GB1560092A

GB1560092A - International combustion engines

Info

Publication number: GB1560092A
Application number: GB27879/76A
Authority: GB
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1975-07-08
Filing date: 1976-07-05
Publication date: 1980-01-30
Also published as: BR7604466A; JPS5244967B2; BE843804A; DE2630180A1; ES449571A1; NL7607392A; AR209660A1; AU1509076A; CS200153B2; IT1066574B; FR2317515B1; DD127080A5; NL168299B; CH615248A5; FR2317515A1; JPS526831A; NL168299C; CA1044092A; SE7607690L

Abstract

In order to retard the closing movement of the throttle valve (2) without significantly impairing the running of the engine, this closing movement is controlled as a function of the vacuum upstream and downstream of the throttle valve (2). In doing this, an air feed device automatically feeds additional air to the feed duct (1) downstream of the throttle valve (2) when the vacuum there falls sharply. This device has an additional air inlet (18) arranged downstream of the throttle valve (2), which inlet is connected by way of an inlet line (19) to a control valve (20) preloaded in the closing position. The latter is designed so that in the event of a sharp increase of the vacuum on the inlet (18) it rapidly opens in order to immediately counteract this increase by an additional air feed. <IMAGE>

Description

(54) IMPROVEMENTS RELATING TO INTERNAL COMBUSTION ENGINES (71) We, HONDA GIKEN KOGYO KABUSHIKI KAISHA, a Japanese body corporate ofNo. 27-8. 6-chome, Jingumae, Shibuya-ku, Tokyo, 150 Japan, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to intake control apparatus for an internal combustion engine for a motor vehicle. It is known that sudden deceleration in engine speed results in an increase in pollutants discharged into the atmosphere with the engine exhaust gases.

However, when attempts have been made to correct this undesirable result by retarding the closing action of the throttle valve in the engine intake passage, another difficulty is encountered in that the desirable braking effect of the engine to reduce vehicle speed is adversely affected. It is an object of the present invention to provide intake control apparatus which maintains the discharge of pollutants into the atmosphere within acceptable limits, whilst at the same time retaining a sufficient portion of the desirable engine braking effect.

According to the invention there is provided intake control apparatus for an internal combustion engine, comprising a throttle valve mounted in an intake passage, and control means for regulating closing movement of said throttle valve under the influence of the degree of vacuum both upstream and downstream of the throttle valve, wherein there is provided air inlet means arranged to automatically admit additional air into said intake passage downstream from the throttle valve when there is a sudden increase in the degree of vacuum in the intake passage downstream from the throttle valve.

Preferably the said air inlet means comprises an air inlet passage having a control valve therein, said control valve being arranged to open quickly when there is a said sudden increase in the degree of vacuum, but to close relatively slowly when said degree of vacuum is subsequently reduced.

Preferably the said control valve has a movable valve element, pressure responsive means arranged to move said valve element between open and closed positions, said pressure responsive means including a movable member subjected on one side to pressure in said air inlet passage, a closed chamber on the other side of said movable member, and valve means on the movable member acting to restrict flow from the closed chamber to the air inlet passage while permitting relatively unrestricted flow in the opposite direction.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a sectional schematic diagram of an intake control apparatus according to the invention; and Figure 2 is a graph showing closing characteristics of the throttle valve of such apparatus.

Referring to the drawings, the apparatus comprises an intake passage 1 for connection to an internal combustion enginge, not shown. A throttle valve 2 is mounted in the passage on a shaft 2a and a venturi 3 is located upstream from the throttle valve 2.

Control means including a dash pot generally designated 4 operates in association with the throttle valve 2 to limit the speed of movement of the throttle valve near its minimum opening position. This dash pot 4 includes a flexible diaphragm 5 which forms one wall of a vacuum chamber 7. The vacuum chamber 7 is connected to atmosphere through a restricted passage 6 in the form of a small jet.

The diaphragm 5 is connected to a rod 8 which in turn is pivotally connected to an arm 9. The arm 9 is mounted to turn about the axis of the throttle valve shaft 2a. The dash pot 4 contains an abutment 10 which limits retracting movement of the rod 8. A projection 2b is fixed to the throttle valve shaft 2a and is engageable with the pivoted arm 9.

The parts are proportioned so that closing movement of the throttle valve 2 within a few degrees of its minimum opening position is accompanied by movement of the rod 8 and the diaphragm 5. The connection between the parts 2b and 9 may therefore be described as an angular lost-motion connection. The diaphragm 5 never resists opening movement of the throttle valve 2.

A first vacuum tapping port 11 of relatively small diameter, for example about 1 mm, is provided at the side of the intake passage 1 slightly upstream of the adjacent portion of the throttle valve 2 at its minimum opening position. This vacuum port 11 is connected to the vacuum chamber 7 via a check valve 12 in a passage 13. When the engine is running and when the throttle valve 2 is near its minimum opening position, a relatively high degree of vacuum is produced in the passage 13, so that check valve 12 opens and the diaphragm 5 is caused to move in a direction to open the throttle valve 2.

At one side of the intake passage 1 and downstream of the throttle valve 2 a second vacuum tapping port 14 is provided which is connected to the vacuum chamber 7 through a second vacuum passage 17. In this second vacuum passage 17 is located a speed responsive valve 15a that opens by detecting relatively high rpm of the engine. Also positioned in this passage 17 is a vacuum response valve 15b that opens under a high degree of vacuum, and a check valve 16.

Accordingly, when the dash pot 4 controls closing operation of the throttle valve 2, vacuum that is generated on the downstream side of the throttle valve 2 acts through the second vacuum port 14 and second vacuum passage 17 to said vacuum chamber 7 to tend to open the throttle valve. Decrease of engine speed or reduction in the degree of vacuum closes the passage 17. Thereafter the dash pot 4 performs its normal operation to control the closing characteristics of throttle valve 2.

If the intake control apparatus were to comprise only the mechanism described above, without the means for supplying additional air to be described below, the closing characteristics of the throttle valve 2 would lie, as shown by line A in Figure 2, between area B at the upper side where the braking action of the engine is ineffective, and area C at the lower side where exhaust pollutants reach unacceptable levels. However, if area C at the lower side can be further displaced downward to area D, for instance, line A can be shifted to line A' for more effective engine brake action and improved driveability. Such a shift to area D can be accomplished by introducing atmospheric air into the intake passage 1 during sudden deceleration.

Therefore, at the side of the intake passage 1 and at a location downstream from the throttle valve 2, an opening 18 is provided which is connected to atmosphere through an air inlet passage 19. A control valve 20 is provided in the air passage 19 and this control valve 20 opens automatically when the degree of vacuum at the opening 18 increases suddenly, and thereby allows atmospheric air to enter the intake passage 1 through the opening 18. The control valve 20 is connected to a movable member 23a mounted on an annular flexible diaphragm 23. A vacuum chamber 21 is formed on one side of the diaphragm 23 and a closed chamber 24 is formed on the other side. A flap 26 mounted on the movable member 23a serves as a check valve for the opening 23b. A small orifice 25 is provided in the flap 26 in alignment with the opening 23b.The air passage 19 is connected directly to the vacuum chamber 21 and is also connected to control valve 20 through a ball check valve 27 which affords protection to the valve 20 in the case of backfire.

In operation, sudden increase in the degree of vacuum at the opening 18 causes the diaphragm 23 to open the valve 20, the flap 26 remaining closed. Atmospheric air may then pass the ball check valve 27 through passage 19 and into the intake passage 1 through the opening 18. Continued deceleration allows air to pass from the closed chamber 24 to the vacuum chamber 21 through the orifice 25, to reduce the rate of air input through opening 18. When deceleration is discontinued, a spring 22 moves the diaphragm 23 to close the valve 20, and the flap 26 opens to permit flow of air from the chamber 24 through the opening 23b into the vacuum chamber 21.

The control valve 20 is placed at a location higher than that of the opening 18; a location 80 mm or higher, for instance, prevents fuel in the air-fuel mixture from collecting in the control valve 20.

Associated with the restricted passage 6 is a solenoid operated valve 29 which is connected through the engine ignition switch 30 to the battery 31. When the ignition switch is closed the solenoid is energised and the valve 29 is dosed. When the ignition switch is opened the valve 29 is opened by its spring so as to admit atmospheric air into the vacuum chamber 7. Thus when the engine is stopped the throttle valve is brought to its idling position without the operation of the dash pot 4 so as to prevent run-on operation of the engine.

Thus a sudden deceleration of the engine causes the control valve 20 to open at once by means of the vacuum generated on the downstream side of the throttle valve 2, so that atmospheric air is introduced through the control valve 20 into the intake passage 1. This results in better combustion in the engine and the consequent maintenance of good exhaust emission quality during deceleration. Also, the closing characteristics of the throttle valve 2, as indicated at A' in Figure 2, produce a more effective braking action by the engine during deceleration, and improve driveability, as compared with closing characteristic A without the additional air supply.

WHAT WE CLAIM IS: 1. Intake control apparatus for an internal combustion engine, comprising a throttle valve mounted in an intake passage, and control means for regulating closing movement of said throttle valve under the influence of the degree of vacuum both upstream and downstream of the throttle valve, wherein there is provided air inlet means arranged to automatically admit additional air into said intake passage downstream from the throttle valve when there is a sudden increase in the degree of vacuum in the intake passage downstream from the throttle valve.

2. Apparatus as claimed in claim 1, wherein said air inlet means comprises an air inlet passage having a control valve therein, said control valve being arranged to open quickly when there is a said sudden increase in the degree of vacuum, but to close relatively slowly when said degree of vacuum is subsequently reduced.

3. Apparatus as claimed in claim 2, wherein said control valve has a movable valve element, pressure responsive means arranged to move said valve element between open and closed positions, said pressure responsive means including a movable member subjected on one side to pressure in said air inlet passage, a closed chamber on the other side of said movable member, and valve means on the movable member acting to restrict flow from the closed chamber to the air inlet passage while permitting relatively unrestricted flow in the opposite direction.

4. Apparatus as claimed in claim 3, in which said movable member is carried on an annular flexible diaphragm.

5. Apparatus as claimed in claim 3 or 4, in which said valve means comprises a flap adapted to close over an opening in the movable member, said flap having an orifice aligned with said opening.

6. Intake control apparatus for an internal combustion engine, substantially as hereinbefore described with reference to the accompanying drawings.

7. An internal combustion engine having intake control apparatus as claimed in any of

Claims

claims 1 to 6.