Control Apparatus For The Idle Position Of A Throttle Valve For An Internal Combustion Engine

Abstract

Apparatus for automatic control of the throttle valve of an internal combustion engine comprises an adjusting mechanism for the throttle valve idle position operated by the negative pressure in an air inlet pipe via a negative pressure operated mechanism so that the idling position of the throttle valve can be adjusted. A temperature sensitive valve apparatus is operated by engine temperature and is interposed in a communicating passage between the inlet pipe and the negative pressure operated apparatus. The valve apparatus is so constructed that the negative pressure operated apparatus is brought into its operating condition by being in communication with the inlet pipe when the engine temperature is low, but is brought into inoperative condition by being in communication with the ambient air when the engine is heated to a predetermined temperature.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to apparatus for control of the operation of an internal combustion engine so that the idling position of the throttle valve at the time of engine starting is automatically adjusted according to change of engine temperature so that even when the engine temperature is low, smooth operation and rapid heating of the engine can be effected.

2. Prior Art

In conventional internal combustion engines the idling position of the throttle valve at the time of engine starting is so controlled as to be constant regardless of engine temperature. Thus, idling speed varies with rise and fall of engine temperature, especially when the engine temperature is low and the idling speed is lowered due to the large resistance of a movable member. Accordingly warming of the engine is delayed and there is the danger that the engine may stall in some conditions of operation.

SUMMARY OF THE INVENTION

This invention contemplates an arrangement wherein the idling position of the throttle valve at the time of engine starting is automatically adjusted in relation to engine temperature so that when the engine temperature is low, the throttle valve is opened more at idle to provide a faster engine operation, whereby a larger output power can be obtained and engine heating can be rapidly effected.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side view, partly in section, of one embodiment according to this invention; and

FIG. 2 is a side view, partly in section, of a modified embodiment according to this invention.

DETAILED DESCRIPTION

Referring to FIG. 1 therein is seen an air inlet pipe 1, which is connected at its left end to an internal combustion engine; the pipe 1 is provided with an adjusting mechanism a for controlling the degree of opening of a throttle valve 2 during engine idling. The mechanism a is connected to a negative pressure operated apparatus b which is operated by the suction prevailing in the inlet pipe 1. A temperature sensitive valve apparatus c is operated in response to engine temperature and is interposed between the pipe 1 and the negative pressure operated apparatus b. The valve apparatus c serves to connect the apparatus b selectively to the interior of the pipe 1 or the external air.

The construction of the adjusting mechanism a will next be described in detail.

The outer end of a supporting shaft 3 of the throttle valve 2 carries the middle portion of a swingable rod 4 secured thereto and the base end of a rotatable arm 5 rotatably supported thereon. A pin 6 projecting from the front end of the swingable rod 4 is loosely mounted with play in a circular opening 7 in the rotatable arm 5.

A tension spring 8 is connected between the swingable rod 4 and the rotatable arm 5 and serves to cause the swingable rod 4 to return to an initial position to keep the throttle valve 2 in an open idling position at the time of engine warming operation. A tension spring 10 stronger than the tension spring 8 is connected between the rotatable arm 5 and a supporting member 9 secured to the pipe 1. This spring 10 serves to rotate the rotatable arm 5 about the supporting shaft 3 in clockwise direction, whereby the front end of the rotatable arm 5 is brought into abutment with an adjusting screw 11 screwed to the supporting member 9 and controlling the degree of opening at idle.

A throttle valve operating cable 12 is connected to the front end of the rotatable arm 5, so that when the rotatable arm 5 is rotated in counterclockwise direction by pulling cable 12, the swingable rod 4 is also rotated in the same direction through the engagement between the circular opening 7 and the pin 6, whereby the throttle valve 2 secured to the swingable rod 4 can be opened and thus ordinary opening and closing of the throttle valve 2 in an ordinary engine operation can be effected.

The construction of the negative pressure operated apparatus b will next be described in detail.

A negative pressure chamber 14 formed within a casing 13 is in communication with the valve apparatus c, and a diaphragm 16 is provided at the interior thereof. The swingable rod 4 is connected to the lower end of a rod member 17 connected to diaphragm 16, and a return spring 18 is interposed between the casing 13 and the diaphragm 16.

The construction of the temperature sensitive valve apparatus c will next be described in detail.

A temperature sensitive chamber 19 is formed at a suitable portion of the engine main body such as at a crankcase, cylinder head or the like, and the interior of the temperature sensitive chamber 19 is in communication through a conducting tube 20 with the interior of the pipe 1 and is in communication through a conducting tube 15 with the interior of the negative pressure chamber 14 of the apparatus b. Further the chamber 14 is in communication through a conducting tube 21 with an air cleaner 22 connected to external ambient air. A duct 23 connected to the intake pipe 1 and a duct 24 connected to the air cleaner 22 are arranged to face one another, and a valve 26 is formed at the front end of a temperature sensitive member, such as a bimetallic strip 25. The strip 25 is supported by the wall of the temperature sensitive chamber 19 and projects between ducts 23 and 24, so that the valve 26 can close the duct 24, as illustrated, when the temperature of the engine E is low. The bimetallic strip 25 is bent downwards and the duct 23 is closed when the engine temperature is elevated.

Since, under the condition where the engine is cold, the duct 24 is closed and the interior of the temperature sensitive chamber 19 is intercepted from its communication with the external air, if the engine is started in this condition, the negative pressure within the pipe 1 acts on the interior of the negative pressure chamber 14 of the negative pressure operated apparatus b to lift the rod member 17 and rotate the swingable rod 4 in the counterclockwise direction, whereby the throttle valve 2 secured thereto is opened to a degree suitable for idling speed at the time of engine starting. Since, in this case, the pin 6 secured to the swingable rod 4 is loosely mounted with play in the circular opening 7 of the rotatable arm 5, the swingable rod 4 can be rotated independently of the rotatable arm 5. When the engine is in an idling operation and is heated, the bimetallic strip 25 is bent downwards to open the duct 24 and, at the same time, close the duct 23, so that the interior of the negative pressure chamber 14 is in communication with the external air through the air cleaner 22 and, at the same time, is intercepted from its communication with the interior of the pipe 1. Thereby the rod member 17 is lowered by the action of the return spring 18 and the swingable rod 4 is returned to its initial position by the action of the tension spring 8. Thus the throttle valve 2 is turned to its open position at idling when the engine is heated.

If the engine maintains a temperature greater than a predetermined value, the valve 26 continues closing the duct 23 and accordingly the negative pressure in pipe 1 does not act on the negative pressure operated apparatus b even at the time of engine starting, so that the throttle valve 2 is not opened beyond the ordinary open idling position.

Thus, according to this invention, at the time of engine starting, the throttle valve is automatically adjusted to a fast idling open position when the engine is cold and thus engine operation is smooth and engine heating can be achieved rapidly and smoothly. The rotating force for adjusting the throttle valve to a fast idling open position can be obtained by utilizing the large intake negative pressure of the engine, so that the adjustment can be positively effected. The temperature sensitive member such as the bimetallic strip is used only for opening and closing control of the valve, so that large force is not applied thereto and the control thereby can be positively effected while the apparatus can be small in size.

Additionally, since the temperature sensitive valve apparatus c is connected by conduits between the inlet pipe 1 and the negative pressure operated apparatus b the attaching position of valve apparatus c can be freely selected and the temperature sensitive valve can be provided at a location at which the optimum temperature of the engine can be detected. Thus the engine temperature can be sensitively sensed and the attaching of apparatus c can be facilitated.

In the modified embodiment of FIG. 2 the negative pressure acting on the negative pressure operated apparatus b can be adjusted continuously with change of engine temperature, whereby the adjustment of the idling position of the throttle valve can be accurately effected continuously and without steps. This modified embodiment differs from the first embodiment in the construction of the temperature sensitive valve apparatus c'.

In the temperature sensitive valve apparatus c', a fixed orifice 28 is interposed in the portion communicating with the pipe 1, and the air cleaner 22 and the temperature sensitive chamber 19 are in communication with one another through duct 24' and a fixed orifice 27. A needle valve 26' is secured to the end of the bimetallic strip 25 and faces the duct 24' so as to form a variable orifice 29 by the cooperation of needle valve 26' and duct 24'. Thus the fixed orifices 27, 28 cooperate to keep the pressure within the temperature sensitive chamber 19 substantially constant regardless of change of intake negative pressure and the pressure within the chamber 19 is changed only by change in the size of the variable orifice 29.

If the engine temperature is low, the bimetallic strip 25 is bent downwards to throttle the variable orifice 29, and if the engine temperature is high, the bimetallic strip is bent upwards to open the orifice 29. Accordingly, when the engine temperature is low, a negative pressure force acts on the negative pressure operated apparatus b, and as the engine temperature rises, the negative pressure force is gradually decreased, and thus the negative pressure force acting on the negative pressure operated apparatus b is adjusted continuously without steps and thereby the fast idling open position of the throttle valve is also adjusted without steps in accordance with the change of engine temperature.

Thus, according to the modified embodiment of this invention, in addition to the advantages of the first embodiment, the intake negative pressure force acting on the negative pressure operated apparatus can be continuously adjusted without steps with change of engine temperature, so that the fast idling open position of the throttle valve is also adjusted without steps in accordance with the engine temperature change and thus the adjustment of the fast idling open position can be effected more accurately and smoothly.

Claims

What is claimed is:

1. Control apparatus for the idle position of a throttle valve in an air inlet pipe of an internal combustion engine, said apparatus comprising first means coupled to the throttle valve to adjust the idle position thereof, second means operatively coupled to the first means to operate the same, the second means including a mechanism operated by negative pressure, and third means coupled to the second means and to the air inlet pipe and to ambient atmosphere and including a valve member sensitive to engine temperature to selectively connect the mechanism of the second means to the inlet pipe or the ambient atmosphere.

2. Control apparatus as claimed in claim 1 wherein the mechanism of the second means comprises a chamber connected to the third means, a diaphragm in said chamber movable therein according to the pressure in said chamber, said pressure being a function of the position of the valve member, and an operating member connecting the diaphragm and the first means.

3. Control apparatus as claimed in claim 1 wherein said third means has first and second ducts respectively connected to the ambient atmosphere and the inlet pipe, and a chamber connected to the second means, the first and second ducts opening into said chamber, said valve member comprising a temperature sensitive member in said chamber for closing the first duct when the engine is cold and the second duct when the engine has reached a predetermined heated state.

4. Control apparatus as claimed in claim 3 wherein said temperature sensitive member is a bimetallic strip.

5. A control apparatus as claimed in claim 3 comprising means for continuously adjusting the idle position of the throttle valve between the conditions when the engine is cold and it has reached its predetermined heated state.

6. A control apparatus as claimed in claim 5 wherein said means for continuously adjusting the idle position of the throttle valve comprises means for gradually varying the negative pressure supplied to the second means from the inlet pipe.

7. A control apparatus as claimed in claim 6 wherein said means for gradually varying the negative pressure supplied to the second means comprises a variable orifice means between the valve member and the first duct for providing varying cross-section for flow of ambient air as the valve member moves from the first duct towards the second duct.

8. A control apparatus as claimed in claim 7 wherein said means for gradually varying the negative pressure supplied to the second means comprises fixed orifices between said chamber and the inlet pipe and the ambient atmosphere.

9. A control apparatus as claimed in claim 2 wherein said first means comprises a support shaft for the throttle valve, and a swingable rod secured to said support shaft and coupled to said operating member.

10. A control apparatus as claimed in claim 9 wherein said first means further comprises a rotatable arm rotatably mounted on the support shaft, a control cable connected to said rotatable arm to operate the throttle valve, a tension spring between the rotatable arm and the swingable rod, and a connection with play between the rotatable arm and swingable rod.