JP6366005B2 - Evaporative fuel processing equipment - Google Patents

Description

  The present invention relates to an evaporated fuel processing apparatus, and more particularly to an evaporated fuel processing apparatus capable of measuring the concentration of evaporated fuel.

  Conventionally, an evaporative fuel processing apparatus that can measure the concentration of evaporative fuel is known. In the evaporative fuel processing device, a purge passage different from the fuel supply system to the engine is provided between the fuel supply tank and the engine intake pipe on the upstream side of the engine, and the evaporated fuel generated in the fuel tank at the time of refueling, Accumulate in the canister on the purge passage. Then, at a predetermined purge timing, a negative pressure is generated in the canister by operating a pump provided between the canister and the engine intake pipe on the purge passage, whereby the evaporation accumulated in the canister Fuel is supplied to the engine intake pipe.

  For example, Patent Document 1 describes that the air-fuel ratio when supplying evaporated fuel to the engine is optimized by measuring the concentration of evaporated fuel released from the canister during purging.

JP 2009-138561 A

  In general, when purging the evaporated fuel accumulated in the canister, fresh air is introduced from the outside into a substance such as butane accumulated in a liquid state in the canister and passed through the canister. When fresh air is introduced into the canister, a substance such as butane in a liquid state accumulated in the canister is vaporized and separated from the canister and supplied to the engine.

  The vaporization heat is generated when the evaporated fuel leaves the canister. The inventors have determined that the temperature characteristics of the vaporization heat, particularly the amount of decrease in temperature or the rate of decrease, and the amount of evaporated fuel discharged from the canister, It was found that there is a close relationship between the two. Therefore, based on the above knowledge, the present invention provides an evaporative fuel processing apparatus capable of calculating the evaporated gas concentration in the purge passage on the downstream side of the canister more easily and accurately than the conventionally used method. The purpose is to provide.

  In order to solve the above problems, the present invention provides a purge passage extending from a fuel tank toward an engine intake pipe, a canister for receiving evaporated fuel from the fuel tank and accumulating evaporated fuel, and air in the canister An evaporative fuel processing apparatus comprising: an atmosphere release valve for introducing gas; and a pressure pump connected to the downstream side of the canister on the purge passage, the downstream side of the canister on the purge passage A temperature sensor that detects the temperature of the gas that has passed through the canister and discharged into the purge passage downstream of the canister, and is detected by the temperature sensor during purging and passes through the canister. Based on the amount of decrease in the temperature of the gas released to the purge passage downstream of the canister, the downstream of the canister Calculating the fuel vapor concentration of the gas in the over-di passageway is characterized.

In this case, it is preferable that the vaporized fuel concentration of the gas in the purge passage is calculated to be higher as the temperature decrease amount of the gas passing through the canister and discharged into the purge passage is larger.

  In order to solve the above problems, the present invention provides a purge passage extending from a fuel tank toward an engine intake pipe, a canister for receiving evaporated fuel from the fuel tank and accumulating evaporated fuel, An evaporative fuel processing apparatus comprising an atmosphere release valve for introducing air into the purge passage and a pressurizing pump connected to the downstream side of the canister on the purge passage, wherein the canister on the purge passage A temperature sensor is provided on the downstream side to detect the temperature of the gas passing through the canister and discharged into the purge passage downstream of the canister, and passes through the canister detected by the temperature sensor during purging. The canister downstream based on the rate of decrease in the temperature of the gas discharged to the purge passage downstream of the canister Calculating the fuel vapor concentration of the gas in the purge passage, and characterized.

In this case, it is preferable that the higher the rate of decrease in the temperature of the gas that has passed through the canister and released into the purge passage, the higher the vaporized fuel concentration of the gas in the purge passage.

  According to the present invention configured as described above, the temperature of the gas in the purge passage that passes through the canister and is discharged from the canister during the purge is measured using the temperature sensor, and the amount of decrease in the measured temperature is measured. Alternatively, the vaporized fuel concentration of the gas in the purge passage on the downstream side of the canister can be calculated based on the decrease rate.

  In the present invention, it is preferable that a purge valve provided on the downstream side of the pressurizing pump is provided on the purge passage, and the opening degree of the purge valve is controlled based on the calculated evaporated fuel concentration.

  According to the present invention configured as described above, it is possible to control the amount of evaporated fuel supplied to the engine intake pipe by adjusting the opening of the purge valve based on the calculated evaporated fuel concentration.

  As described above, according to the present invention, the concentration of the evaporated fuel in the purge passage on the downstream side of the canister can be calculated more easily and accurately.

It is a block diagram which shows the evaporative fuel processing apparatus by embodiment of this invention. It is a flowchart which shows operation | movement of the evaporative fuel processing apparatus by embodiment of this invention. The example of the map which the evaporative fuel processing apparatus by embodiment of this invention uses is shown.

  Hereinafter, an evaporated fuel processing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a fuel vapor processing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the evaporated fuel processing apparatus is configured to supply evaporated fuel generated in a fuel tank 5 to an engine intake pipe 3 connected to the engine 1. The evaporative fuel processing device includes a purge passage extending from the fuel tank 5 toward the engine intake pipe 3. On the purge passage, a canister 7, a pressurizing pump 9, and a purge valve 11 are provided from the upstream side. In this specification, “upstream side” and “downstream side” are defined based on the direction in which the evaporated fuel flows in the purge passage unless otherwise specified. The fuel tank 5 side in the purge passage extending from the fuel tank 5 as a starting point is referred to as “downstream side”, and the engine intake pipe 3 side in the purge passage terminating at the engine intake pipe 3 is referred to.

  The canister 7 is connected to the fuel tank 5 and adsorbs and accumulates the evaporated fuel flowing from the fuel tank 5. The canister 7 includes a first cylindrical container 7a and a second cylindrical body 7b that accommodate an adsorbent such as activated carbon, and is arranged at one end of the first cylindrical container 7a and the second cylindrical container 7b. The part is connected so that gas can go back and forth between the first cylindrical container 7a and the second cylindrical container 7b. The other end of the first cylindrical container 7 a receives the evaporated fuel from the fuel tank 5. The evaporated fuel that has flowed from the fuel tank 5 into the canister 7 in a gaseous state is aggregated and accumulated in the adsorbent of the canister in a liquid state. The other end of the second cylindrical container 7 b is connected to a fresh air supply pipe 13 for supplying fresh air to the canister 7.

  The pressure pump 9 has an inlet connected to the canister 7 and an outlet connected to the purge valve 11. The pressure pump 9 generates a negative pressure on the upstream side of the pressure pump 9 in the purge passage under the control of the ECU 15 during the purge to supply the evaporated fuel to the engine intake pipe 3. A positive pressure is generated downstream. Thereby, the evaporated fuel adsorbed in the canister 7 is sucked and can flow toward the downstream side of the canister 7.

  The purge valve 11 is provided immediately upstream of the engine intake pipe 3 and adjusts the supply amount of the evaporated fuel that has passed through the purge passage to the engine intake pipe 3 in accordance with the opening thereof. . The opening and closing of the purge valve 11 is controlled by the ECU 15. When the purge valve 11 is open, the canister 7, the pressurizing pump 9, and the engine intake pipe 3 are connected, and when the purge valve 11 is closed, The connection between the canister 7 and the pressurizing pump 9 and the engine intake pipe 3 is cut off.

  Between the fuel tank 5 and the first cylindrical container 7a of the canister 7, there is provided an evaporated fuel supply pipe 17 for supplying the evaporated fuel generated in the fuel tank 5 into the first cylindrical container 7a. . The evaporated fuel supplied from the evaporated fuel supply pipe 17 to the first cylindrical container 7 a is adsorbed by the adsorbent in the canister 7 and accumulated in the canister 7. In addition, an accumulated fuel supply pipe 19 that supplies evaporated fuel accumulated in the canister 7 to the pressurizing pump 9 is provided between the canister 7 and the pressurizing pump 9. Further, the second cylindrical container 7 b is provided with a fresh air supply pipe 13 for supplying fresh air from the outside to the canister 7. An air release valve 21 that is controlled to be opened and closed by the ECU 15 is provided at the outside air inlet of the fresh air supply pipe 13.

  A temperature sensor 21 is provided between the canister 7 and the pressurizing pump 9 on the purge passage for detecting the temperature of the mixed gas discharged from the canister 7 and containing the evaporated fuel. The temperature detected by the temperature sensor 21 is supplied to the ECU 15.

  Next, evaporative fuel concentration measurement control and evaporative fuel supply control based on the measured concentration by the evaporative fuel processing apparatus according to the present embodiment will be described in detail.

  FIG. 2 is a flowchart showing evaporated fuel concentration measurement control and evaporated fuel supply control based on the measured concentration. When a purge condition such as a sufficiently high temperature of the engine 1 is achieved and a series of processing starts, the ECU 15 opens the purge valve 11 and the air release bubble 21 in step S1, and further pressurizes the pressure pump 9 Is activated. As a result, a negative pressure is generated downstream of the pressurizing pump 9, and fresh air flows into the canister 7 through the atmosphere release valve 21. When fresh air flows into the canister 7, an air flow from the first cylindrical container 7 a of the canister 7 toward the second cylindrical container 7 b is generated in the canister 7. When the airflow passes through the adsorbent, the liquid fuel adsorbed by the adsorbent is detached from the adsorbent and is released from the canister 7 in a gaseous state. When the fuel is separated from the adsorbent and vaporizes, the temperature of the airflow is rapidly lowered by the heat of vaporization, and thereby the temperature of the mixed gas of fuel and air released from the canister 7 is also rapidly lowered.

  According to the knowledge of the inventors, it has been found that there is a close relationship between the temperature characteristics of the gas mixture at this time and the amount of evaporated fuel in the gas mixture. That is, if the amount of evaporated fuel adsorbed on the canister 7 is large and the amount of evaporated fuel in the mixed gas released from the canister 7 when fresh air is introduced is large, the amount of decrease in the temperature of the mixed gas, and On the other hand, if the amount of evaporated fuel adsorbed on the canister 7 is small and the amount of evaporated fuel in the mixed gas is small, the amount of decrease in the temperature of the mixed gas and the decreasing rate are small.

  Therefore, in step S2, the ECU 15 monitors the temperature of the mixed gas discharged from the canister 7 with time using the temperature sensor 23 provided on the downstream side of the canister 7, and thereby the discharged mixed gas is monitored. The amount of temperature decrease and / or the rate of decrease is detected. Next, in step S3, the ECU 15 refers to a map showing the correlation between the outlet temperature of the canister and the elapsed time, which is created based on a test or the like and stored in storage means such as a ROM. The concentration of the evaporated fuel in the discharged mixed gas is calculated.

  FIG. 3 shows an example of the map. More specifically, FIG. 3 shows the temperature change of the mixed gas discharged from the canister when three kinds of canisters having different evaporated fuels are introduced with fresh air. When the amount of evaporated fuel adsorbed by the canister is 82 g, the canister outlet temperature stabilizes after gradually decreasing, as shown by the curve L1. When the amount of evaporated fuel adsorbed on the canister is 120 g, as shown by the curve L2, the outlet temperature of the canister once decreases and then stabilizes while gradually increasing. When the amount of evaporated fuel adsorbed on the canister is 136 g, the outlet temperature of the canister drops rapidly and then stabilizes while gradually rising, as shown by the curve L3. When attention is paid between the start of purge (0 seconds) and 100 seconds, it can be seen that there are significant differences in the amounts of change and slopes (change rates) of the curves L1 to L3. Therefore, a map indicating the relationship between the adsorption amount, the outlet temperature of the canister and the elapsed time obtained experimentally is stored, and the adsorption amount of the evaporated fuel by the canister is obtained by referring to the map stored at the time of purging. be able to. The vaporized fuel content in the mixed gas at the initial stage of purge of the canister substantially corresponds to the amount of vaporized fuel adsorbed by the canister. Therefore, from the canister, in the purge passage on the downstream side based on the map, It is possible to calculate the content of the evaporated fuel in the mixed gas released to the gas.

Accordingly, the ECU 15 monitors the detected value of the temperature by the temperature sensor 23 for 100 seconds from the start of purge (0 second), and the amount of change in temperature, that is, the number of drops in 100 seconds, or the rate of change in temperature, for example 0 The maximum slope value of the curve indicating the temperature change between seconds and 100 seconds is calculated. Then, with reference to a map as shown in FIG. 3 , the adsorption amount of the evaporated fuel adsorbed in the canister 7 is derived. Then, the ECU 15 calculates the concentration of the evaporated fuel in the mixed gas released from the canister 7 based on the adsorption amount of the evaporated fuel. This process is based on a map showing the correlation between the amount of evaporated fuel adsorbed in the canister and the concentration of evaporated fuel released from the canister, which is created based on tests and stored in storage means such as a ROM. Done. Thereby, the concentration of the evaporated fuel released from the canister 7 can be calculated.

  Next, in step S4, the ECU 15 adjusts the opening of the purge valve 11 based on the calculated concentration of evaporated fuel. As a result, the amount of evaporated fuel supplied from the purge passage to the engine intake pipe 3 can be controlled.

  Although the map shown in FIG. 3 is illustrative, if the adsorption amount of the evaporated fuel of the canister 7 is large, the amount of decrease or rate of decrease in the temperature of the outlet of the canister 7 tends to increase. Accordingly, particularly when the amount of evaporated fuel adsorbed by the canister 7 is large and the amount of evaporated fuel supplied from the purge passage to the engine supply pipe 3 tends to increase, the temperature characteristics of the mixed gas discharged from the canister 7 change. . If the temperature characteristic changes greatly, the change can be detected more easily. Therefore, even if the map is simplified to some extent, the amount of evaporated fuel supplied to the engine supply pipe 3 by purging The increase in the rich atmosphere in the engine 1 can be suppressed.

  As described above, according to the embodiment of the present invention, it is possible to calculate the concentration of the evaporated fuel accumulated in the canister more easily and accurately than in the prior art.

7 Canister 9 Pressure pump 11 Purge valve 21 Atmospheric release valve 23 Temperature sensor

Claims (5)

A purge passage extending from the fuel tank toward the engine intake pipe;
A canister for receiving evaporative fuel from a fuel tank and accumulating evaporative fuel;
An air release valve for introducing air into the canister;
An evaporative fuel processing apparatus comprising: a pressurizing pump connected to a downstream side of the canister on the purge passage;
A temperature sensor provided on the purge passage on the downstream side of the canister and detecting the temperature of the gas passing through the canister and discharged to the purge passage downstream of the canister;
Gas evaporative fuel in the purge passage downstream of the canister based on a decrease in temperature of the gas passing through the canister and discharged into the purge passage downstream of the canister, detected by the temperature sensor during purging An evaporative fuel processing apparatus characterized by calculating a concentration. 2. The evaporated fuel processing apparatus according to claim 1, wherein the evaporated fuel concentration of the gas in the purge passage is calculated to be higher as the amount of decrease in the temperature of the gas passing through the canister and discharged into the purge passage is larger. . A purge passage extending from the fuel tank toward the engine intake pipe;
A canister for receiving evaporative fuel from a fuel tank and accumulating evaporative fuel;
An air release valve for introducing air into the canister;
A pressurizing pump connected to the downstream side of the canister on the purge passage;
An evaporative fuel processing apparatus comprising:
A temperature sensor provided on the purge passage on the downstream side of the canister and detecting the temperature of the gas passing through the canister and discharged to the purge passage downstream of the canister;
The vaporized fuel in the purge passage downstream of the canister is detected by the temperature sensor at the time of purging based on the rate of decrease in the temperature of the gas passing through the canister and discharged into the purge passage downstream of the canister An evaporative fuel processing apparatus characterized by calculating a concentration. The evaporated fuel processing apparatus according to claim 3, wherein the higher the rate of decrease in the temperature of the gas passing through the canister and discharged into the purge passage, the higher the evaporated fuel concentration of the gas in the purge passage. .   5. The purge valve according to claim 1, further comprising a purge valve provided downstream of the pressurizing pump on the purge passage, and controlling an opening of the purge valve based on the calculated evaporated fuel concentration. The evaporative fuel processing apparatus of item 1.

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