Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2001-12-20
2004-01-20
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090170, C123S348000
Reexamination Certificate
active
06679205
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates a control system of an engine and also relates to a control method of the engine.
2. Description of the Related Art
An engine generally has an intake device, which is provided with a solenoid valve to control an amount of intake air on the basis of a ‘DUTY CONTROL’ (herein, merely called “duty control”), in order to make idling of the engine stable and improve starting performance.
It is necessary to perform an initial setting of an amount of intake air periodically to increase the above-mentioned performance to at least a certain level. Such an initial setting (initializing) operation generally requires a duty tester and the other exclusive tools.
However, all the dealers and maintenance facilities do not necessarily always have the duty tester and the other exclusive tools. In addition, any user will also not have them individually. As a result, there is a restriction in the initial setting operation and too much expenses are required. Moreover, the initializing operation is also required when shipping the engine from a manufacturing plant, and the use of the duty tester and the other exclusive tools will deteriorate the workability.
In view of such circumstances, there may be adopted measures to make an indirect duty adjustment, without using any exclusive tools, by for example closing an intake port of the solenoid valve with a finger and turning, in such a state, an air bypass screw to adjust a bypass flow rate so as to adjust the revolution number to a level, which is lower than the target revolution number. In such a case, a careful adjusting operation is required, it is not easy to carry out such an adjusting operation and the adjusting operation does not necessarily provide good results.
Further, when the amount of air is adjusted to a side relying on the solenoid, i.e., a side of a high-solenoid duty, there occurs an inconvenience such as of deteriorated starting performance, stall at a time of conducting a sudden completely closing operation, increase in power consumption, and so on.
On the other hand, when the amount of air is adjusted to an opposite side to the side relying on the solenoid, i.e., a side of a low-solenoid duty, an excessive amount of air may deteriorate reduction in revolution number of the engine during deceleration, causing difficulty in a shifting operation or increase the revolution number in an idling state, deteriorating the rate of fuel consumption. With respect to an engine of an outboard motor, for example, the engine operates in the idling state to carry out a trolling. Increase in the revolution number in the idling state makes the speed of a boat faster, thus deteriorating maneuvering properties of the boat.
In either case mentioned above, an inappropriate adjustment will not provide a full performance of the engine.
Furthermore, as mentioned hereinbefore, the intake device of the engine is provided with a solenoid valve to control an amount of intake air on the basis of a duty control so as to make idling of the engine stable and improve starting performance.
Such solenoid valve is controlled so that the revolution number of the engine becomes an aimed revolution number except for a case of full-close state of a throttle valve or starting and dashpot mode.
On the other hand, in the case of not full-close state of the throttle valve, the duty is regulated on a predetermined map so as not to be delayed through a dashpot control at a time of rapid full-close operation.
Furthermore, the solenoid valve of the engine is also controlled, even in the full-close state, in a range not causing a problem in the stating characteristic, rotation-down, engine stall or like at the dashpot control time.
However, the adjustment or control mentioned above is not always performed and, in practical, is carried out only at a time of inspection of the engine or occurrence of an inconvenient matter. Accordingly, there causes a difference between the preliminarily adjusted air amount and an air amount actually required for the engine in accordance with aged deterioration, degradation of lubrication oil, friction change or like.
For example, in a case where a sensor utilized for the control is a full-close switch performing “ON” operation at a full-close time of a throttle valve disposed inside a throttle body, a revolution number feed-back function is caused at the full-close time and no problem is, hence, caused. However, in “OFF” state of the full-close switch, i.e., in a case where the full-close switch is even little opened, the duty is controlled on the preliminarily determined map, so that there may cause a case that the revolution number of the engine is increased or decreased at the ON-OFF switching point of the full-close switch.
For example, in a case where the duty at the time of feed-back in the “ON” state of the full-close switch is set to be higher than a duty in the “OFF” state thereof, the air amount is reduced at the switching point (ON OFF) and the engine revolution number is suddenly lowered.
Furthermore, in a case where the throttle valve is returned slowly, there is a possibility of causing a case that an air amount is reduced just before the “ON” state of the full-close switch and the engine stall is caused.
On the other hand, in a case where the duty at the time of feed-back in the “ON” state of the full-close switch is set to be lower than a duty in the “OFF” state thereof, the air amount is increased at the switching point (ON OFF) and there may cause an inconvenience such that the engine revolution number is suddenly increased.
Even in a case where a throttle sensor for detecting a degree of throttle valve opening is utilized in place of the full-close switch operating at the open/close time of the throttle valve for the dashpot control or like, an inconvenient state substantially identical to that mentioned above will be caused at the switching point thereof because the throttle sensor is provided with an idle zone.
SUMMARY OF THE INVENTION
A primary object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide control system and method of an engine, which permits to initialize easily an amount of intake air without using any exclusive tools in a reliable manner.
Another object of the present invention is to provide, in addition to the above, control system and method of an engine capable of preventing a change of revolution number of the engine at a switching (open/close) point of a throttle valve of the engine.
These and other objects can be achieved according to the present invention by providing, in one aspect, a control system of an engine, in which an intake device is provided with a solenoid valve and an amount of intake air is controlled on a basis of a duty control by an element of a control unit, wherein the control unit includes means for recognizing a state which is evidently different from a normal state to thereby stationarily hold a duty of the solenoid valve at a necessary set value.
According to this aspect, it is possible to easily initialize an amount of intake air with the use of a simple tool without considering the target amount of intake air and to prevent an engine stall from occurring during the adjustment operation.
In preferred embodiments of this aspect, the evidently different state from the normal state is caused by carrying out an operation for increasing a revolution number of the engine in a fully closed state of a throttle valve. A time elapsed is set for increase in the revolution number of the engine.
The evidently different state from the normal state is caused by carrying out an operation for setting a voltage level of a terminal in a harness to a level, which is different from a normal voltage level.
The evidently different state from the normal state is caused by carrying out a switching operation of a specific switch.
The duty is set to be held stationarily after the recognition of a warming up state of the engine. The duty may be
Chang Ching
Denion Thomas
Suzuki Kabushiki Kaisha
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