JPS6147979B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control system for an automobile engine, and more particularly to an ignition timing control system that advances the vacuum angle when the engine is idling.

Conventionally, in ignition timing control systems that advance the vacuum advance when the engine is idling, the vacuum advancer of the distributor is of a double diaphragm type, and negative pressure is applied to only one diaphragm during idle, thereby increasing the vacuum advance. There is a method to do this, but this method has the drawbacks of a complicated mechanism and high cost. Therefore, in order to provide the same functionality and reduce costs, a method has been considered to advance the vacuum angle by selectively introducing a high negative pressure signal and a low negative pressure signal into a single diaphragm type vacuum advancer. However, the operational response is poor, and the ignition timing does not respond immediately to the retard side, especially when the engine suddenly accelerates from a steady running state, resulting in knocking.

The present invention is intended to eliminate the drawbacks of the conventional system described above, and has improved operational responsiveness in a system that advances the vacuum angle when the engine is idling, especially when transitioning from a steady running state to sudden acceleration. An object of the present invention is to provide an ignition timing control system for an automobile engine that immediately responds to retard the ignition timing.

An embodiment of the present invention will be described below with reference to the accompanying drawings. In the drawing, the carburetor 10 is connected to the throttle valve 11 upstream of the throttle valve 11.
The throttle valve 11 is provided with an advance port 12 that generates negative pressure in response to changes in the opening of the throttle valve 11, and the downstream side of the throttle valve 11 communicates with an intake manifold 20 of the engine.

The distributor 30 includes a vacuum advancer 31 that controls the ignition timing of the engine, and the amount of vacuum advance is controlled in accordance with the negative pressure acting on the vacuum advancer 31.

The control valve device 50 connects a first body 52 having a first input port 51, a second body 55 having a second input port 53 and an output port 54, and a third body 57 having a signal port 56 using ultrasonic waves. The outer shape is formed by integrally and airtightly joining them by a suitable joining means such as welding. The diaphragm 58 has its outer circumferential portion airtightly clamped between the second body 55 and the third body 57, and its inner circumferential portion is hermetically fixed to the diaphragm piston 59. A first chamber 60 and a second chamber 61 are formed in the third body 57 and the second body 55, respectively, with the diaphragm 58 as a boundary.
Further, a third chamber 62 is formed between the first body 52 and the second body 55, and the third chamber 62 is connected to the second chamber by a control valve described later through a passage 63 formed in the second body 55. It is now possible to communicate with 61. The first chamber 60 is constantly in communication with the engine intake manifold 20 from the signal port 56 via an orifice 40 disposed in a passage 70. The second chamber 61 is connected to the passage 7 from the second input port 53.
Advance port 1 of carburetor 10 through 1
2 is in constant communication. The third chamber 62 constantly communicates with the intake manifold 20 from the first input port 51 via a passage 72 and the orifice 40, and also communicates with the vacuum advancer 31 of the distributor 30 from the output port 54 via a passage 73.
is in constant communication with

A spring 65 whose one end is locked to a retainer 64 is disposed in the first chamber 60.
The diaphragm piston 59 is constantly urged upward in the drawing by the other end. A screw 66 is disposed in a screw hole 57a provided axially in the third body 57,
The retainer 64 can be displaced in the axial direction by the screw 66, so that the urging force of the spring 65 on the diaphragm piston 59 can be adjusted within a predetermined range. A control valve 67 is disposed in the internal hollow part 59a of the diaphragm piston 59, and the valve 67 normally contacts the valve seat 55a formed in the second body 65 by a spring 68 to close the passage 63. When the differential pressure between the negative pressure in the chamber 60 and the negative pressure in the second chamber 61 reaches a predetermined value, the shoulder portion 59b of the diaphragm piston 59 lifts the valve 67 by overcoming the biasing force of the spring 65. As a result, the passage 63 opens and the second chamber 6
1 and the third chamber 62 will communicate with each other. Note that the notch 59 provided in the diaphragm piston 59
c is for improving fluid flow when the valve 67 is opened.

Next, the operation of the ignition timing control system having the above configuration will be explained. First, when the engine is idling, the negative pressure in the intake manifold 20 is passed through the passage 72 to the control valve device 5.
0 is transmitted to the first input port 51, and further transmitted to the third chamber 6.
2 to the vacuum advancer 3 of the distributor 30 through the output port 54 and the passage 73.
1. At the same time, the negative pressure in the intake manifold 20 is transferred from the signal port 56 to the first chamber 6 through the orifice 40 disposed in the passage 70.
0. Also Advanced Port 12
Atmospheric air is generated, and the atmospheric air is transmitted from the second input port 53 to the second chamber 61 via the passage 71. Therefore, when the negative pressure in the first chamber 60 reaches a predetermined value, the diaphragm piston 59 is displaced downward in the figure, the valve 67 opens the passage 63, and the atmosphere in the second chamber 61 passes through the third chamber 62 and exits the output port 54. aisle 73
It is supplied to the vacuum advancer 31 via. Therefore, during idle, the vacuum angle is advanced by a predetermined amount.

Next, during normal engine operation, the throttle valve 11 is opened and the advance port 12 is opened.
Negative pressure is generated. Since this negative pressure is approximately equal to the negative pressure of the intake manifold 20, the first chamber 60 and the second chamber 61 are approximately the same, and the spring 6
Due to the biasing force of 5, the valve 67 keeps the passage 63 closed. At this time, the negative pressure transmitted to the third chamber 62 via the passage 72 acts on the vacuum advancer 31 via the passage 73, so that the vacuum advance is performed normally.

Now, when the engine is suddenly accelerated from this normal operating state, a large amount of air flows into the intake manifold 20, and the pressure in the advance port 12 and the intake manifold 20 becomes almost equal to atmospheric pressure. At this time, the atmosphere supplied from the advance port 12 is immediately transmitted to the second chamber 61 via the passage 71, but the atmosphere supplied from the intake manifold 20 is gradually transmitted to the first chamber 60 via the orifice 40. Therefore, negative pressure remains in the first chamber 60 for a while. Therefore, the diaphragm piston 59 is displaced downward in the drawing, and the valve 67 opens the passage 63, so that the atmosphere in the second chamber 61 passes through the third chamber 62, and immediately enters the vacuum advancer from the output port 54 via the passage 73. As a result, the vacuum advance angle is cut off and the ignition timing is retarded.

As described in detail above, in the ignition timing control system of the present invention, when the engine suddenly accelerates from a steady operating state, atmospheric air is immediately transmitted to the vacuum advancer 31, and the ignition timing is retarded with good response. This has extremely excellent effects, such as being able to prevent the occurrence of knocking, and reducing costs because the mechanism is simple.

[Brief explanation of the drawing]

The drawing is a system diagram showing an embodiment of the present invention. 10: Carburetor, 11: Throttle valve,
12: Advance port, 20: Intake manifold, 30: Distributor, 31: Vacuum advancer, 40: Orifice, 50:
Control valve device, 58: diaphragm, 59: diaphragm piston, 60: first chamber, 61: second
Chamber, 63: Passage, 65: Spring, 67: Control valve, 71, 72, 73: Passage.

Claims (1)

[Claims] 1. A carburetor equipped with an advance port located upstream of the idle position of the throttle valve and generating negative pressure in response to changes in the opening of the throttle valve, and a disk equipped with a vacuum advancer that controls the ignition timing of the engine. a tributator, a first passage communicating between an engine intake manifold and the vacuum advancer, a second passage communicating between the advance port and the vacuum advancer, and a control valve device for controlling opening and closing of the second passage. a first chamber communicating with the intake manifold via orifice means; a second chamber separated from the first chamber by a diaphragm and communicating with the second passageway;
A diaphragm piston that is actuated and displaced by a differential pressure between the negative pressure of the intake manifold introduced into the chamber and the negative pressure of the advance port introduced into the second chamber, and a control valve that can be opened and closed by the actuation displacement of the diaphragm piston. and a spring that biases the diaphragm piston in a direction in which the valve closes.