Internal-combustion engines – Accessories – Covers – trays – vibrators – corrosion inhibitors – air filters
Reexamination Certificate
1999-05-20
2001-02-13
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Accessories
Covers, trays, vibrators, corrosion inhibitors, air filters
C123S456000, C123S468000
Reexamination Certificate
active
06186112
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 10-150287 filed on May 29, 1998 and Japanese Patent Application No. HEI 10-373902 filed on Dec. 28, 1998, including the specification, drawings and abstract, are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel supply apparatus for an internal combustion engine having a high pressure fuel pipe for supplying fuel, which has been pressurized by a high pressure fuel pump, to an injector of the internal combustion engine, and a seal member arranged in a fuel transfer portion of the high pressure fuel pipe for securing a sealing property.
2. Description of the Related Art
A cylinder fuel injection type internal combustion engine is structured to pressurize a fuel in a fuel tank to a high pressure by a supply pump, supply the pressurized fuel to a high pressure fuel pipe formed of a delivery pipe and the like, and directly inject and supply the fuel into a cylinder from the injector connected to the delivery pipe.
Further, fuel pressure within the high pressure fuel pipe, that is, an injection pressure of the fuel injected from the injector is controlled to a pressure suitable for an operating state of the internal combustion engine. For example, the injection pressure is controlled by controlling a discharge amount of the supply pump. In this case, the fuel pressure in the high pressure fuel pipe is normally set to be higher than that of an inlet port of fuel injection type internal combustion engine. This is because the fuel has to be injected against an internal pressure of the highly pressurized cylinder in case of the cylinder fuel injection type internal combustion engine. Further, the fuel spray is required to be atomized to secure a good combustion state.
In the fuel supply apparatus employed in the cylinder fuel injection type internal combustion engine, a seal member like O-ring has been conventionally place at a location where fuel leakage is likely to occur. For example, the O-ring has been placed at a connection portion between the delivery pipe and the injector, a connection portion between the supply pump and the delivery pipe or the like such that sufficient sealing property is obtained. The aforementioned technique is disclosed in Japanese Patent Application Laid-Open No. HEI 9-126087 or Japanese Patent Application Laid-Open No. HEI 10-73060. The technique for securing the sealing property for the connection portion using the seal member is not a complicated operation. Additionally, the O-ring is effective at damping vibrations transmitted to the high pressure fuel pipe from the supply pump.
However, the aforementioned seal member is likely to loose its flexibility and lose sealing ability when exposed to a low temperature. Accordingly, in the fuel supply apparatus using a seal member there has been a risk of leakage of a very small amount of fuel from the connection portion of the high pressure fuel pipe where the seal member is attached. For example, a leak may occur when cold starting the internal combustion engine.
SUMMARY OF THE INVENTION
The present invention provides a fuel supply apparatus for an internal combustion engine which can prevent leakage of a fuel from a high pressure fuel pipe at a low temperature. In accordance with the present invention, there is provided a fuel supply apparatus for an internal combustion engine including a high pressure fuel pipe for supplying a fuel, which has been pressurized by a high pressure fuel pump, to an injector of an internal combustion engine, a seal member for sealing a fuel transfer portion of the high pressure fuel pipe, and fuel pressure controller that estimates a sealing capacity of the seal member and that controls a fuel pressure within the high pressure fuel pipe on the basis of the estimated sealing capacity so that a predetermined sealing property can be maintained at the fuel transfer portion.
In accordance with the structure mentioned above, in the case where the sealing capacity of the seal member is reduced at a low temperature, the fuel pressure within the high pressure fuel pipe is restricted to a level at which the fuel leakage is not generated in accordance with the reduction of the sealing capacity.
Further, in general, the seal member formed by a polymeric material is likely to lose flexibility as the temperature decreases which results in deteriorated sealing capacity.
Accordingly, the fuel pressure controller estimates the sealing capacity of the seal member on the basis of an estimation of the temperature of the seal member. Therefore, it is possible to easily estimate the sealing capacity of the seal member.
Further, the fuel pressure controller reduces the fuel pressure within the high pressure fuel pipe if the estimated temperature of the seal member does not reach a temperature that is capable of securing the sealing capacity of the seal member. Accordingly, it is possible to easily estimate the sealing capacity of the seal member on the basis of the seal member temperature. When the temperature of the seal member is too low to secure the sealing capacity, it is possible to restrict the fuel pressure within the high pressure fuel pipe to a level at which the fuel leakage is not generated.
Still further, when reducing the fuel pressure within the high pressure fuel pipe as mentioned above, the fuel pressure controller may change a rate for reducing the amount of the fuel within the high pressure fuel pipe on the basis of the estimated temperature of the seal member. In accordance with the structure mentioned above, it is possible to set the fuel pressure within the high pressure fuel pipe in accordance with the seal capacity reduction.
Furthermore, since it is generally difficult to directly detect the temperature of the seal member, the fuel pressure controller comprises a detector that detects a state of the internal combustion engine that has a mutual relation to the temperature of the seal member. The fuel pressure controller also compares the detected state with a predetermined value that corresponds to a temperature that is capable of securing a sealing capacity. Thus, the fuel pressure controller reduces the fuel pressure within the high pressure fuel pipe when the comparison indicates that the detected state meets the predetermined judgment. Accordingly, it can be easily determined if the temperature of the seal member does not reach the temperature at which the seal capacity of the seal member is secured, and then the fuel pressure control can be easily realized on the basis of the temperature of the seal member.
Further, as a particular structure for detecting the state of the internal combustion engine mentioned above, the detector detects the temperature of the fuel within the high pressure fuel pipe as the state and the fuel pressure controller determines whether the detected temperature of the fuel is lower than a predetermined temperature corresponding. Alternatively, the detector detects a temperature the cooling water or the lubricating oil of the internal combustion engine and the fuel pressure controller determines when the detected temperature is lower than a predetermined temperature.
Particularly, in the former case, the fuel within the high pressure fuel pipe is directly brought into contact with the seal member and the fuel temperature has a high mutual relation with respect to the seal member temperature. Therefore, the determination of whether the seal member temperature is low is reliable.
Further, the detector can detect an elapsed time from engine start as the state and the fuel pressure controller determines whether the detected elapsed time is shorter than a predetermined time. Alternatively, the detector detects an additional amount of fuel injected from the injector after engine start or an additional amount of an inlet air supplied to the internal combustion engine after engine start and the fuel pressure controller determines when the detected added amount is less than a predete
Shibata Ryuji
Sugiyama Masanori
Takahashi Jun
Yamazaki Daichi
Yano Masaaki
Miller Carl S.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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