JP2014101830A - Evaporation fuel treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an evaporation fuel treatment capacity as much as possible in an evaporation fuel treatment device including a canister 1.SOLUTION: Each of paths 18a, 18b in which airflow passes from a drain port 7a (7b) to a purge port 6a (6b) through an adsorbent in supplying evaporation fuel to an internal combustion engine intake system, is disposed between the purge port 6a (6b) and the drain port 7a (7b) corresponding to each other in a canister 1, and path control means (first switch valve 21 and engine controller 51) for controlling the path of airflow so that the airflow passes along one path of the plurality of paths 18a, 18b in supplying the evaporation fuel to the intake system, changes the path of the airflow when a decrease amount of a temperature of the adsorbent on the path in which the airflow passes, becomes a prescribed value or more.

Description

  The present invention belongs to a technical field related to a fuel vapor processing apparatus including a canister.

  In general, an evaporative fuel processing apparatus includes a canister that contains an adsorbent such as activated carbon (see, for example, Patent Document 1). The canister has a tank port connected to the fuel tank, a purge port connected to the intake system of the engine, and a drain port that opens the inside of the canister to the atmosphere. Then, the evaporated fuel generated by evaporation in the fuel tank flows into the canister from the tank port, and the injected evaporated fuel is adsorbed by the adsorbent. The evaporated fuel adsorbed by the adsorbent is supplied to the engine intake system according to the engine operating state. That is, the canister and the engine intake system (intake pipe) are connected by a purge pipe, and the purge pipe is provided with a purge valve that is opened and closed according to the engine operating state. When the purge valve is opened, the purge pipe Then, the inside of the canister becomes negative pressure, so that outside air (air) is introduced into the canister from the drain port, and an air flow flowing from the drain port to the purge port is generated in the canister. The evaporated fuel is desorbed from the adsorbent by the air flow, and the desorbed evaporated fuel is supplied to the engine intake system via the purge pipe in a state of being mixed with air.

  In Patent Document 1, there is a case where a high concentration of evaporated fuel is adsorbed to the adsorbent in the vicinity of the purge port of the canister, and this high concentration of evaporated fuel is supplied to the engine intake system to deteriorate the emission characteristics. A main canister that adsorbs the evaporated fuel generated in the fuel tank, and a sub-canister that is connected in series with the main canister and has a purge port that communicates with the engine intake system. However, it is disclosed that a plurality of adsorption chambers having different breakthrough times are provided in parallel.

JP 2008-69703 A

  By the way, when the evaporated fuel is supplied to the engine intake system, the evaporated fuel adsorbed on the adsorbent in a liquid state is vaporized and desorbed from the adsorbent. At this time, the adsorbent is deprived of vaporization heat by the evaporated fuel, and thus the temperature is lowered. In particular, in the adsorbent near the purge port, immediately after the evaporated fuel is desorbed, the evaporated fuel flowing from the drain port side is adsorbed, and the adsorbed evaporated fuel is desorbed. Since desorption is frequently repeated, the temperature is greatly reduced. If the amount of temperature decrease is too large, the evaporated fuel adsorbed by the adsorbent becomes difficult to vaporize (are difficult to desorb), and the amount of evaporated fuel supplied to the engine intake system decreases. As a result, the amount of evaporated fuel adsorbed by the adsorbent in the canister increases, and the evaporated fuel in the canister may be discharged from the drain port to the atmosphere. Further, as disclosed in Patent Document 1, there is a high possibility that high-concentration evaporated fuel is adsorbed by the adsorbent near the purge port. From the viewpoint of preventing these, it is required to increase the processing capacity of evaporated fuel (capability of supplying evaporated fuel to the engine intake system).

  In particular, in recent years, there is a tendency to reduce the pumping loss of the engine as much as possible by using an exhaust gas recirculation device (EGR) and a variable timing mechanism (VVT) of the intake valve. It tends to be small, and coupled with the temperature decrease, the evaporated fuel adsorbed by the adsorbent becomes more difficult to desorb from the adsorbent.

  This invention is made | formed in view of such a point, The place made into the objective is to try to improve the processing capacity of evaporative fuel in an evaporative fuel processing apparatus as much as possible.

  In order to achieve the above object, according to the present invention, the evaporated fuel generated in the fuel tank is adsorbed by the adsorbent accommodated in the fuel tank, and the adsorbed evaporated fuel is desorbed from the adsorbent so as to generate the internal combustion engine. For an evaporative fuel processing apparatus having a canister for supplying to an intake system of an engine, the canister is provided corresponding to each of a plurality of purge ports connected to the intake system and the plurality of purge ports. A plurality of drain ports for opening the inside of the canister to the atmosphere, and between the corresponding purge ports and drain ports in the canister, when the evaporated fuel is supplied to the intake system, from the drain port to the purge port Each of which has an air flow path through the adsorbent, and when the evaporated fuel is supplied to the intake system, Path control means for controlling the air flow path so that the air flow flows along one of the paths, and the air flow flows when the evaporated fuel is supplied to the intake system. Determination means for determining whether or not the amount of decrease in the temperature of the adsorbent on the route that is present exceeds a predetermined value, and the route control means is provided on the route on which the air flow is flowing by the determination means. When it is determined that the amount of decrease in the temperature of the adsorbent is equal to or greater than the predetermined value, the air flow is adjusted so that the air flow flows along a path different from the path through which the air flow flows. The configuration is such that the route is changed.

  With the above configuration, the amount of decrease in the temperature of the adsorbent on the path through which the air flow is flowing (particularly the temperature of the adsorbent in the vicinity of the purge port of the path) is determined by the determination unit when the evaporated fuel is supplied to the intake system. It is determined whether or not a predetermined value has been reached. That is, it is determined whether or not there is a decrease in adsorbent temperature that makes it difficult for vaporized fuel adsorbed by the adsorbent on the path of the air flow to evaporate. Then, when it is determined by the determination means that the amount of decrease in the temperature of the adsorbent on the path through which the airflow flows is equal to or greater than the predetermined value, the path through which the airflow flows is determined by the path control means. The air flow path is changed so that the air flow flows along a different path. As a result, the evaporated fuel is desorbed from the adsorbent on the path where the air flow did not flow before the change, that is, the adsorbent in which the temperature has not decreased due to the desorption of the evaporated fuel, and is supplied to the intake system A decrease in the amount of evaporated fuel (amount of evaporated fuel in the canister) can be suppressed. Further, when the air flow path is changed, the air flow stops flowing in the path in which the air flow was flowing before the change, so that the adsorbent (adsorbent whose temperature decreased) on the path The temperature gradually increases after the change (becomes the same as the outside temperature). Therefore, even if the path is changed after the change and the air flow again flows along the path where the air flow was initially flowing, the amount of evaporated fuel supplied to the intake system is reduced. Can be suppressed. By sequentially changing the air flow path in this way, the evaporative fuel is always desorbed from the adsorbent that has not experienced a temperature drop due to the desorption of the evaporative fuel, thereby improving the evaporative fuel processing capacity. Can be made.

  In the fuel vapor processing apparatus, the canister has a plurality of adsorption chambers in which the adsorbent is accommodated, the plurality of paths are provided in the adsorption chambers different from each other, and the plurality of purge ports are purge pipes The purge pipe is formed by connecting a main pipe connected to the intake system and a plurality of branch pipes respectively connected to the plurality of purge ports via a switching valve. The switching valve can switch the communication state so that the main pipe of the purge pipe and any one of the plurality of branch pipes communicate with each other when the evaporated fuel is supplied to the intake system. It is preferable that the path control means includes the switching valve and switching valve control means for controlling the operation of the switching valve.

  Thus, the air flow path can be easily controlled and the air flow path can be easily changed by the switching valve provided in the purge pipe.

  In the evaporative fuel processing apparatus, the canister has a plurality of adsorption chambers in which the adsorbent is accommodated, the plurality of paths are provided in the adsorption chambers different from each other, and the plurality of drain ports have leading ends. A drain pipe that is open to the atmosphere is connected, the drain pipe is formed by connecting a main pipe on the tip side and a plurality of branch pipes respectively connected to the plurality of drain ports via a switching valve, The switching valve is configured to be able to switch the communication state so that the main pipe in the drain pipe and any one of the plurality of branch pipes communicate with each other when the evaporated fuel is supplied to the intake system. The path control means may be configured by the switching valve and switching valve control means for controlling the operation of the switching valve.

  Thus, the air flow path can be easily controlled by the switching valve provided in the drain pipe, and the air flow path can be easily changed.

  In the fuel vapor processing apparatus, the canister has one adsorption chamber in which the adsorbent is accommodated, the plurality of paths are provided in the adsorption chamber, and the plurality of purge ports are connected via a purge pipe. The purge pipe is connected to the main pipe connected to the intake system and a plurality of branch pipes respectively connected to the plurality of purge ports via a first switching valve. The first switching valve is in a communication state so that the main pipe of the purge pipe and any one of the plurality of branch pipes communicate with each other when the evaporated fuel is supplied to the intake system. The plurality of drain ports are connected to a drain pipe whose tip is open to the atmosphere, and the drain pipe is connected to the main pipe on the tip side and the plurality of drain ports, respectively. The plurality of branch pipes are connected via a second switching valve, and the second switching valve is configured to connect the main pipe and the plurality of branches in the drain pipe when the evaporated fuel is supplied to the intake system. The communication state is configured to be switchable so that any one of the branch pipes communicates, and the path control means includes the first and second switching valves, and the first and second switching valves. The purge port control means for controlling the operation of the valve may be configured, and the purge port may be disposed in the vicinity of the drain port not corresponding to the purge port.

  By doing so, the inside of the canister can be constituted by one adsorption chamber, and the canister can be reduced in size. In addition, the temperature decrease amount of the adsorbent near the drain port on the path in which the air flow is flowing is considerably smaller than the temperature decrease amount of the adsorbent near the purge port on the path (all adsorbents on the path). Is the smallest temperature drop). Therefore, by arranging the purge port in the vicinity of the drain port that does not correspond to the purge port, the portion that is in the vicinity of the purge port on the path through which the airflow flows after the change of the airflow path is It will be located in the vicinity of the portion where the amount of temperature decrease before the change is small, so that it is possible to suppress a decrease in the amount of evaporated fuel supplied to the intake system.

  In the evaporative fuel processing apparatus, estimation means for estimating the amount of evaporative fuel desorbed from the adsorbent on the path through which the airflow flows when the evaporative fuel is supplied to the intake system and supplied to the intake system The determination means is based on the amount of evaporated fuel estimated by the estimation means, and whether the amount of decrease in the temperature of the adsorbent on the path through which the airflow flows is equal to or greater than the predetermined value. Preferably, it is configured to determine whether or not.

  That is, the amount of decrease in the temperature of the adsorbent on the path through which the air flow flows corresponds to the amount of evaporated fuel desorbed from the adsorbent on the path and supplied to the intake system. Based on the above, it is possible to easily determine whether or not the amount of decrease in the temperature of the adsorbent on the path through which the airflow flows has become a predetermined value or more. The amount of evaporated fuel supplied to the intake system is, for example, the basic injection amount of fuel obtained from the intake air amount by the air flow sensor, and the A / F provided in the exhaust system of the internal combustion engine with respect to the basic injection amount. It can be easily estimated from the injection amount obtained by feeding back the fuel amount corresponding to the detection value by the sensor. Therefore, it is not necessary to provide a temperature sensor or the like, and the fuel vapor processing apparatus can be easily configured.

  The evaporative fuel processing apparatus further includes a temperature sensor disposed on one of the plurality of paths and detecting the temperature of the adsorbent on the path, and the determination means includes the temperature sensor In the case where the air flow is flowing along the arranged path, the amount of decrease in the temperature of the adsorbent on the path through which the air flow flows is determined based on the detection value by the temperature sensor. On the other hand, if the air flow is flowing along a path where the temperature sensor is not disposed, it is determined whether the air flow has started flowing along the path. It is determined that the amount of decrease in the temperature of the adsorbent is equal to or greater than the predetermined value after the time when the air flow is flowing along the path where the temperature sensor is disposed. Depending on whether it is more than the time until Then, it is configured to determine whether or not the amount of decrease in the temperature of the adsorbent on the path in which the airflow flows along the path where the temperature sensor is not disposed is equal to or greater than the predetermined value. It may be configured that

  As a result, when the air flow is flowing along the path where the temperature sensor is disposed, the amount of decrease in the temperature of the adsorbent on the path is greater than or equal to a predetermined value based on the detection value by the temperature sensor. It can be easily and accurately determined whether or not. Further, even when an air flow is flowing along a path where the temperature sensor is not disposed, the amount of decrease in the temperature of the adsorbent on the path becomes a predetermined value or more (that is, the adsorbent on the path). It is possible to easily determine whether or not the total amount of desorption has reached or exceeded the reference value. That is, the amount of evaporated fuel adsorbed on the adsorbent on the path not provided with the temperature sensor is set to be substantially the same as the amount of evaporated fuel adsorbed on the adsorbent on the path provided with the temperature sensor. Therefore, the method of lowering the temperature of the adsorbent on the path where the temperature sensor is not arranged is basically the same as the method of lowering the temperature of the adsorbent on the path where the temperature sensor is arranged. Be the same. Therefore, the elapsed time from the start of the air flow along the path where the temperature sensor is not provided is the elapsed time after the air flow is flowing along the path where the temperature sensor is provided. From the beginning, until it is determined that the temperature decrease amount of the adsorbent is equal to or greater than the predetermined value (the total desorption amount of the adsorbent on the path where the temperature sensor is disposed is equal to or greater than a reference value). The total desorption amount of the adsorbent on the path where the temperature sensor is not disposed becomes equal to or higher than the reference value, and the temperature of the adsorbent on the path where the temperature sensor is not disposed It can be determined that the amount of decrease is equal to or greater than the predetermined value. Therefore, it is not necessary to provide temperature sensors in all the paths, and the cost increase of the evaporated fuel processing apparatus can be suppressed as much as possible.

  The temperature sensor is preferably disposed in the vicinity of the purge port on one of the plurality of paths.

  That is, the adsorbent in the vicinity of the purge port on the path where the temperature sensor is disposed is the adsorbent having the largest temperature drop amount among all the adsorbents on the path. It is easy to detect the temperature decrease amount of the adsorbent in the vicinity of the purge port, and it becomes possible to more accurately determine whether or not the temperature decrease amount of the adsorbent on the path has become a predetermined value or more.

  As described above, according to the evaporative fuel processing apparatus of the present invention, the evaporative fuel is always desorbed from the adsorbent in which the temperature decrease due to the desorption of the evaporative fuel does not occur due to the change of the air flow path. Thereby, the processing capacity of the evaporated fuel can be improved. Therefore, even when the negative pressure generated in the canister is small due to the reduction of the pumping loss of the internal combustion engine, the evaporated fuel in the canister is sufficiently supplied to the intake system of the internal combustion engine. Can be prevented from being discharged.

It is the schematic which shows the evaporative fuel processing apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the control action of the 1st switching valve and purge valve by an engine controller. FIG. 3 is a view corresponding to FIG. 1 showing Embodiment 2 of the present invention. 6 is a flowchart showing a control operation of a first switching valve and a purge valve by an engine controller in Embodiment 2. It is FIG. 1 equivalent view which shows Embodiment 3 of this invention. It is FIG. 1 equivalent view which shows Embodiment 4 of this invention. 6 is a graph showing the relationship between the total purge flow rate from the start of purge and the total desorbed weight of evaporated fuel adsorbed by the adsorbent in the first and second adsorption chambers in the test apparatuses A to C. In test apparatus D, the temperature change of the adsorbent in the vicinity of the first purge port on the first path with respect to the time from the start of purge when the outside air temperature is 18.6 ° C., 35.0 ° C., 40.6 ° C. It is a graph which shows. In the test apparatus D, when the outside air temperature is 18.6 ° C., 35.0 ° C., 40.6 ° C., the total purge flow rate from the start of the purge and the evaporated fuel adsorbed by the adsorbent in the first adsorption chamber It is a graph which shows the relationship with the total desorption weight.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 schematically shows a fuel vapor processing apparatus according to Embodiment 1 of the present invention. This evaporative fuel processing device adsorbs evaporative fuel generated in a fuel tank (not shown) by an adsorbent such as activated carbon accommodated therein, and desorbs the adsorbed evaporative fuel from the adsorbent, A canister 1 for supplying an intake system of an engine (internal combustion engine) (not shown) is provided. The engine is provided with an exhaust gas recirculation device (EGR) and a variable timing mechanism (VVT) of an intake valve, thereby reducing the pumping loss of the engine.

  In the present embodiment, the canister 1 has a plurality of (two in the present embodiment) adsorption chambers 2 in which the adsorbent is accommodated. Hereinafter, these two adsorption chambers 2 are referred to as first and second adsorption chambers 2a and 2b. The first and second adsorption chambers 2a and 2b are respectively formed in two cases 3 independent of each other (hereinafter referred to as first and second cases 3a and 3b). These first and second cases The size, shape, and configuration of 3a, 3b (first and second adsorption chambers 2a, 2b) are the same, and the amount of adsorbent accommodated in each of the first and second adsorption chambers 2a, 2b is also the same. . Instead of forming the first and second adsorption chambers 2a and 2b in the first and second cases 3a and 3b independent of each other, the first and second adsorption chambers 2a and 2b are formed in one case 3, respectively. You may make it define (refer Embodiment 3 mentioned later).

  The first case 3a (first adsorption chamber 2a) corresponds to the first tank port 5a connected to the fuel tank, the first purge port 6a connected to the intake system, and the first purge port 6a. And a first drain port 7a that opens the inside of the first adsorption chamber 2a to the atmosphere. The first tank port 5a, the first purge port 6a, and the first drain port 7a are provided on the upper wall of the first case 3a (the upper wall of the first adsorption chamber 2a), and the first purge port 6a and the first drain port 7a is located on both sides of the first tank port 5a, which is located substantially at the center of the upper wall of the first case 3a.

  Similarly, the second case 3b (second adsorption chamber 2b) also includes a second tank port 5b connected to the fuel tank, a second purge port 6b connected to the intake system, and the second purge port 6b. And a second drain port 7b that opens the inside of the second adsorption chamber 2b to the atmosphere. The arrangement of the second tank port 5b, the second purge port 6b, and the second drain port 7b is the same as that of the first tank port 5a, the first purge port 6a, and the first drain port 7a.

  The first and second tank ports 5 a and 5 b are connected to the fuel tank via a tank connection pipe 11. The tank connection pipe 11 includes a main pipe 11a connected to the fuel tank, and first and second branch pipes branched from the main pipe 11a into two and connected to the first and second tank ports 5a and 5b, respectively. 11b, 11c. The evaporated fuel generated by evaporating in the fuel tank is divided approximately equally from the main pipe 11a to the first and second branch pipes 11b and 11c, and is supplied to the first and second tank ports 5a and 5b. The fuel flows into the adsorbing chambers 2a and 2b, respectively, and the evaporated fuel is adsorbed by the adsorbent in the first and second adsorbing chambers 2a and 2b.

  The first and second purge ports 6a and 6b are connected to the intake system (intake passage) via the purge pipe 12. The purge pipe 12 includes a main pipe 12a connected to the intake system and first and second branch pipes 12b and 12c connected to the first and second purge ports 6a and 6b, respectively. Connected through. The first switching valve 21 communicates between the main pipe 12a of the purge pipe 12 and any one of the first and second branch pipes 12b and 12c when the evaporated fuel is supplied to the intake system. The communication state can be switched. That is, the first switching valve 21 is in a state where the main pipe 12a and the first branch pipe 12b communicate with each other or when the main pipe 12a and the second branch pipe 12c communicate with each other when the evaporated fuel is supplied to the intake system. It is configured to switch to.

  The main pipe 12a of the purge pipe 12 is provided with a purge valve 25 that is opened and closed according to the engine operating state. The opening / closing operation of the purge valve 25 is controlled by the engine controller 51. When the purge valve 25 is opened, the evaporated fuel is supplied to the intake system. If the main pipe 12a and the first branch pipe 12b are in communication with each other by the first switching valve 21 when the evaporated fuel is supplied to the intake system, the first adsorption is performed via the main pipe 12a and the first branch pipe 12b. The inside of the chamber 2a has a negative pressure, whereby external air (air) is introduced into the first adsorption chamber 2a from the first drain port 7a, and the first adsorption port 2a has a first pressure from the first drain port 7a. An air flow flowing to the purge port 6a is generated. The evaporated fuel is desorbed from the adsorbent by the air flow, and the desorbed evaporated fuel is mixed with air and supplied to the intake system via the main pipe 12a and the first branch pipe 12b. The air flow is adapted to flow along a first path 18a provided in the first adsorption chamber 2a. That is, in the first adsorption chamber 2a, when an evaporated fuel is supplied to the intake system, an air flow flows from the first drain port 7a to the first purge port 6a via the adsorbent in the first adsorption chamber 2a. One path 18a is provided. The first path 18a is a path that is made as long as possible so that the air flow contacts substantially all of the adsorbent in the first adsorption chamber 2a, and a path forming wall 17 for forming such a path is provided. It is provided in the 1st adsorption | suction chamber 2a (The path | route formation wall 17 of FIG. 1 is shown typically).

  Similar to the first adsorption chamber 2a, the second adsorption chamber 2b passes through the adsorbent in the second adsorption chamber 2b from the second drain port 7b to the second purge port 6b when the evaporated fuel is supplied to the intake system. Thus, a second path 18b through which an air flow flows is provided. The shape and length of the second path 18b are the same as those of the first path 18a. If the main pipe 12a and the second branch pipe 12c are in communication with each other by the first switching valve 21 when the evaporated fuel is supplied to the intake system (when the purge valve 25 is opened), the main pipe 12a and The inside of the second adsorption chamber 2b becomes a negative pressure through the second branch pipe 12c, whereby an air flow flows along the second path 18b in the second adsorption chamber 2b.

  In the present embodiment, the first purge port 6a and the first drain port 7a (the second purge port 6b and the second drain port 7b) corresponding to each other in the canister 1 (in the first and second adsorption chambers 2a and 2b). Between the first drain port 7a and the first purge port 6a (from the second drain port 7b to the second purge port 6b) during the supply of the evaporated fuel to the intake system. The first path 18a (second path 18b) through which each flows is provided. The first switching valve 21 causes the air flow so that the air flow flows along one of the first and second paths 18a and 18b when the evaporated fuel is supplied to the intake system. Is controlled. The operation of the first switching valve 21 is controlled by the engine controller 51. Thus, the first switching valve 21 and the engine controller 51 as switching valve control means for controlling the operation of the first switching valve 21 constitute the path control means of the present invention.

  The engine controller 51 is a controller based on a well-known microcomputer, and includes a central processing unit (CPU) that executes a program, a memory that is configured by, for example, RAM and ROM, and stores a program and data, And an input / output (I / O) bus for inputting and outputting signals.

  The engine controller 51 includes at least a signal related to the intake air flow from the air flow sensor 31, a crank angle pulse signal from the crank angle sensor 32, a throttle opening signal from the throttle opening sensor 33 that detects the amount of depression of the accelerator pedal, a vehicle speed. The vehicle speed signal from the sensor 34 and the signal from the A / F sensor 35 which is provided in the exhaust system of the engine and outputs a signal corresponding to the oxygen concentration in the gas are input. Based on these input signals, the engine controller 51 controls the operation of an injector 41 (actuator) that injects fuel into the cylinder of the engine, the purge valve 25, a spark plug (not shown), and the like. The operation of the 1 switching valve 21 is controlled.

  Based on the input signal, the engine controller 51 determines whether or not the engine operation state is in a preset purge execution region. When the engine operation state is in the purge execution region, the engine controller 51 sets the purge valve 25. On the other hand, when not in the purge execution area, the purge valve 25 is closed.

  The fuel injection amount injected from the injector 41 when the purge valve 25 is closed is a basic injection amount obtained from the intake air amount by the air flow sensor 31. The engine controller 51 controls the injector 41 (actuator) so as to inject fuel with this basic injection amount.

  On the other hand, the fuel injection amount injected from the injector 41 when the purge valve is open is the same as the basic injection amount when the detected value by the A / F sensor 35 is a preset value (when the purge valve 25 is closed). Therefore, the fuel injection amount is obtained by feeding back the fuel amount corresponding to the detected value by the A / F sensor 35 with respect to the basic injection amount so as to be the same value as when the fuel is injected). The injection amount obtained by this feedback is smaller than the basic injection amount by the amount of evaporated fuel supplied to the intake system by purging. Therefore, by subtracting the injection amount obtained by the feedback from the basic injection amount, the amount of evaporated fuel supplied to the intake system by purging can be found. The engine controller 51 uses a path (first path 18a or second path 18b) through which the air flow flows when the evaporated fuel is supplied to the intake system from the basic injection amount and the injection amount obtained by the feedback. The amount of evaporated fuel desorbed from the upper adsorbent and supplied to the intake system is estimated, and the operation of the first switching valve 21 is controlled based on the amount of evaporated fuel. Thus, the engine controller 51 constitutes the estimation means of the present invention.

  Based on the estimated amount of evaporated fuel, the engine controller 51 adjusts the adsorbent on the path through which the airflow flows (in particular, when the airflow is flowing along the first path 18a, the first The adsorbent in the vicinity of the first purge port 6a on the path 18a is preferable, and when the air flow is flowing along the second path 18b, the adsorbent in the vicinity of the second purge port 6b on the second path 18b is preferable. ) Is determined whether or not the temperature decrease amount is equal to or greater than a predetermined value. That is, when the evaporated fuel is desorbed from the adsorbent on the path through which the airflow flows and the desorbed evaporated fuel is supplied to the intake system, it is adsorbed by the adsorbent in a liquid state. The evaporated fuel is vaporized and desorbed from the adsorbent. At this time, the temperature of the adsorbent decreases because the vaporized fuel loses heat of vaporization. In particular, when an air flow is flowing along the first path 18a, the adsorbent near the first purge port 6a on the first path 18a immediately after the evaporated fuel is desorbed, the first drain port 7a. Since the evaporated fuel flowing from the side is adsorbed and the adsorbed evaporated fuel is desorbed, the evaporative fuel is frequently adsorbed and desorbed, so that the temperature greatly decreases. When an air flow is flowing along the second path 18b, the temperature of the adsorbent near the second purge port 6b on the second path 18b is also greatly reduced. The amount of decrease in the temperature of the adsorbent on the path in which the air flow is flowing corresponds to the amount of evaporated fuel that is desorbed from the adsorbent on the path and is supplied to the intake system. That is, whether or not the amount of decrease in the temperature of the adsorbent on the path through which the airflow flows is equal to or greater than the predetermined value when the fuel vapor amount is equal to or greater than the predetermined amount (CONST in the flowchart described later). Determine. By examining the correspondence between the predetermined amount and the predetermined value in advance, the temperature decrease amount can be determined based on the estimated evaporated fuel amount. In particular, the adsorbent in the vicinity of the purge port on the path through which the air flow flows is the adsorbent having the largest temperature drop amount among all the adsorbents on the path, and thus the correspondence is clear. The determination of the temperature drop amount can be performed accurately. The engine controller 51 constitutes the determination means of the present invention.

  The predetermined value may be a constant value or may be set in consideration of outside air temperature information from an outside air temperature sensor (not shown) that detects the outside air temperature. For example, the predetermined value is decreased as the outside air temperature detected by the outside air temperature sensor is lower.

  When the amount of decrease in the temperature of the adsorbent becomes too large, the evaporated fuel adsorbed by the adsorbent becomes difficult to vaporize (are difficult to desorb), and the amount of evaporated fuel supplied to the intake system decreases. In order to suppress the decrease in the evaporated fuel amount, the engine controller 51 determines the temperature decrease amount, and when it is determined that the temperature decrease amount is equal to or greater than the predetermined value, the first switching valve 21 is used. The air flow path is changed so that the air flow flows along a path different from the path through which the air flow flows. That is, for example, when the main switch 12a of the purge pipe 12 and the first branch pipe 12b are in communication with each other by the first switching valve 21, the engine controller 51 determines that the temperature decrease amount is equal to or greater than the predetermined value. When the determination is made, the first switching valve 21 is operated so that the main pipe 12a and the second branch pipe 12c communicate with each other. As a result, the path of the air flow is changed from the first path 18a to the second path 18b, and this time, the adsorbent on the second path 18b, that is, the adsorbent that has not undergone a temperature decrease due to desorption of the evaporated fuel is evaporated. The fuel comes off. Therefore, it is possible to suppress a decrease in the amount of evaporated fuel supplied to the intake system.

  The control operation of the first switching valve 21 and the purge valve 25 by the engine controller 51 will be described with reference to the flowchart of FIG.

  In the first step S1, signals from various sensors are input, and in the next step S2, it is determined whether or not the engine operating state is in the purge execution region. When the determination in step S2 is YES, the process proceeds to step S3. When the determination in step S2 is NO, the process proceeds to step S16.

  In the above step S3, it is determined whether or not the purge is being executed from the previous time (whether or not the determination in the previous step S2 was also YES). When the determination in step S3 is NO, the process proceeds to step S4. If the determination in step S3 is yes, the process proceeds to step S5.

  In step S4, the first switching valve 21 is switched to the first adsorption chamber 2a side (the main pipe 12a of the purge pipe 12 and the first branch pipe 12b are in communication), the purge valve 25 is opened, and then the process returns. . That is, when purging is performed from this time (when the determination in the previous step S2 is NO), the air flow is caused to flow along the first path 18a in the first adsorption chamber 2a. In addition, when performing a purge from this time, it is not always necessary that the air flow flows along the first path 18a, but the air flow flows along the second path 18b in the second adsorption chamber 2b ( The first switching valve 21 may be switched to the second adsorption chamber 2b side).

  In step S5 that proceeds when the determination in step S3 is YES, whether or not the first switching valve 21 is on the first adsorption chamber 2a side (whether the main pipe 12a and the first branch pipe 12b are in communication). Or not). When the determination in step S5 is YES, the process proceeds to step S6, while when the determination in step S5 is NO, the process proceeds to step S11.

  In step S6, the amount of evaporated fuel per unit time desorbed from the adsorbent on the first path 18a and supplied to the intake system is calculated from the basic injection amount and the injection amount obtained by the feedback. The amount of evaporated fuel per unit time is calculated by multiplying the amount of evaporated fuel per unit time by the time from the previous calculation time to the current calculation time, thereby calculating the evaporated fuel amount ΔFA for the current purge.

  In step S7 following step S6, ΔFA is added to the previous accumulated evaporated fuel amount FA stored in the memory of the engine controller 51, and the accumulated evaporated fuel amount FA up to this time is added. In the next step S8, it is determined whether or not the accumulated evaporated fuel amount FA up to this time is equal to or greater than a predetermined amount CONST. That is, it is determined whether or not the amount of decrease in the temperature of the adsorbent on the first path 18a in which the airflow is flowing is equal to or greater than the predetermined value.

  When the determination in step S8 is NO, that is, when it is determined that the amount of decrease in the temperature of the adsorbent on the first path 18a is not equal to or greater than the predetermined value, the process proceeds to step S9 and integration up to this time is performed. The fuel vapor amount FA is stored in the memory, and then the process returns. On the other hand, when the determination in step S8 is YES, that is, when it is determined that the amount of decrease in the temperature of the adsorbent on the first path 18a is equal to or greater than the predetermined value, the process proceeds to step S10 and the first switching valve 21 is reached. Is switched to the second adsorption chamber 2b side (a state in which the main pipe 12a and the second branch pipe 12c are in communication), the storage of the accumulated evaporated fuel amount FA by the memory is cleared, and then the process returns.

  In step S11 that proceeds when the determination in step S5 is NO, as in step S6, the desorption from the adsorbent on the second path is performed based on the basic injection amount and the injection amount obtained by the feedback. Calculate the amount of evaporated fuel per unit time supplied to the intake system, and multiply the amount of evaporated fuel per unit time by the time from the previous calculation to the current calculation. An evaporated fuel amount ΔFB is calculated.

  In step S12 following step S11, ΔFB is added to the previous accumulated evaporated fuel amount FB stored in the memory, and the accumulated evaporated fuel amount FB is updated as the current accumulated evaporated fuel amount FB. In step S13, it is determined whether or not the accumulated evaporated fuel amount FB up to this time is equal to or greater than a predetermined amount CONST. That is, it is determined whether or not the amount of decrease in the temperature of the adsorbent on the second path 18b in which the airflow is flowing is equal to or greater than the predetermined value.

  When the determination in step S13 is NO, that is, when it is determined that the amount of decrease in the temperature of the adsorbent on the second path 18b is not equal to or greater than the predetermined value, the process proceeds to step S14 and integration up to this time is performed. The fuel vapor amount FB is stored in the memory, and then the process returns. On the other hand, when the determination in step S13 is YES, that is, when it is determined that the amount of decrease in the temperature of the adsorbent on the second path 18b is equal to or greater than the predetermined value, the process proceeds to step S15, and the first switching valve 21 is reached. Is switched to the first adsorption chamber 2a side (a state in which the main pipe 12a and the first branch pipe 12b are in communication), the storage of the accumulated evaporated fuel amount FB by the memory is cleared, and then the process returns.

  In step S16 that proceeds when the determination in step S2 is NO, the purge valve 25 is closed, and in the next step S17, the storage of the accumulated evaporated fuel amounts FA and FB by the memory is cleared, and then the process returns.

  By the control operation of the engine controller 51, the first switching valve 21 is switched to the first adsorption chamber 2a side, and the evaporated fuel is desorbed from the adsorbent on the first path 18a in the first adsorption chamber 2a. When the desorbed evaporated fuel is supplied to the intake system, the temperature of the adsorbent on the first path 18a (particularly, the temperature of the adsorbent near the first purge port 6a on the first path 18a) decreases. (The initial temperature is about the same as the outside temperature). If the temperature drop amount is equal to or greater than the predetermined value, the evaporated fuel adsorbed by the adsorbent on the first path 18a becomes difficult to vaporize, and the evaporated fuel amount supplied to the intake system decreases. However, in the present embodiment, when it is determined that the temperature decrease amount is equal to or greater than the predetermined value (when the integrated evaporated fuel amount FA is equal to or greater than the predetermined amount CONST), the first switching valve 21 performs the second adsorption. Switched to the chamber 2a side, this time, the evaporated fuel is desorbed from the adsorbent on the second path 18b in the second adsorption chamber 2a, and the desorbed evaporated fuel is supplied to the intake system. Since the air flow did not flow through the second path 18b, the temperature of the adsorbent on the second path 18b is approximately the same as the outside air temperature. Therefore, by switching the path through which the airflow flows from the first path 18a to the second path 18b, it is possible to suppress a decrease in the amount of evaporated fuel supplied to the intake system.

  Further, when the evaporated fuel is desorbed from the adsorbent on the second path 18b in the second adsorption chamber 2b and the desorbed evaporated fuel is supplied to the intake system, the adsorbent on the second path 18b The temperature decreases, but when it is determined that the amount of temperature decrease is equal to or greater than the predetermined value (when the accumulated evaporated fuel amount FB is equal to or greater than the predetermined amount CONST), the first switching valve 21 is again turned on. It is switched to the one adsorption chamber 2a side, and the evaporated fuel is desorbed again from the adsorbent on the first path 18a, and the desorbed evaporated fuel is supplied to the intake system.

  Here, while the evaporated fuel is desorbed from the adsorbent on the second path 18b and the desorbed evaporated fuel is supplied to the intake system, the temperature of the adsorbent on the first path 18a is such that the air flow is It gradually rises because it is not flowing. As a result, when the first switching valve is switched again to the first adsorption chamber 2a side, the temperature of the adsorbent on the first path 18a is normally approximately the same as the outside air temperature. Therefore, by alternately switching the air flow path to the first path 18a or the second path 18b, the evaporated fuel is always desorbed from the adsorbent in which the temperature drop due to the desorption of the evaporated fuel has not occurred. The processing capability of the evaporated fuel (the capability of supplying the evaporated fuel to the intake system) can be improved.

  Therefore, even if the negative pressure generated in the canister 1 (first and second adsorption chambers 2a, 2b) is small due to the reduction of the pumping loss of the engine, the evaporated fuel in the first and second adsorption chambers 2a, 2b is Thus, it is possible to prevent the evaporated fuel from being discharged into the atmosphere from the first and second drain ports 7a and 7b.

(Embodiment 2)
FIG. 3 shows a second embodiment of the present invention (in the following embodiments, the same parts as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted), and an air flow flows. The method for determining whether or not the amount of decrease in the temperature of the adsorbent on the route that has reached the predetermined value or more is different from that of the first embodiment.

  That is, in the present embodiment, the portion is located near the purge port on one of the first and second paths 18a and 18b (in the present embodiment, near the first purge port 6a on the first path 18a). A temperature sensor 38 for detecting the temperature of the adsorbent is disposed. Except for the fact that the temperature sensor 38 is provided, the configuration of the canister 1 is the same as that of the first embodiment. A temperature signal from the temperature sensor 38 is input to the engine controller 51.

  As in the first embodiment, the engine controller 51 detects at least a signal related to the intake air flow from the air flow sensor 31, a crank angle pulse signal from the crank angle sensor 32, and a throttle opening sensor 33 that detects the amount of depression of the accelerator pedal. The throttle opening signal from the vehicle, the vehicle speed signal from the vehicle speed sensor 34, and the signal from the A / F sensor 35 are input. Based on these input signals, the engine controller 51 controls operations of an injector 41 (actuator) that injects fuel into the cylinders of the engine, a purge valve 25, a spark plug (not shown), and the like. The engine controller 51 also receives a temperature signal from the temperature sensor 38 and controls the operation of the first switching valve 21 as will be described later based on the temperature signal.

  When the air flow is flowing along the first path 18a in which the temperature sensor 38 is disposed, the engine controller 51 determines that the air flow is based on the detection value (the temperature signal) detected by the temperature sensor 38. It is determined whether the amount of decrease in the temperature of the adsorbent on the flowing first path 18a is equal to or greater than the predetermined value.

  On the other hand, if the air flow is flowing along the second path 18b where the temperature sensor 38 is not disposed, the engine controller 51 has elapsed since the air flow started flowing along the second path 18b. The time from when the air flow starts flowing along the first path 18a until when it is determined that the amount of decrease in the temperature of the adsorbent is equal to or greater than the predetermined value. It is determined whether or not the amount of decrease in the temperature of the adsorbent on the second path 18b has become equal to or greater than the predetermined value depending on whether or not it is time or more. That is, the amount of the adsorbent on the second path 18b is the same as the amount of the adsorbent on the first path 18a, and the evaporated fuel from the fuel tank is substantially evenly distributed in the first and second adsorption chambers 2a and 2b. Since it flows in, the amount of evaporated fuel adsorbed by the adsorbent on the second path 18b is substantially the same as the amount of evaporated fuel adsorbed by the adsorbent on the first path 18a. Thereby, the method of lowering the temperature of the adsorbent on the second path 18b is basically the same as the method of lowering the temperature of the adsorbent on the first path 18a. Therefore, the elapsed time after the air flow starts flowing along the second path 18b is equal to the temperature of the adsorbent after the air flow starts flowing along the first path 18a. When the time until it is determined that the amount of decrease is equal to or greater than the predetermined value is reached, it can be determined that the amount of decrease in the temperature of the adsorbent on the second path 18b is equal to or greater than the predetermined value.

  The control operation of the first switching valve 21 and the purge valve 25 by the engine controller 51 will be described with reference to the flowchart of FIG.

  In the first step S31, signals from various sensors are input, and in the next step S32, it is determined whether or not the engine operating state is in the purge execution region. When the determination in step S32 is YES, the process proceeds to step S33, while when the determination in step S32 is NO, the process proceeds to step S47.

  In the above step S33, it is determined whether or not the purge is being executed from the previous time (whether or not the determination in the previous step S32 was also YES). If the determination in this step S33 is NO, the process proceeds to step S34. If the determination in step S33 is yes, the process proceeds to step S37.

    In step S34, the first switching valve 21 is switched to the first adsorption chamber 2a side and the purge valve 25 is opened. In the present embodiment, when purging is performed from this time (when the determination in the previous step S32 is NO), an air flow always flows along the first path 18a in which the temperature sensor 38 is disposed. Like that.

  In the next step S35, the input temperature from the temperature sensor 38 in the step S31 is stored in the memory as the starting temperature T0, and in the next step S36, the total desorbed amount of the adsorbent on the first path 18a. Starts counting the timer TIM to estimate, and then returns.

  In step S37 that proceeds when the determination in step S33 is YES, it is determined whether or not the first switching valve 21 is on the first adsorption chamber 2a side. When the determination in step S37 is YES, the process proceeds to step S38, while when the determination in step S5 is NO, the process proceeds to step S42.

  In step S38, the input temperature from the temperature sensor 38 in step S31 is compared with the start temperature T0, and it is determined whether or not the temperature decrease amount from the start temperature T0 is equal to or greater than the predetermined value. To do.

  When the determination in step S38 is NO, the process proceeds to step S39, the timer TIM is counted up, and then the process returns.

  On the other hand, when the determination in step S38 is YES, the process proceeds to step S40, the timer TIM is stopped, and the timer TIM at the time of stop is stored in the memory. The value of the timer TIM at the time of stopping is such that the amount of decrease in the temperature of the adsorbent on the first path 18a becomes equal to or more than the predetermined value after the air flow starts flowing along the first path 18a (that is, the first Time until it is determined that the total desorption amount of the adsorbent on the path 18a is equal to or greater than the reference value).

  In the next step S41, the first switching valve 21 is switched to the second adsorption chamber 2b side, and then the process returns.

  In step S42 that proceeds when the determination in step S37 is NO, the timer TIM stored in the memory (the timer TIM stored in step S40 or step S45 described later) is read, and in the next step S43, Count down timer TIM.

  In the next step S44, it is determined whether or not the timer TIM is zero. That is, the elapsed time from the start of the air flow along the second path 18b is equal to the amount of decrease in the temperature of the adsorbent on the first path 18a after the air flow starts flowing along the first path 18a. It is determined whether or not the time until it is determined that the value is equal to or greater than the value (the total desorption amount of the adsorbent on the first path 18a is equal to or greater than the reference value) is determined. That is, the method of lowering the temperature of the adsorbent on the second path 18b is basically the same as the method of lowering the temperature of the adsorbent on the first path 18a, so the timer TIM becomes zero. The total desorption amount of the adsorbent on the second path 18b is equal to or higher than the reference value, and it is determined that the temperature decrease amount of the adsorbent on the second path 18b is equal to or higher than the predetermined value. it can. When the determination in step S44 is NO, the process proceeds to step S45, the timer TIM is stored in the memory, and then the process returns.

  On the other hand, when the determination in step S44 is YES, the process proceeds to step S46, the first switching valve 21 is switched to the first adsorption chamber 2a side, and then the process returns.

  In step S47 that proceeds when the determination in step S32 is NO, the purge valve 25 is closed, and in the next step S48, the storage of the timer TIM by the memory is cleared, and then the process returns.

  Therefore, in the present embodiment, when the air flow is flowing along the first path 18a in which the temperature sensor 38 is disposed, the first path is based on the detection value (the temperature signal) detected by the temperature sensor 38. It can be easily and accurately determined whether or not the amount of decrease in the temperature of the adsorbent on 18a has reached a predetermined value or more. In addition, even when the air flow is flowing along the second path 18b where the temperature sensor 38 is not disposed, the adsorbent on the first path 18a starts after the air flow starts flowing along the first path 18a. Using the time until it is determined that the temperature decrease amount is equal to or greater than the predetermined value, it is easily determined whether or not the temperature decrease amount of the adsorbent on the second path 18b is equal to or greater than the predetermined value. be able to. Therefore, it is not necessary to arrange the temperature sensor 38 in both the first and second paths 18a and 18b, and the cost increase of the evaporated fuel processing apparatus can be suppressed as much as possible.

  In the second embodiment, the temperature sensor 38 is disposed in the vicinity of the first purge port 6a on the first path 18a. However, the temperature sensor 38 may be disposed anywhere on the first path 18a. . However, since the adsorbent in the vicinity of the first purge port 6a on the first path 18a is the adsorbent having the largest temperature decrease amount among all the adsorbents on the first path 18a, it is easy to detect the temperature decrease amount. From the viewpoint of more accurately determining whether or not the amount of decrease in the temperature of the adsorbent on the first path 18a has reached a predetermined value or more, it is disposed in the vicinity of the first purge port 6a on the first path 18a. preferable. Even if it cannot be arranged in the vicinity of the first purge port 6a on the first path 18a, it is preferable to provide it as close to the first purge port 6a as possible on the first path 18a. The same applies to the case where the temperature sensor 38 is disposed on the second path 18b.

  Further, the temperature sensor 38 may be disposed on each of the first and second paths 18a and 18b. In this case, even when an air flow is flowing along the second path 18b, detection by the temperature sensor 38 provided on the second path 18b is performed in the same manner as when the air flow is flowing along the first path 18a. Based on the value, it may be determined whether or not the amount of decrease in the temperature of the adsorbent on the second path 18b is equal to or greater than the predetermined value.

(Embodiment 3)
FIG. 5 shows Embodiment 3 of the present invention. Instead of providing the first switching valve 21 in the purge pipe 12, the second switching valve 22 is connected to the drain pipe 13 connected to the first and second drain ports 7a and 7b. Is provided.

  That is, in the present embodiment, the first and second adsorption chambers 2a and 2b in which the adsorbent that adsorbs the evaporated fuel from the fuel tank are accommodated in the case 3 so as to face each other in the horizontal direction. A partition wall 28 is defined as a partition wall. First and second drain ports 7a and 7b are respectively provided at the lower ends of the opposing portions of the two partition walls 28 facing in the horizontal direction. A drain pipe 13 whose tip is open to the atmosphere is connected to the first and second drain ports 7a and 7b. The drain pipe 13 is connected through a second switching valve 22 to a main pipe 13a on the distal end side and first and second branch pipes 13b and 13c connected to the first and second drain ports 7a and 7b, respectively. It becomes. The second switching valve 22 is disposed in a space between the facing portions of the two partition walls 28 in the case 3. A main pipe 13 a of the drain pipe 13 extends downward from the second switching valve 22, penetrates the lower wall of the case 3, and projects downward. As in the first and second embodiments, the first and second adsorption chambers 2a and 2b can be formed in the first and second cases 3a and 3b that are independent from each other.

  In the present embodiment, there is nothing corresponding to the first switching valve 21 of the first and second embodiments, and the first and second branch pipes 12b and 12c of the purge pipe 12 branch directly from the main pipe 12a.

  The first and second tank ports 5a and 5b are respectively provided at the opposite ends of the partition wall 28 on the upper walls of the first and second adsorption chambers 2a and 2b, and are the same as in the first embodiment. In addition, it is connected to the fuel tank via the tank connection pipe 11. The first and second purge ports 6a and 6b are respectively provided at the ends of the upper walls of the first and second adsorption chambers 2a and 2b opposite to the opposing portions, and the first and second purge ports 6a and 6b The second branch pipes 12b and 12c are connected to each other.

  The second switching valve 22 communicates with the main pipe 13a in the drain pipe 13 and any one of the first and second branch pipes 13b and 13c when the evaporated fuel is supplied to the intake system. The communication state can be switched. That is, the second switching valve 22 is in a state in which the main pipe 13a and the first branch pipe 13b communicate with each other or in a state in which the main pipe 13a and the second branch pipe 13c communicate with each other when the evaporated fuel is supplied to the intake system. It is configured to switch to.

  In the present embodiment, the second switching valve 22 can be switched to a state in which the main pipe 13a of the drain pipe 13 and the branch pipes 13b and 13c communicate with each other, and the evaporated fuel is supplied to the intake system. When not supplied (when the purge valve 25 is closed), the main pipe 13a and the two branch pipes 13b and 13c are switched to a communication state. The operation of the second switching valve 22 is controlled by the engine controller 51. In the present embodiment, the second switching valve 22 and the engine controller 51 as switching valve control means for controlling the operation of the second switching valve 22 constitute the path control means of the present invention.

  When the purge valve 25 is closed, the main pipe 13a of the drain pipe 13 and the first and second branch pipes 13b, 13c are in communication with each other by the second switching valve 22, so that the first and second adsorption chambers 2a, The pressure in 2b will be the same. As a result, the evaporated fuel generated by evaporating in the fuel tank is divided approximately equally from the main pipe 11a of the tank connection pipe 11 to the first and second branch pipes 11b and 11c, and the first and second tank ports 5a, 5b flows into the first and second adsorption chambers 2a and 2b, respectively, and the vaporized fuel that has flowed in is adsorbed by the adsorbent in the first and second adsorption chambers 2a and 2b.

  Suppose that the main pipe 13a of the drain pipe 13 and the first branch pipe 13b are in communication with each other by the second switching valve 22 when the evaporated fuel is supplied to the intake system (when the purge valve 25 is opened). Outside air (air) is introduced into the first adsorption chamber 2a from the first drain port 7a, and from the first drain port 7a to the first purge port 6a along the first path 18a in the first adsorption chamber 2a. Airflow flows toward you. On the other hand, assuming that the main pipe 13a and the second branch pipe 13c are in communication with each other by the second switching valve 22, outside air (air) is introduced into the second adsorption chamber 2b from the second drain port 7b, and the second In the adsorption chamber 2b, an air flow flows from the second drain port 7b toward the second purge port 6b along the second path 18b. The first and second paths 18a and 18b are symmetrical with respect to a plane that passes through the center of the first and second suction chambers 2a and 2b in the case 3 in the opposing direction and is perpendicular to the opposing direction.

  As in the first and second embodiments, the engine controller 51 detects at least a signal related to the intake air flow from the air flow sensor 31, a crank angle pulse signal from the crank angle sensor 32, and a throttle opening for detecting the amount of depression of the accelerator pedal. A throttle opening signal from the sensor 33, a vehicle speed signal from the vehicle speed sensor 34, and a signal from the A / F sensor 35 are input. Based on these input signals, the engine controller 51 controls the operation of an injector 41 (actuator) that injects fuel into the cylinder of the engine, the purge valve 25, a spark plug (not shown), and the like, and the second switching valve 22. Control the operation of Control operations of the second switching valve 22 and the purge valve 25 by the engine controller 51 are the same as those in the first embodiment (see the flowchart in FIG. 2).

  As in the second embodiment, a temperature sensor 38 for detecting the temperature of the adsorbent in the portion is disposed in the vicinity of the purge port on one of the first and second paths 18 and 18b. The control operation of the second switching valve 22 and the purge valve 25 by the engine controller 51 may be the same as in the second embodiment (the flowchart in FIG. 4).

  Therefore, in the present embodiment, the air flow path is easily controlled by the second switching valve 22 provided in the drain pipe 13 as in the first switching valve 21 provided in the purge pipe 12 of the first embodiment. And the air flow path can be easily changed.

(Embodiment 4)
FIG. 6 shows Embodiment 4 of the present invention, in which the first and second paths 18a, 18b are provided in one adsorption chamber 2. In FIG.

  That is, in the present embodiment, the canister 1 has only one adsorption chamber 2 provided in one case 3, and an adsorbent that adsorbs evaporated fuel from the fuel tank is adsorbed in the adsorption chamber 2. Contained. One tank port 5 to which the tank connection pipe 11 from the fuel tank is connected to the upper wall of the case 3 (the upper wall of the adsorption chamber 2), and the first and second branch pipes 12b and 12c of the purge pipe 12 are provided. First and second purge ports 6a and 6b connected to each other, and first and second drain ports 7a and 7b respectively connected to the first and second branch pipes 13b and 13c of the drain pipe 13 are provided. Yes.

  The tank port 5 is located substantially at the center of the upper wall of the case 3, the first and second purge ports 6 a and 6 b are located on both sides of the tank port 5, and the first and second drains The ports 7a and 7b are located on both sides of the two purge ports 6a and 6b.

  The first purge port 6a and the first drain port 7a located on the opposite side of the tank port 5 from the first purge port 6a correspond to each other, and correspond to each other in the canister 1 (adsorption chamber). A first air flow flows between the first purge port 6a and the first drain port 7a via the adsorbent from the first drain port 7a to the first purge port 6a when the evaporated fuel is supplied to the intake system. A path 18a is provided.

  Further, the second purge port 6b and the second drain port 7b located on the opposite side of the tank port 5 from the second purge port 6b correspond to each other, and the above in the canister 1 (adsorption chamber). Between the second purge port 6b and the second drain port 7b corresponding to each other, an air flow flows through the adsorbent from the second drain port 7b to the second purge port 6b when the evaporated fuel is supplied to the intake system. A second path 18b is provided. The first path 18 a and the second path 18 b intersect at the lower position of the tank port 5.

  In the present embodiment, in addition to the first switching valve 21 provided in the purge pipe 12 as in the first and second embodiments, the second switching valve is provided in the drain pipe 13 as in the third embodiment. 22 is provided. The configurations of the purge pipe 12 and the first switching valve 21 are the same as those of the first and second embodiments, and the configurations of the drain pipe 13 and the second switching valve 22 are the same as those of the third embodiment (of the drain pipe 13). The arrangement positions and shapes of the first and second branch pipes 13b and 13c are different from those of the second embodiment). The operation of the first and second switching valves 21 and 22 is controlled by the engine controller 51.

  When the purge valve 25 is closed, the main pipe 13a of the drain pipe 13 and the both branch pipes 13b and 13c are in communication with each other by the second switching valve 22, and the evaporated fuel generated by evaporation in the fuel tank is stored in the tank. It flows into the adsorption chamber 2 from the port and spreads substantially uniformly in the adsorption chamber 2. At this time, the first switching valve 21 may cause the main pipe 12a of the purge pipe 12 and the first branch pipe 12b to communicate with each other, or the main pipe 12a and the second branch pipe 12c may communicate with each other. Good.

  When the evaporated fuel is supplied to the intake system (when the purge valve 25 is opened), the first switching valve 21 causes the main pipe 12a of the purge pipe 12 and the first branch pipe 12b to communicate with each other; A state in which the main pipe 13a and the first branch pipe 13b of the drain pipe 13 are in communication with each other by the second switching valve 22, or a state in which the main pipe 12a and the second branch pipe 12c are in communication with each other through the first switching valve 21; In addition, the second switching valve 22 brings the main pipe 13a and the second branch pipe 13c into communication. When the first switching valve 21 is in a state where the main pipe 12a and the first branch pipe 12b are in communication and the second switching valve 22 is in a state where the main pipe 13a and the first branch pipe 13b are in communication, the adsorption chamber 2, an air flow flows from the first drain port 7a toward the first purge port 6a along the first path 18a. Further, when the main switch 12a and the second branch pipe 12c are in communication with each other by the first switching valve 21, and the main pipe 13a and the second branch pipe 13c are in communication with each other by the second switching valve 22, In the adsorption chamber 2, an air flow flows from the second drain port 7b toward the second purge port 6b along the second path 18b.

  The first purge port 6a is disposed in the vicinity of the second drain port 7b that does not correspond to the first purge port 6a, and the second purge port 6b does not correspond to the second purge port 6b. It is disposed in the vicinity of the first drain port 7a. That is, the adsorbent in the vicinity of the first drain port 7a on the first path 18a has a temperature decrease amount among all the adsorbents on the first path 18a when the air flow is flowing along the first path 18a. The adsorbent in the vicinity of the second drain port 7b on the second path 18b, which is the smallest adsorbent, is among all the adsorbents on the second path 18b when the air flow is flowing along the second path 18b. The adsorbent has the smallest temperature drop. Accordingly, the first purge port 6a is disposed in the vicinity of the second drain port 7b, so that when the path through which the air flow flows is changed from the second path 18b to the first path 18a, the first purge port 6a is on the first path 18a. Since the portion near the first purge port 6a is located in the vicinity of the portion where the amount of temperature decrease before the change is small, the temperature of the adsorbent near the first purge port 6a on the first path 18a is almost the same. It is considered that the temperature is not lowered and is close to the outside air temperature. Therefore, it is possible to suppress a decrease in the amount of evaporated fuel supplied to the intake system. Similarly, when the second purge port 6b is disposed in the vicinity of the first drain port 7a, the intake air flow is changed even when the path through which the airflow flows is changed from the first path 18a to the second path 18b. A reduction in the amount of evaporated fuel supplied to the system can be suppressed.

  The control operation by the engine controller 51 is the same as that in the first embodiment (the flowchart in FIG. 2). However, in steps S4 and S15 in FIG. 2, instead of the operation of “switching the first switching valve 21 to the first adsorption chamber”, the first switching valve 21 is replaced with the main pipe 12a and the first branch pipe 12b of the purge pipe 12. And the second switching valve 22 is in a state where the main pipe 13a of the drain pipe 13 and the first branch pipe 13b are in communication with each other. In Step S10, instead of the operation of “switching the first switching valve to the second adsorption chamber”, the first switching valve 21 is brought into a state where the main pipe 12a of the purge pipe 12 and the second branch pipe 12c are in communication. In addition, the second switching valve 22 is operated so that the main pipe 13a of the drain pipe 13 and the second branch pipe 13c are in communication with each other.

  Alternatively, as in the second embodiment, a temperature sensor 38 that detects the temperature of the adsorbent in the portion is disposed in the vicinity of the purge port on one of the first and second paths 18a and 18b. The control operation by the engine controller 51 may be the same as that in the second embodiment (the flowchart in FIG. 4).

  Therefore, in the present embodiment, the inside of the canister 1 can be constituted by one adsorption chamber 2, the canister 1 can be reduced in size, and a decrease in the amount of evaporated fuel supplied to the intake system is suppressed. Can do.

  The present invention is not limited to the embodiment described above, and can be substituted without departing from the spirit of the claims.

  For example, in each of the above embodiments, there are two pairs of purge ports and drain ports corresponding to each other, and an air flow path is provided between each pair of purge ports and drain ports in the canister 1. Although there are two paths in total, three or more purge ports and drain ports corresponding to each other may be provided, and three or more air flow paths may be provided. In this case, the air flow path may be changed in a predetermined order.

  The above-described embodiments are merely examples, and the scope of the present invention should not be interpreted in a limited manner. The scope of the present invention is defined by the scope of the claims, and all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  Here, a test apparatus A, which is a fuel vapor processing apparatus having the same configuration as that of the first embodiment, was prepared. However, the purge pipe is not provided with a purge valve.

  In the test apparatus A, after the evaporated fuel is sufficiently adsorbed by the adsorbents in the first and second adsorption chambers, the first and second tank ports are closed, and the purge pipe is set at 20 L / min. Purging was performed. At this time, switching to the first adsorption chamber side and switching to the second adsorption chamber side by the first switching valve were alternately repeated every minute.

  For comparison, test apparatuses B and C were prepared. The test apparatus B differs from the test apparatus A only in that the first switching valve is not provided, and the first and second branch pipes branch directly from the main pipe of the purge pipe. In this test apparatus B, the purge was performed at a rate of 20 L / min from the purge pipe in the same manner as the test apparatus A. As a result, in the test apparatus B, the desorption of the evaporated fuel is continuously performed in both the first adsorption chamber and the second adsorption chamber.

  In the test apparatus C, a second purge port and a first drain port are connected, and a purge pipe (no branch pipe) is connected to the first purge port. In this test apparatus C, similarly to the test apparatuses A and B, the purge was performed at a rate of 20 L / min from the purge pipe. That is, in the test apparatus C, air is sucked from the second drain port, and the air flows in order from the first purge port through the second adsorption chamber (second path) and the first adsorption chamber (first path). leak.

  In the above test apparatuses A to C, the total purge flow rate from the start of purge ((20 L / min) × time from the start of purge) and the total desorption of the evaporated fuel adsorbed by the adsorbent in the first and second adsorption chambers. The relationship with release weight was investigated. The result is shown in FIG.

  It can be seen that the total desorbed weight of the evaporated fuel in the test apparatus A is larger than that in the test apparatus B. For example, when the total purge flow rate is 400 L, the total desorbed weight of the evaporated fuel in the test apparatus A is 7% larger than that of the test apparatus B. That is, in the test apparatus B, since the evaporative fuel is continuously desorbed in both the first and second adsorption chambers, the temperature of the adsorbent in both adsorption chambers decreases, and Total desorption weight is reduced. On the other hand, in the test apparatus A, while the evaporated fuel is desorbed in one of the first and second adsorption chambers, the evaporated fuel is desorbed in the other adsorption chamber. Since the temperature of the adsorbent in the other adsorption chamber rises and the vaporized fuel is desorbed after the temperature rises, the total desorbed weight of the vaporized fuel is equal to the test apparatus B. More than. In the test apparatus A, the switching by the first switching valve is performed every minute without considering the temperature of the adsorbent. However, as in each of the above embodiments, the first switching valve is considered in consideration of the temperature of the adsorbent. 1 is switched by the switching valve, that is, the air flow path is changed when it is determined that the amount of decrease in the temperature of the adsorbent on the path through which the air flow flows is equal to or greater than the predetermined value. Thus, it is considered that the total desorbed weight of the evaporated fuel can be maximized.

  In the test apparatus C, the evaporative fuel is continuously desorbed in both the first and second adsorption chambers, and the purge efficiency is worse than that in the test apparatus B. Is the least.

  Next, a test apparatus D was prepared in which the connection between the second purge port and the first drain port was released from the test apparatus C and only the first adsorption chamber was provided. In this test apparatus D, purging was performed at 20 L / min from the purge pipe. At this time, the outside air temperature is set to 18.6 ° C., 35.0 ° C., 40.6 ° C., and the adsorption in the vicinity of the first purge port on the first path with respect to the time from the start of the purge for each of the outside air temperatures. The temperature change of the agent was examined. The result is shown in FIG. It can be seen from FIG. 8 that the temperature of the adsorbent rapidly decreases due to the purge. It should be noted that the temperature of the adsorbent at the start of the purge at each of the above ambient temperatures is slightly higher than the ambient temperature.

  Further, the relationship between the total purge flow rate from the start of the purge and the total desorbed weight of the evaporated fuel adsorbed by the adsorbent in the first adsorption chamber was examined for each of the above outside air temperatures. The result is shown in FIG. FIG. 9 shows that the total desorbed weight of the evaporated fuel decreases as the outside air temperature decreases. This is because, as shown in FIG. 8, when the outside air temperature is low, the temperature of the adsorbent is lowered accordingly.

  INDUSTRIAL APPLICABILITY The present invention is useful for an evaporative fuel processing apparatus provided with a canister, and particularly useful when the pumping loss of an internal combustion engine is reduced and the negative pressure generated in the canister is small.

1 canister 2 adsorption chamber 2a first adsorption chamber 2b second adsorption chamber 6a first purge port 6b second purge port 7a first drain port 7b second drain port 12 purge pipe 12a main pipe 12b first branch pipe 12c second branch pipe 13 drain pipe 13a main pipe 13b first branch pipe 13c second branch pipe 18a first path 18b second path 21 first switching valve (path control means)
22 Second switching valve (route control means)
38 Temperature sensor 51 Engine controller (path control means) (switching valve control means)
(Determination means) (estimation means)

Claims (7)

Evaporative fuel having a canister that adsorbs the evaporated fuel generated in the fuel tank by an adsorbent accommodated therein, and desorbs the adsorbed evaporated fuel from the adsorbent to supply it to the intake system of the internal combustion engine. A processing device comprising:
The canister has a plurality of purge ports connected to the intake system, and a plurality of drain ports provided corresponding to the plurality of purge ports, respectively, and opening the inside of the canister to the atmosphere,
Between the purge port and the drain port corresponding to each other in the canister, a path through which an air flow flows from the drain port to the purge port via the adsorbent when the evaporated fuel is supplied to the intake system is provided. And
Path control means for controlling the air flow path so that the air flow flows along one of the plurality of paths when the evaporated fuel is supplied to the intake system;
Determining means for determining whether or not the amount of decrease in the temperature of the adsorbent on the path through which the airflow flows when the evaporated fuel is supplied to the intake system is greater than or equal to a predetermined value;
The path control means is a path through which the air flow flows when the determination means determines that the amount of decrease in the temperature of the adsorbent on the path through which the air flow flows is equal to or greater than the predetermined value. An evaporative fuel processing apparatus configured to change a path of the air flow so that the air flow flows along a path different from the above. The evaporative fuel processing apparatus of Claim 1 WHEREIN:
The canister has a plurality of adsorption chambers containing the adsorbent,
The plurality of paths are provided in the adsorption chambers different from each other,
The plurality of purge ports are connected to the intake system via a purge pipe,
The purge pipe is formed by connecting a main pipe connected to the intake system and a plurality of branch pipes respectively connected to the plurality of purge ports via a switching valve,
The switching valve can switch a communication state so that the main pipe of the purge pipe and any one of the plurality of branch pipes communicate with each other when the evaporated fuel is supplied to the intake system. Configured,
The fuel vapor processing apparatus according to claim 1, wherein the path control means includes the switching valve and switching valve control means for controlling the operation of the switching valve. The evaporative fuel processing apparatus of Claim 1 WHEREIN:
The canister has a plurality of adsorption chambers containing the adsorbent,
The plurality of paths are provided in the adsorption chambers different from each other,
Connected to the plurality of drain ports are drain pipes whose ends are open to the atmosphere,
The drain pipe is formed by connecting a main pipe on the distal end side and a plurality of branch pipes respectively connected to the plurality of drain ports via a switching valve,
The switching valve can switch a communication state so that the main pipe in the drain pipe and any one of the plurality of branch pipes communicate with each other when the evaporated fuel is supplied to the intake system. Configured,
The fuel vapor processing apparatus according to claim 1, wherein the path control means includes the switching valve and switching valve control means for controlling the operation of the switching valve. The evaporative fuel processing apparatus of Claim 1 WHEREIN:
The canister has one adsorption chamber in which the adsorbent is accommodated,
The plurality of paths are provided in the adsorption chamber,
The plurality of purge ports are connected to the intake system via a purge pipe,
The purge pipe is configured such that a main pipe connected to the intake system and a plurality of branch pipes respectively connected to the plurality of purge ports are connected via a first switching valve.
The first switching valve switches the communication state so that the main pipe in the purge pipe and any one of the plurality of branch pipes communicate with each other when the evaporated fuel is supplied to the intake system. Configured and possible
Connected to the plurality of drain ports are drain pipes whose ends are open to the atmosphere,
The drain pipe is formed by connecting a main pipe on the distal end side and a plurality of branch pipes respectively connected to the plurality of drain ports via a second switching valve,
The second switching valve switches a communication state so that the main pipe in the drain pipe and any one of the plurality of branch pipes communicate with each other when the evaporated fuel is supplied to the intake system. Configured to be possible,
The path control means includes the first and second switching valves and switching valve control means for controlling the operation of the first and second switching valves.
The evaporated fuel processing apparatus, wherein the purge port is disposed in the vicinity of a drain port not corresponding to the purge port. In the evaporative fuel processing apparatus as described in any one of Claims 1-4,
An estimation means for estimating the amount of evaporated fuel that is desorbed from the adsorbent on the path through which the airflow flows when the evaporated fuel is supplied to the intake system, and is supplied to the intake system;
The determination means determines whether or not the amount of decrease in the temperature of the adsorbent on the path through which the airflow flows is equal to or greater than the predetermined value based on the evaporated fuel amount estimated by the estimation means. An evaporative fuel processing apparatus characterized in that the evaporative fuel processing apparatus is configured. In the evaporative fuel processing apparatus as described in any one of Claims 1-4,
A temperature sensor that is disposed on one of the plurality of paths and detects the temperature of the adsorbent on the path;
When the air flow is flowing along a path where the temperature sensor is disposed, the determination means is configured to adsorb the adsorption on the path through which the air flow flows based on a detection value by the temperature sensor. While it is determined whether or not the amount of decrease in the temperature of the agent is equal to or greater than the predetermined value, if the airflow is flowing along a path where the temperature sensor is not disposed, along the path The amount of decrease in the temperature of the adsorbent after the air flow begins to flow when the air flow is flowing along the path in which the temperature sensor is disposed. The adsorbent on the path in which the airflow flows along the path where the temperature sensor is not disposed, depending on whether or not it is longer than the time until it is determined that the airflow has exceeded the predetermined value Whether or not the amount of decrease in temperature has exceeded the specified value Evaporative fuel processing apparatus characterized by being configured to determine. The evaporative fuel processing apparatus of Claim 6 WHEREIN:
The evaporated fuel processing apparatus, wherein the temperature sensor is disposed in the vicinity of a purge port on one of the plurality of paths.

Images