Adjusting device for throttle valves

March 24, 1970 c. h. voges etal 3,502^000

ADJUSTING DEVICE FOR THROTTLE VALVES

Filed March 10, 1967

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United States Patent Office

3,502,000

Patented Mar. 24, 1970

3,502,000

ADJUSTING DEVICE FOR THROTTLE VALVES Christoph Heinrich Voges, 14 Algermissen Markt Str.

3201, Algermissen uber Hildesheim, Germany, and Gerd Johren, Kurt Schumacher Ring 29, Wolfsburg 5

318, Germany

Filed Mar. 10, 1967, Ser. No. 622,230

Claims priority, application Germany, Mar. 11,1966, 1,526,548

Int. Cl. F15b 13/042, 11/10; F02d 11/08

U.S. Cl. 91—47 1 Claim 1«

ABSTRACT OF THE DISCLOSURE

An adjusting device for the throttle valves for the car- ₁₅buretors of internal combustion engines operating in dependence on the underpressure of the suction pipe to the engine and effective independently of the altitude of the motor vehicle.

This invention relates to an adjusting device for throttle valves operating in dependence on the underpressure of the suction pipe of the engine of a motor vehicle. The fluctuation of the underpressure is due to changes in air pressure when altitude changes. 25

Pneumatic dashpots have been known which delay the return of the throttle into the closing position (idling position) by the fact that an arm of the control lever of the throttle valves will encounter a pestle or rammer of the dashpot shortly before the closing position of the throttle 30 valve. The pestle, at the same time, must shift a membrane clamped in the housing and it must drive out the air through a narrow opening from one of the housing chambers. In this manner it is to be avoided that the motor stops at a sudden release of the gas pedal. 35

Furthermore, devices of a similar mechanical construction have been known where the membrane is controlled in dependence on the underpressure. At the same time, beginning with a sudden underpressure, a limit is to be set for the movement of the throttle valve. In this manner, ⁴⁰the poisonous or objectionable part of the exhaust gas can be lowered or decreased. In these devices, also, provision has been made, as a rule, that a closing of the throttle valve at a sudden release of the gas pedal will take place in a delayed manner despite the then sudden reduction of 45 the underpressure.

The present invention is based on the realization that the underpressure adduced for control purposes is to a large extent dependent on the atmospheric pressure and that, in this manner, the control characteristic of the ad- 50 justing device will depend on the altitude at which the vehicle is used. As is well known, the atmospheric pressure drops with an increasing altitude of the locality and, in proportion with that, the absolute pressure of the suction pipe, correspondingly, the difference of these two pressures, 55 the underpressure of the suction pipe, is then also changed. If the atmospheric pressure, for example, drops from 1.0 to 0.8 atmosphere, then the underpressure of the suction pipe decreases, for example, from 0.5 to 0.4 atmosphere. Therefore, an adjusting device balanced as to the low 60 plains then becomes ineffective in the case of travel in high mountains. Vice versa, the closing movement of the throttle valve of a device adjusted in the mountains would be limited in an undesirably pronounced manner in the case of travel in the low plains, so that the underpressure 65 of the suction pipe would keep the throttle valve open even during idling or increase of the idling speed.

In order, therefore, to allow the adjusting device to become effective independently of the altitude of the locality, the proposal is made that the change of the underpressure, which is effective for the control, be compensated automatically in dependence on the atmospheric pressure with the assistance of an evacuated spring-loaded diaphragm box that is an aneroid case.

Further objects of the invention will be apparent from the following description when considered in connection with the accompanying drawing in which:

FIGURE 1 is a diagrammatic view showing the basic method of operation of an adjusting device of a throttle valve, and

FIG. 2 is; a cross sectional view of an adjusting device of a throttle valve with a pressure casing according to the invention connected thereon.

FIG. 1 shows the discharge part of a carburetor 1, with the throttle or butterfly valve 2 indicated, shown in a dashed line. The throttle valve is connected with an adjusting lever 3 which can be adjusted in a known manner by means of a Bowden cable 4 by the gas pedal which has not been shown. The normal idling position of the throttle valve 2 is determined by an adjustable stop screw 5, which can be screwed into an arm 3a of the adjusting lever 3 of the throttle valve and which cooperates with a stop 6 on the carburetor housing. The second arm 3b of the lever cooperates with a two-armed lever 7, one of the arms of which having been articulated to the pestle or rod 8 of a diaphragm device 9, the construction of which will be explained in connection with FIG. 2.

The adjusting device, attached to a cross member or right-angle arm 10 of the carburetor 1, has a housing 11, that has been subdivided into two chambers 13 and 14 by a diaphragm 12. The diaphragm 12 has been fixedly connected with the already described pestle or rod 8. When the engine is turned off, the diaphragm 12 is pressed by a spiral spring 15 into the left-hand final position shown in FIG. 2, as a result of which the rod 8, FIG. 1, is pushed into its right-hand final position, and, as a result thereof, the closing movement of the throttle valve 2 is not limited. The chamber 14 can be connected by a valve 16 with a chamber 17, which is in constant connection by a tube 18 with the suction pipe of the engine which latter is not shown. The chamber 17 has been closed on one side by a diaphragm 19, to which the valve body 16 has been attached. Normally, the diaphragm 19 is pressed into its right-hand end position by a spring 24, and in the case of underpressure in the suction pipe, it is made to bulge out toward the left, counter to the effect of the spring 24, and, in doing so, it will open the valve 16. As a result thereof, an underpressure will also build up in the chamber 14 and the diaphragm 12 is pressed toward the right, counter to the effect of the spiral spring 15, since the air of the atmosphere can flow into the chamber 13 through the annular opening 21. At the same time, the stop for the adjusting lever 3 of the throttle valve becomes effective. In the valve body 16, an opening 25 of a small diameter, has been provided through which air continuously flows into the chamber 14. This increase in pressure in the chamber 14 is only partially reduced by the opened valve 16, because the valve acts as a flow throttle, as a result of which the underpressure in chamber 14 becomes less than in the chamber 17. In the case of a sudden drop in the underpressure in the suction pipe, as a result thereof the valve 16 will, first of all, be closed, whereupon the underpressure in the chamber 14 is reduced only gradually by means of the opening 25. In the case of a sudden release of the gas pedal, therefore, the throttle valve 2 will reach its closed position in a delayed manner.

The description of the adjusting device for the throttle valve, as described, corresponds to the status of the prior art. As described in the introduction, the underpressure of the suction pipe, fluctuating with the altitude of the locality in which the vehicle travels, would however make the

3,502,000 efficiency of the device strongly dependent on the altitude. According to the invention, therefore, an additional evacuated spring-loaded diaphragm case (aneroid box) 22 has been provided, which exerts a force on the control valve 16 which is dependent on the dropping atmospheric pressure, which force corresponds to the force that is lacking on the membrane 19 in the case of a dropping underpressure of the suction pipe.

This force increases in the case of a dropping atmospheric pressure in the same measure in which the force _]0on the control diaphragm decreases because of the simultaneously decreasing underpressure in the suction pipe.

The sum of forces from the aneroid case 22 and the control diaphragm 19 remains constant in any atmospheric pressures, so that the adjusting device will respond inde- 15 pendently of altitude.

The adjustment of the point of response of the adjusting device is possible with the aid of the adjusting screw 23, by which an adjusting spring 24 below the control diaphragm 19 and the diaphragm case 22 can be tightened 20 in relation to one another.