring which is subjected to a deforming force when the driver opens the throttling member. Safety requirements now lay down that at least two separate return springs must be provided each of which is able to return the throttling member to its idling position. The simplest method would consist in disposing the two springs in parallel, but this would result in practice in doubling the force which the driver must exert to open the throttling member, since each spring must exert force adequate to enable it to reclose the throttling member on its own i.e., if the other spring breaks.

It is an object of the invention to provide such return means using two springs without however appreciably increasing the force required to open the throttling member and without substantially increasing the complexity of the construction.

For this purpose, there is provided, in a carburettor for internal combustion engine having a throttle member secured to a rotary shaft and adapted to be angularly moved with respect to the carburettor body by control means, resilient return means for biasing said throttle member toward a minimum opening position, comprising: a first torsional return spring having a first end retained in fixed relation with respect to the carburettor body and its other end operatively connected to said shaft for exerting a return force on said shaft; a second torsion spring having a first end which is retained in fixed relation with respect to the carburettor body and its other end in abutting relation against said first end of the first spring which retains said first spring in stressed condition; and abutting means nonrotatably connected to said throttling member and located on the path followed by said other end of the second spring when clear from abutment against the first spring.

Under normal operating conditions only the first spring exerts a return force. If the first spring fails, the second end of the second spring loses its bearing and starts to co-operate with the abutting means connected to the throttle member shaft to exert a return force on the throttle member.

In a particular embodiment, the two torsion springs are coil springs wound on the throttling member shaft each on one side of a lever secured to the shaft and bearing two pins substantially parallel with the shaft and turned towards the two springs respectively, and the carburettor body has a projecting lug acting as a stop for the first ends of the two springs; one of the pins normally acts as a bearing for the second end of the first spring; the other pin constitutes the said abutting means non-rotatably connected to the throttling member shaft.

The invention will be better understood from the following description with reference to the accompanying drawings, such description and drawings relating to a preferred embodiment.

SHORT DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 show, sectioned along the line Il in FIG. 2 and the line II-Il in FIG. 1 respectively, the lower part of a carburettor whose throttling member is completely opened.

FIG. 3, similar to FIG. 2, shows the same carburettor with its throttling member in its minimum opening position.

FIG. 4 shows, similarly to FIG. 3 but with a slight offsetting of the sectional plane, the same carburettor in which only the second torsion spring is in operation.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGS. 1-4, there is shown the body 1 of a carburettor of downdraught type whose conventional elements are not illustrated. An inlet manifold 2 extends through the body and contains a throttling member or butterfly 3 secured to a rotary shaft 4 by screws 5. One of the ends of the shaft 4 is screw-threaded to receive a nut 6 which retains a lever 7 which is connected to an accelerator control (not shown).

A lever 8 connected to the shaft 4 bears a pin 9 parallel therewith which acts as a bearing for one end 16 of a first helical torsion spring 10. The other end I5 of the spring 10 bears against a projecting lug ll integral with the carburettor body 1. When the butterfly 3 is opened (counterclockwise, from the position illustrated in FIG. 3 to that illustrated in FIG. 2), the resulting movement of the pin 9 winds the spring 10 around the shaft 4, so that the spring biases the butterfly towards its closed position.

The construction described until now is conventional. The shaft 4 carries a second helical torsion spring 12 one end 13 of which bears against the lug II, the other end portion 14 being bent (as appears on FIG. 1) so that it normally bears against the end portion 15 of the spring 10. The lever 8 carries a second pin 17 disposed on the path of the end I4 of the spring 12 when the end portion 14 is not retained by the end portion 15 of the first spring 10.

In the particular embodiment illustrated, the

springs

10 and 12 are disposed each on one side of the lever B, the spring 10 being closest to the frame I. The pin 9 projects towards the body I and the pin 17 in the opposite direction. The end portions I3, 14 (before its bend), l5 and 16 are directed tangentially with respect to the helical portion of the springs l0, 12. The bend of the end portion 14 is located level with the lever 8 (FIG. I).

The return means operate as follows. During idling (FIG. 3), under normal conditions, the spring 10 alone exerts a closure torque on the shaft 4 of the butterfly 3 via its end portion 16, the pin 9 and the lever 8. The spring 12 does not act on the shaft 4, since its two ends I3, 14 are retained by stationary parts. The torsion force of the spring 12 is so selected that the force exerted by its end portion 14 on the end portion I5 of the spring 10 does not move the end I5 clear of abutment against the lug 11. If the butterfly 3 is opened (i.e., moved toward the angular position illustrated in FIGS. 1 and 2), the force to be overcome is therefore only that of the spring I0.

lffor any reason the spring 10 is broken (as shown on FIG. 4, on which the spring I0 has been omitted), the end I4 of the spring 12 is released and moves into abutment with the pin 17 of the lever 8, thereby exerting a closure torque on the butterfly 3. If the throttle is then opened, the force to be overcome is only that of the spring 12.

Conversely, if the spring 12 gets broken, the spring continues to operate as described hereinbefore.

As a result, there is obtained a simple return system having two separate springs whose forces are exerted separately and not simultaneously, so that the force needed to open the butterfly is not appreciably increased.

I claim:

1. In a carburettor for an internal combustion engine having a throttle member secured to a rotary shaft and adapted to be angularly moved with respect to the carburrettor body by control means, resilient return means for biasing said throttle member toward a minimum opening position, comprising: a first helical torsion return spring wound around the shaft and having a first end retained in fixed relation with respect to the carburettor body and its other end operatively connected to said shaft for exerting a return force on said shaft; a second helical torsion spring wound around the shaft and having a first end which is retained in fixed relation with respect to the carburettor body and its other end in abutting relation against said first end of the first spring which retains said second spring in stressed condition; a lever; and abutting means carried by said lcver, said abutting means being non-rotatably connected to said throttle member and located on the path followed by said other end of the second spring when clear from abutment, whereby said second spring unwinds upon breakage of said first spring and exerts on said abutting means a force tending to move said throttle member toward its closed condition.

2. A carburettor as set forth in claim I, wherein the two torsion springs are wound on opposite sides of said lever which carries two pins substantially parallel with the shaft and turned towards the two springs respectively, and the carburettor body has a projecting lug acting as a bearing for the first ends of the two springs, one of the pins acting as a bearing for the second end of the first spring, and the other pin comprising said abutting means.

Claims

1. In a carburettor for an internal combustion engine having a throttle member secured to a rotary shaft and adapted to be angularly moved with respect to the carburrettor body by control means, resilient return means for biasing said throttle member toward a minimum opening position, comprising: a first helical torsion return spring wound around the shaft and having a first end retained in fixed relation with respect to the carburettor body and its other end operatively connected to said shaft for exerting a return force on said shaft; a second helical torsion spring wound around the shaft and having a first end which is retained in fixed relation with respect to the carburettor body and its other end in abutting relation against said first end of the first spring which retains said second spring in stressed condition; a lever; and abutting means carried by said lever, said abutting means being non-rotatably connected to said throttle member and located on the path followed by said other end of the second spring when clear from abutment, whereby said second spring unwinds upon breakage of said first spring and exerts on said abutting means a force tending to move said throttle member toward its closed condition.

2. A carburettor as set forth in claim 1, wherein the two torsion springs are wound on opposite sides of said lever which carries two pins substantially parallel with the shaft and turned towards the two springs respectively, and the carburettor body has a projecting lug acting as a bearing for the first ends of the two springs, one of the pins acting as a bearing for the second end of the first spring, and the other pin comprising said abutting means.