Gas separation: apparatus – Solid sorbent apparatus – With control means responsive to sensed condition
Reexamination Certificate
2002-04-12
2004-02-24
Lawrence, Frank M. (Department: 1724)
Gas separation: apparatus
Solid sorbent apparatus
With control means responsive to sensed condition
C096S112000, C096S114000, C096S116000, C096S146000, C123S519000
Reexamination Certificate
active
06695895
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosures of Japanese Patent Applications Nos. 2001-135026 filed on May 2, 2001 and 2001-226436 filed on Jul. 26, 2001, including their specifications, drawings and abstracts, are incorporated herein by reference in their entireties.
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a fuel vapor handling apparatus of an internal combustion engine, and to a diagnostic apparatus of the fuel vapor handling apparatus.
2. Description of Related Art
Internal combustion engines that use a high-volatile fuel, such as gasoline or the like, are equipped with a fuel vapor handling apparatus for preventing fuel vapor formed in a fuel tank from being released into the atmosphere. Fuel vapor handling apparatus equipped with a canister are widely known. A canister is formed by a container and a fuel adsorption-capable adsorbent contained in the container. Fuel vapor introduced from the fuel tank via a fuel vapor introducing port is temporarily adsorbed to the adsorbent. If negative pressure is caused in an intake pipe due to operation of the internal combustion engine, atmospheric air is supplied into the canister via an atmospheric port due to the negative pressure, so that fuel desorbs from the adsorbent, and is purged into the intake pipe via a purge port. The purged fuel is drawn into engine cylinders together with intake air, thus forming a portion of the air-fuel mixture.
In direct injection type internal combustion engines that conduct stratified charge combustion, or internal combustion engines installed in hybrid vehicles that use an electric motor and an internal combustion engine as drive power sources, the degree of opening of a throttle valve is set to a value relatively shifted to a fully-open side, and therefore there may be a case where the negative pressure used to purge the fuel vapor adsorbed to the canister lacks. Hence, the fuel vapor purge capability is reduced. A technology is proposed (for example, in Japanese Patent Application Laid-Open No. 5-340315) which makes up for insufficient negative pressure in the intake pipe by providing a purge pump on an atmospheric port side or on a purge port side, and increasing the pressure at the side of the atmospheric port of the canister or increasing the negative pressure at the side of the purge port so as to accelerate the supply of air into the canister.
Another technology that adjusts the amount of purge by changing the strength of rotation of a purge pump is proposed in Japanese Patent Application Laid-Open No. 11-30185.
However, the aforementioned technologies described in Japanese Patent Application Laid-Open Nos. 5-340315 and 11-30185 are not necessarily practical if accessory loss and the life spans of the purge pump and its power output section are taken into consideration.
SUMMARY OF THE INVENTION
It is one object of the invention to provide a practical fuel vapor handling apparatus having a purge pump.
In accordance with a first aspect of the invention, a fuel vapor handling apparatus includes a fuel vapor introducing port connected to a fuel tank, a purge port connected to an intake pipe of an internal combustion engine, and a canister which is formed by a container containing an adsorbent that adsorbs a fuel vapor from the fuel tank, and which has an atmospheric port that is open to an atmospheric pressure. The apparatus supplies air into the canister via the atmospheric port by using a purge pump, and purges a fuel desorbed from the adsorbent into the intake pipe via the purge port. The fuel vapor handling apparatus further includes a controller that controls the purge pump. The controller is set so that the purge pump intermittently operates.
Due to the intermittent operation, the canister internal temperature, which is reduced by the latent heat of vaporization at the time of desorption of fuel during an operating period, rises due to heat transferred from a canister-installed atmosphere and the like during a non-operating period between operating periods. Thus, desorption of fuel is facilitated. Therefore, fuel can be purged efficiently. Furthermore, corresponding to the amount of non-operating periods, the actual operating time of the purge pump is reduced, and the life of the purge pump increases. Practicality thus improves.
In the first aspect described above, the fuel vapor handling apparatus may further include a heater that heats an interior of the canister.
Therefore, during a non-operating period, the canister internal temperature can be sufficiently recovered from a temperature level to which it was reduced during the operating period. Hence, the purging can be more efficiently performed. Corresponding to an enhanced recovery from a reduced canister internal temperature, the load on the purge pump is reduced. Therefore, a low-output purge pump will suffice, and the life of the purge pump can be further increased.
In the first aspect, the controller may control a purge valve that changes between a connection between the canister and the intake pipe and a disconnection between the canister and the intake pipe, as well as the purge pump. In addition, the controller may be set so that the purge pump and the purge valve intermittently operate, and so that a timing at which the purge valve opens is delayed a predetermined time from a timing at which the purge pump turns on.
Since the timing at which the purge valve opens is delayed from the timing at which the purge pump turns on, a period during which the amount of flow of air becomes unstable due to a delay in starting the purge pump is excluded from the actual purge period. Therefore, the linearity of the amount of purge flow relative to the length of the open period of the purge valve improves. Hence, the amount of purge can be precisely controlled.
In the first aspect, the controller may control a purge valve that changes between a connection between the canister and the intake pipe and a disconnection between the canister and the intake pipe, as well as the purge pump. In addition, the controller may be set so that the purge pump and the purge valve intermittently operate, and so that a timing at which the purge valve closes and a timing at which the purge pump turns off are substantially synchronous.
Since the purge valve closes substantially simultaneously with the turning off of the purge pump, a period following the turning off of the purge pump during which the amount of flow of air ejected gradually decreases and does not become constant is excluded from the actual purge period. Therefore, the linearity of the amount of purge flow relative to the length of the open period of the purge valve improves. Hence, the amount of purge can be precisely controlled.
In the above-described aspect, the controller may be set so that a timing at which the purge valve closes and a timing at which the purge pump turns off are substantially synchronous.
In addition to the exclusion of the period during which the amount of flow of air becomes unstable due to a delay in starting the purge pump from the actual purge period, the purge valve closes substantially simultaneously with the turning off of the purge pump, so that the period following the turning off of the purge pump during which the amount of flow of air ejected gradually decreases and does not become constant is also excluded from the actual purge period. Therefore, the linearity of the amount of purge flow relative to the length of the open period of the purge valve improves. Hence, the amount of purge can be precisely controlled.
In the first aspect, the controller is set so as to determine a number of on/off repetitions of the purge pump so that a cumulative amount of actual operating durations during an intermittent operation increases as an instructed purge amount increases.
If the cumulative amount of actual operating durations is prescribed in accordance with the instructed purge amount so as to use the purge pump in a restricted manner, the life of the purge pump can be increased. If a heater is provided, the cumulative amount of actual ope
Hyodo Yoshihiko
Itakura Hideaki
Kato Naoya
Kawano Takanobu
Takeyama Masaki
Lawrence Frank M.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
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