GB2038416A

GB2038416A - Auxiliary Air Regulating Device for a Fuel Injection Internal Combustion Engine

Info

Publication number: GB2038416A
Application number: GB7944427A
Authority: GB
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1978-12-28
Filing date: 1979-12-28
Publication date: 1980-07-23
Also published as: FR2445444A1; DE2952550A1; JPS5591737A

Abstract

An air valve (11) in a bypass passage (9) around the throttle valve (4) is responsive to the operating conditions of the engine to control the amount of air passing through the bypass passage. The operation is such that the air valve (11) is more constricted when the vacuum downstream of the throttle valve (4) is greater. The opening of the air valve is also dependent upon engine temperature and speed, vehicle speed and the position of the throttle valve (4). <IMAGE>

Description

SPECIFICATION Auxiliary Air Regulating Device for a Fuel Injection Internal Combustion Engine The present invention relates to an auxiliary air regulating device for fuel injection internal combustion engines.

In a conventional internal combustion engine of this type, as an air increasing means, portions of an air intake passage upstream and downstream of a throttle valve are connected through an air regulator, which allows additional air to bypass the throttle valve during cold starting. Further, a vacuum damping mechanism, employing for example a dashpot, is provided to increase air supply during deceleration. Moreover, it is also necessary for the conventional combustion engine to be provided with an air regulating device for controlling the idling speed.

Accordingly, the arrangement of parts around the throttle valve tends to be complex, the manufacturing cost is high, and maintenance and servicing are awkward and time-consuming because many separate components are used to carry out basically the same air regulation.

It is therefore an object of the present invention to provide an auxiliary air regulating device for a fuel injection internal combustion engine which overcomes the defects encountered with conventional devices.

It is still another object of the invention to provide an auxiliary air regulating device for a fuel injection internal combustion engine which has an air valve within a passage bypassing the throttle valve in which a vacuum supplied to a vacuum chamber of a diaphragm device connected to the air valve is controlled in accordance with various engine operating conditions.

In the accompanying drawings:- Fig. 1 is a cross-sectional view of a first embodiment of an auxiliary air regulating device for a fuel injection internal combustion engine according to the present invention, Fig. 2 is a side view of the device of Fig. 1 taken along the line Il-Il partly in cross-section, Fig. 3 is a side view of the device of Fig. 1 taken along the line Ill-Ill and partly broken away to show the interior thereof, Fig. 4 is a cross-sectional view of the portion shown in Fig. 3 taken along the line IV--IV, Fig. 5 is a cross-sectional view of another embodiment of the portion shown in Fig. 4, Fig. 6 is a schematic diagram of a second embodiment of the device according to the present invention, Fig. 7 is a schematic diagram of a third embodiment of the device according tothe present invention, Fig. 8 is a cross-sectional side view of a fourth embodiment of the device according to the present invention, Fig. 9 is a cross-sectional view of a portion of the device shown in Fig. 8 taken along the line IX-IX, Fig. 10 is a schematic diagram of a fifth embodiment of the device according to the present invention, and Fig. 11 is a block diagram of a control device used in the present invention.

Referring to Fig. 1, an air intake passage 1 for an engine is shown in which is provided a throttle chamber 2, a throttle valve 4 fixed to a throttle valve shaft 3, a fuel reflecting plate 5 situated downstream of the throttle valve 4, a fuel 'injection valve 6 of the electromagnetic type facing the plate 5, a pressure regulator 7 of the diaphragm type which adjusts the fuel pressure to be supplied to the injection valve 6, and a bypass air passage 8 extending to the nozzle portion 6' of the injection valve 6.

The device also comprises a bypass passage 9 for aliowing a bypass flow of intake air around the valve 4, an air valve seat 10 and a rotatable air valve 11 which is slidable over the seat 10 and which increases or decreases the path area thereof. The air valve 11 is fixed by a screw 13 provided in a bush 12 positioned in the throttle chamber 2.

An air valve shaft 14 fixed to the center of rotation of the valve 11 projects outside an air valve cover 1 5 so that it can be used to operate the valve.

The gap between the air valve shaft 14 and the air valve cover 1 5 is sealed by a sealing means 16.

Fig. 2 shows a cross-sectional view of the device of Fig. 1 taken along the line Il-Il. A lever 1 8 is fixed by a lever holder 1 7 to the outer end of the air valve shaft 14. The end of the lever 18 is pivotally coupled by a link 21 to the end of a rod 20 of a diaphragm device 1 9 fixed to the periphery of the throttle chamber 2. The arrangement of the valve 11 over the valve seat 10 is best seen in Fig. 3.

In operation, the intake vacuum downstream of the throttle valve 4 is appled through a vacuum path 24 to a vacuum chamber 23 defined in part by a diaphragm 22 in the diaphragm device 19.

When the vacuum in the chamber 23 reaches maximum, the diaphragm 22 moves to the right against the force of a spring 25, and the rod 20 and the link 21 are moved to the right, thus rotating the air valve shaft 14 counterclockwise through the lever 1 8. As a result, the air valve 11 is also rotated in the counter-clockwise direction against the force of a spring 26 and the smallest portion of the air hole 11' formed in the air valve 11 coincides with the air hole 10' which is formed in the air valve seat 10.

On the other hand, when the vacuum in the vacuum chamber 23 is at a minimum, the diaphragm 22 is returned to its original position by the returning force of the spring 26 so that the air valve 11 is held in the position shown in Fig. 3 so as to open fully the- bypass passage 9 with the largest portion of the air hole 11' aligned with the air hole 10'. In addition, in the vacuum path 24, as shown in Fig. 4, there is provided a one-way check valve 27 for preventing the flow of air from the vacuum chamber 23 to the vacuum outlet of the intake passage 1 and a passage bypassing the one-way valve 27 and including a throttling element which is shown as a small orifice 28 in Fig. 4, but may equally be a porous element of sintered metal 29 as shown in Fig. 5.This allows the vacuum path 24 to transmit a vacuum in either direction, but means that a delay is introduced if the vacuum in the intake passage 1 increases suddenly. Accordingly, during acceleration, the vacuum in the intake passage 1 is decreasing, so that the vacuum is promptly transmitted through the one-way check valve 27 to the vacuum chamber 23, as a control vacuum.

As a result, the vacuum in the chamber 23 diminishes, and the air valve 11 is returned by the spring 26 to the position shown in Fig. 3, with the largest portion of the air hole 11' superimposed on the air hole 10' of the air valve seat 10; thus the bypass passage 9 is fully opened.

On the other hand, during deceleration, the intake vacuum downstream of the valve 14 increases. In this case, however, the one-way valve 27 closes so that the control vacuum is delayed by the throttling element, and the pressure in the chamber 23 increases only gradually. As a result, the passage area of the air valve 11 is gradually decreased by the rotation of the valve 11 in the counterclockwise direction as shown in Fig. 3, so that the air bypassing the throttle valve 4 decreases gradually.

Consequently, no degradation of burning is caused by the rapid increase in inlet vacuum when the engine is decelerating, and the possibility of misfiring is also removed.

When the bypass air is controlled as described above, the conventional use of a dashpot or similar damping means is eliminated, and the throttle valve 4 is always returned promply.

Furthermore, it is easy to make the diaphragm 22 compact, and problems with adjustment of springs and friction elements are largely eliminated. It has been found that this embodiment improves the standards of reduction of HC and CO in the exhaust gas; this serendipitous result of the present invention is by no means, however, restricted to this particular embodiment.

Fig. 6 is a schematic diagram of a second embodiment of the present invention, in which an atmospheric passage 24a is connected to an intermediate point of the passage 24 from the diaphragm device 19 to the one-way valve 27.

The atmospheric passage 24a is selectively opened to atmospheric pressure through a pressure adjusting valve 30. The opening 30' of the valve 30 is controlled by the difference between inlet vacuum and atmospheric pressure, to introduce a suitable dilution into the control vacuum in the passage 24. This allows the amounts of HC and CO in the exhaust gas to be reduced during deceleration, as by using a conventional damping device.

Fig. 7 shows a third embodiment of the auxiliary air regulating device according to the present invention in which the inlet vacuum is introduced into the vacuum passage 24 through a vacuum stabilizing means 31. In this case, a fine adjustment of the inlet vacuum for coping with fluctuations in the vacuum source is not required for the orifice as the maximum inlet vacuum is held constant. In order to control the air amount both when starting the engine from cold, and during warm running, in addition to the air adjusting function during deceleration as described above, a fourth embodiment of the auxiliary air regulating device according to the present invention is used.

This fourth embodiment is shown in Figs. 8 and 9. A needle seat 33 is provided in the vacuum passage which branches from the path 24. In this case, a needle valve 35 which is driven by a bimetallic strip 34 is provided opposite the needle seat 33 so as to control the degree of atmospheric dilution of the control vacuum in accordance with the temperature of the engine.

Moreover, a vacuum pressure passage 32 is open to the atmosphere through an air release passage 37 and a chamber 36 containing the needle seat 33 and bimetallic strip 34.

In other words, when starting the engine from cold the intake suction is small and it is necessary for the area of the bypass passage 9 to be large.

Accordingly, when the temperature of the engine is below a predetermined value the needle valve 35 is opened by the bimetallic strip 34, and the amount of atmospheric dilution of the control vacuum is increased, thus increasing the bypass air flow. On the other hand, when the vacuum increases immediately after explosion, the area of the bypass passage 9 is decreased in the same way as when decelerating, whereby, also in this case, degradation of burning and misfiring are largely prevented.

Fig. 1 0 shows a fifth embodiment of the present invention in which a valve member 39' of an electromagnetic valve 39 cooperates with the open end ofa vacuum passage 38 which branches from the vacuum passage 24, and the electromagnetic valve 39 is controlled by a control circuit 41 connected to a sensor 40 for detecting the speed of the engine. In this case, the same diaphragm device 1 9 and air valve 10 with respect to the idling speed can be used for varying the air amount according to the engine speed as well as the control to respond to deceleration and temperature. The electromagnetic valve 39 controls the ratio of time of the opening and closing states at the opening end of the vacuum passage 38, thereby regulating the amount of atmospheric dilution of the intake vacuum being taken into the vacuum passage 24.

Fig. 1-1 shows a block diagram of a sixth embodiment of the invention in whidh the air amount is adjusted by one electromagnetic valve and one diaphragm device to respond correctly to the deceleration, temperature and speed during idling of the engine. The device in Fig. 11 comprises a temperature detector 101, a throttle valve opening detector 102, a vehicle speed detector 103 and an engine speed detector 104 and a decision circuit 105 having a temperature calculator 106, a throttle valve opening calculator 107, an idling detector 108, and engine speed calculator 109.

In operation, the temperature of the engine is detected by the temperature detector 101. If the temperature of the cooling water is detected, for example, a cold start control signal is supplied to a control circuit 110 if the temperature is below, say, 550C at which the engine runs smoothly. In the control circuit 110, a solenoid valve (not shown) is controlled by a pulse width control and the proportion of the atmospheric dilution of the intake suction is increased as the temperature of the engine decreases. For the purpose of effecting the same control, a linear solenoid may be used.

Further, if it is constituted so that a temperature sensor produces an output or a bimetallic arrangement becomes operative by means of a heater combined therewith when a predetermined time necessary for warming up of the engine passes, thereby enabling to effect the same control.

The opening of the throttle valve is determined and when it is nearly fully closed or fully opened, it is determined from the vehicle speed whether the vehicle is idling or decelerating. Of course, the speed'of the engine can be used instead of the vehicle speed for the determination. When deceleration is detected, deceleration control is carried out in accordance with the speed of the engine. Namely, if decelerating when the speed of the engine is high, the control vacuum applied to the vacuum chamber of the diaphragm device 19 is decreased, so that the atmospheric dilution is high, while the bypass passage opening is made relatively large to supply the necessary amount of air required for deceleration.

When the idling condition is detected, the speed is sensed and the bypass air amount is controlled so as to retain the desired speed. In addition, such control is normally carried out as an additional function of a microcomputer already installed for use in an EGI system.

As described above, the structure according to the present invention is simple, and provides for stable and smooth operation of the diaphragm device operating the auxiliary air bypass valve.

Since the control vacuum operating the diaphragm device can be diluted with atmospheric air under the control of mechanical means or microcomputer means, for example, responding to operating conditions, it is easy to make further required adjustments to the auxiliary air intake amount. Thus costs and construction and maintenance efforts are reduced, and the system is made more reliable.

Claims

1. In a fuel injection internal combustion engine including a throttle valve within an air intake passage, an auxiliary air regulating device comprising: a bypass passage joining a point in the air intake passage upstream of the throttle valve to a point in the air intake passage downstream of the throttle valve; an air valve within the bypass passage which controls the amount of air flowing through the bypass passage; and means for operating the air valve in accordance with the operating conditions of the engine.

2. An auxiliary air regulating device as claimed in claim 1 in which the air valve comprises a sliding valve member.

3. An auxiliary air regulating device as claimed in claim 1 in which the means for operating the air valve comprises a vacuum operated diaphragm device.

4. An auxiliary air regulating device as claimed in claim 1 further comprising a vacuum passage connecting a point in the intake passage downstream of the throttle valve to the diaphragm device, and within the vacuum passage a delay device which comprises a one way valve which allows air to pass when the pressure on the side further from the diaphragm device is higher than the pressure on the side nearer the diaphragm device, and arranged in parallel with the one way valve a passage including a throttling element.

5. An auxiliary air regulating device as claimed in claim 4, in which the throttling element comprises a small orifice.

6. An auxiliary air regulating device as claimed in claim 4, in which the throttling element comprises a plug of sintered metal.

7. An auxiliary air regulating device as claimed in claims 4 further comprising an atmosphere passage connecting a point in the vacuum passage to an atmosphere control means which regulates the amount of atmospheric dilution of the control vacuum.

8. An auxiliary air regulating device as claimed in claim 7, further comprising a means for controlling the atmosphere control means in accordance with the operating conditions of the engine.

9. An auxiliary air regulating device as claimed in claims 1, in which the means for operating the air valve includes a microcomputer.

10. An auxiliary air regulating device substantially as described with reference to, and as illustrated in, Figs. 1 to 4, or Fig. 5, or Fig. 6, or Fig. 7, or Figs. 8 and 9, or Fig. 10 of the accompanying drawings.