JP2007016622A - Evaporation gas treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaporation gas treatment device capable of reduction of purge of evaporation gas into an engine when combustion does not occur in an engine combustion chamber, and of treatment of evaporation gas. <P>SOLUTION: This device is provided with a canister 2, a purge control valve 6, a tank 10 provided between the purge control valve 6 and the intake air passage 4, a check valve 11 permitting only flow from the tank 10 to the intake air passage 4, a tank pressure measurement means, and a control means 4 controlling open and close of the purge control valve 6 when signal of fuel cut or ignition cut is received. The control means 14 shuts off flow of evaporation gas into the intake air passage 4 from the canister 2 and accumulates vacuum of the intake air passage 4 in the tank 10 by closing the purge control valve 6 when the same judges that tank pressure exceeds intake pressure, and purges evaporation gas in the canister into the tank 10 by using vacuum accumulated in the tank 10 by opening the purge control valve 6 when the same judges tank pressure is equal to or less than intake pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an evaporation gas processing apparatus that processes fuel evaporative gas (hereinafter referred to as “evaporation gas”) generated by evaporation of fuel in a fuel tank.

  In order to prevent the evaporation gas from leaking into the atmosphere, the evaporation gas is once adsorbed to the canister, and the purge control valve provided in the purge passage that connects the canister and the intake passage of the engine is opened. Thus, an evaporation gas processing device is provided for purging the evaporation gas adsorbed in the canister to the intake passage by using the negative pressure of the intake passage.

  When the engine is operating at a high load, the throttle valve is operated in a state close to full opening. In this case, almost atmospheric pressure is introduced into the intake passage and almost no negative pressure is generated, so that it is difficult to purge the evaporation gas adsorbed in the canister into the intake passage. In particular, in a hybrid vehicle, engine operation is performed in a high load state from the viewpoint of energy efficiency, and thus it is difficult to purge the evaporation gas into the intake passage.

Therefore, Patent Document 1 discloses an invention relating to a vehicle control device that opens a purge control valve and purges the evaporation gas in an operating state in which the throttle valve is closed when the load is reduced from engine high load operation.
JP 2001-98994 A

  In such a vehicle control apparatus, the evaporation gas is purged only when the throttle valve is closed when the engine load is reduced, and the evaporation gas is purged less frequently. When the throttle valve is closed when the engine load is reduced, the evaporative gas is purged, and when the fuel cut or ignition cut is performed as engine combustion control, the evaporated evaporative gas purged from the canister into the engine Cannot burn in the combustion chamber. Therefore, the evaporative gas may be released into the atmosphere as it is, or may react with the catalyst to deteriorate the catalyst.

  The present invention has been made in view of the above problems, and provides an evaporation gas processing apparatus capable of reducing the purge of the evaporation gas into the engine when not burning in the engine combustion chamber and processing the evaporation gas. The purpose is to do.

  The present invention is an evaporation gas processing apparatus including a canister that adsorbs an evaporation gas generated by evaporation of fuel in a fuel tank, and a purge control valve provided in a purge passage that communicates the canister and an intake passage of an engine. This evaporation gas processing apparatus is provided between a pressure accumulation container provided between a purge control valve and an intake passage in a purge passage, and between a pressure accumulation vessel and an intake passage in a purge passage, and only flows from the pressure accumulation vessel to the intake passage. A non-combustion state of the engine, a check valve that measures the intake pressure in the intake passage, an accumulator pressure measuring means that measures or estimates the accumulator pressure in the accumulator, and an unburned state of the engine A control means for controlling the opening and closing of the purge control valve based on the pressure accumulation container pressure and the intake pressure. The control means closes the purge control valve when the pressure accumulation container pressure exceeds the intake pressure, thereby shutting off the inflow of the evaporation gas from the canister to the intake passage, and the intake passage in the pressure accumulation container. When the negative pressure is accumulated and the accumulator pressure is less than the intake pressure, the purge control valve is opened to purge the evaporative gas in the canister into the accumulator using the negative pressure accumulated in the accumulator To do.

  According to the present invention, when combustion is not performed in the engine combustion chamber, that is, in the case of fuel cut or ignition cut, when the pressure accumulation container pressure exceeds the intake pressure, the purge control valve is closed and the evaporation gas from the canister to the intake passage is closed. Inflow is blocked. Further, when the pressure accumulation container pressure is equal to or lower than the intake pressure, the purge control valve is opened. However, since the flow of the evaporation gas from the pressure accumulation container to the intake passage does not occur, the inflow of the evaporation gas to the intake passage is similarly blocked. As described above, when the combustion is not performed in the engine combustion chamber, the purge of the evaporation gas into the engine can be reduced.

  Furthermore, when the pressure accumulation container pressure is equal to or lower than the intake pressure and the purge control valve is opened, the evaporation gas in the canister can be purged into the pressure accumulation container and processed using the negative pressure accumulated in the pressure accumulation container. . At this time, since a check valve is provided between the pressure accumulator vessel and the intake passage to allow only the flow from the pressure accumulator vessel to the intake passage, air in the intake passage does not flow into the pressure accumulator vessel. The evaporation gas in the canister can be efficiently purged into the pressure accumulating vessel.

  Furthermore, even in a situation where sufficient negative pressure does not occur in the intake passage during engine high load operation, the evaporation gas in the canister can be purged into the pressure storage container and processed by using the negative pressure stored in the pressure storage container. Can do.

  As described above, when the combustion is not performed in the engine combustion chamber, the purge of the evaporation gas into the engine can be reduced and the evaporation gas in the canister can be processed.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an evaporation gas processing apparatus 100 according to Embodiment 1 of the present invention.

(Embodiment 1)
The evaporative gas processing apparatus 100 processes evaporative gas generated by evaporation of the fuel in the fuel tank 9. The evaporative gas processing apparatus 100 has a canister 2 containing a fuel adsorbent (activated carbon), a canister 2 and a downstream of a throttle valve 3 of the engine 1. A purge control valve 6 provided in a purge passage 5 communicating with the intake passage 4 and a controller 14 mounted on the vehicle and controlling the operation of the entire vehicle and the operation of the purge control valve 6 are provided.

  The evaporation gas generated in the fuel tank 9 is guided to the canister 2 through the pipe 7, and only the fuel component is adsorbed by the activated carbon in the canister 2, and the remaining air is externally supplied from the atmosphere release valve 8 provided in the canister 2. To be released. In order to process the fuel adsorbed on the activated carbon, the purge control valve 6 is opened, and fresh air is introduced into the canister 2 from the atmosphere release valve 8 using the suction negative pressure downstream of the throttle valve 3. The fuel adsorbed on the activated carbon is released by the fresh air, and is introduced into the engine 1 from the intake passage 4 through the purge passage 5 together with the fresh air.

  The evaporative gas purge operation in the evaporative gas processing apparatus 100 described above is performed when fuel cut or ignition cut is not performed as combustion control of the engine 1, that is, when combustion is performed in the engine combustion chamber. is there. However, when fuel cut or ignition cut is performed as combustion control of the engine 1, that is, when the above-described normal purge operation is performed when combustion is not performed in the engine combustion chamber, the inside of the engine 1 from the canister 2 is performed. The evaporative gas flowing into the engine cannot be combusted in the engine combustion chamber and is released into the atmosphere.

  Therefore, the evaporation gas processing apparatus 100 has the following configuration for reducing the purge of the evaporation gas into the engine 1 when not burning in the engine combustion chamber.

  The evaporation gas processing apparatus 100 is provided between the purge control valve 6 in the purge passage 5 and the intake passage 4 as a pressure accumulation container, and between the tank 10 in the purge passage 5 and the intake passage 4. A check valve 11, an intake pressure gauge 12 as an intake pressure measuring means for measuring the intake pressure in the intake passage 4, and a tank pressure measuring means for measuring or estimating the tank pressure in the tank 10 are provided.

  The purge control valve 6 is an electromagnetic on-off valve that is controlled by a controller 14 to be described later. When combustion is not performed in the engine combustion chamber, the purge control valve 6 is opened / closed by comparing the tank pressure with the intake pressure, and the evaporative gas canister 2 is operated. To flow into the engine 1.

  The tank 10 is a container having a constant volume, and accumulates the negative pressure in the intake passage 4 by opening and closing the purge control valve 6 when the combustion is not performed in the engine combustion chamber, and uses the accumulated negative pressure. Thus, it has a function of receiving the evaporation gas in the canister 2. Specifically, when the tank pressure exceeds the intake pressure, the purge control valve 6 is closed and the tank 10 accumulates the negative pressure in the intake passage 4. When the tank pressure is equal to or lower than the intake pressure, the purge control valve 6 is opened, and the tank 10 sucks the evaporation gas in the canister 2. That is, the evaporation gas in the canister 2 is purged to the tank 10.

  The check valve 11 allows only the flow of the evaporation gas from the tank 10 to the intake passage 4, and prevents the air in the intake passage 4 from flowing into the tank 10. Therefore, when the tank pressure exceeds the intake pressure and the purge control valve 6 is closed, a flow from the tank 10 to the intake passage 4 occurs, but no flow from the intake passage 4 to the tank 10 occurs. 10, the negative pressure in the intake passage 4 is efficiently accumulated. Further, when the tank pressure becomes equal to or lower than the intake pressure and the purge control valve 6 is opened, the air in the intake passage 4 does not flow into the tank 10 due to the action of the check valve 11. Evaporative gas can be efficiently purged into the tank 10.

  The intake pressure gauge 12 is attached downstream of the throttle valve 3 in the intake passage 4 and directly measures the pressure in the intake passage, and outputs the measured intake pressure data to the controller 14.

The tank pressure measuring means obtains the current estimated tank pressure value from the measured pressure in the vicinity of the tank 10 using a first-order lag function (a) shown below stored in the controller 14.
Tank pressure (n) = A × measured pressure (n) + (1−A) × tank pressure (n−1) (a)

  Thus, the current pressure in the tank 10 is indirectly measured using the measured pressure in the vicinity of the tank 10 and the previous estimated value of the tank pressure. Here, when the purge control valve 6 is open, the measured pressure is the pressure measured by the atmospheric pressure gauge 17 as the atmospheric pressure measuring means for measuring the atmospheric pressure, and the purge control valve 6 is closed. For this, the intake pressure measured by the intake pressure gauge 12 is used. A is a weighting factor, and by arbitrarily setting the value of A, the weighting of the measured pressure (n) and the tank pressure (n-1) can be freely set.

  As another method for measuring the pressure in the tank 10, a tank pressure gauge may be attached to the tank 10, the pressure in the tank 10 may be directly measured, and the tank pressure data may be output to the controller 14.

  The controller 14 includes a CPU, a ROM, a RAM (not shown), and the like. Based on the operating conditions of the engine 1 detected by various instruments, the controller 14 determines the ignition timing of the engine 1, the fuel injection amount, and the opening and closing of the purge control valve 6. Take control.

  Next, operation | movement of the evaporation gas processing apparatus 100 by the controller 14 is demonstrated with reference to FIG. FIG. 2 is a flowchart showing the operation of the evaporation gas processing apparatus 100, which is executed at a constant cycle.

  The intake pressure is read by the intake pressure gauge 12 (step 1-1).

  The pressure is read by the atmospheric pressure gauge 17 or the intake pressure gauge 12, and the tank pressure is estimated using the first-order lag function (a) stored in the controller 14 (step 1-2). Note that when the purge control valve 6 is open, the atmospheric pressure measured by the atmospheric pressure gauge 17 is used, and when the purge control valve 6 is closed, the intake pressure measured by the intake pressure gauge 12 is used to set the tank pressure. Is calculated. The tank pressure may be measured by attaching a pressure gauge to the tank 10 and directly measuring and reading the tank pressure.

  It is determined whether an ignition cut signal is output from the controller 14 to the spark plug 15 or a fuel cut signal is output to the fuel injection valve 16 (step 2). That is, it is determined whether or not the engine combustion chamber is in an unburned state.

  In step 2, when the ignition cut signal to the spark plug 15 or the fuel cut signal to the fuel injection valve 16 is not output, that is, when the combustion state of the engine is detected, the engine speed, the intake air amount Based on the intake air temperature, the throttle opening, the coolant temperature, the vehicle speed, the fuel temperature, the fuel injection amount, etc., the normal purge control that opens the purge control valve 6 in a predetermined operating range (such as during steady running) is performed. Performed (step 3).

  In step 2, when the ignition cut signal to the spark plug 15 or the fuel cut signal to the fuel injection valve 16 is output, that is, when the unburned state of the engine is detected, the routine proceeds to step 4 where In other words, control different from the purge control is performed, that is, control for reducing the purge of the evaporation gas into the engine 1 is executed.

  The tank pressure measured in step 1-2 is compared with the intake pressure read in step 1-1, and it is determined whether or not the tank pressure exceeds the intake pressure (step 4). The control in Step 4 corresponds to a control means for controlling the opening / closing of the purge control valve based on the pressure accumulation container pressure and the intake pressure when an unburned state of the engine is detected.

  If it is determined in step 4 that the tank pressure exceeds the intake pressure, the purge control valve 6 is closed (step 5). Thereby, the inflow of the evaporative gas from the canister 2 to the intake passage 4 is blocked, and the inflow of the evaporative gas into the engine 1 that is not combusting is prevented. Further, since the intake pressure is lower than the tank pressure, the gas in the tank 10 is sucked by the negative pressure in the intake passage 4, and the negative pressure in the intake passage 4 is accumulated in the tank 10.

  If it is determined in step 4 that the tank pressure is equal to or lower than the intake pressure, the purge control valve 6 is opened (step 6). Even if the purge control valve 6 is opened, the tank pressure is equal to or lower than the intake pressure, so that no evaporative gas flows from the tank 10 to the intake passage 4 and the inflow of the evaporative gas into the uncombusted engine 1 is prevented. Is done. Further, since the canister 2 and the tank 10 are in communication with each other, the evaporation gas in the canister 2 is purged into the tank 10 by the negative pressure accumulated in the tank 10. At this time, since the check valve 11 is provided between the tank 10 and the intake passage 4, the air in the intake passage 4 does not flow into the tank 10 even when the tank pressure is equal to or lower than the intake pressure. The evaporation gas in the canister 2 can be efficiently purged into the tank 10. Thus, by using the negative pressure accumulated in the tank 10, the evaporated gas in the canister 2 can be processed.

  As described above, the evaporation gas processing apparatus 100 according to Embodiment 1 compares the tank pressure with the intake pressure when the tank 10, the check valve 11, and the engine combustion chamber are not combusting, and the purge control valve 6. Control means for controlling the opening and closing of the. When it is determined that the tank pressure exceeds the intake pressure, the control means closes the purge control valve 6 to shut off the inflow of the evaporation gas from the canister 2 to the intake passage 4 and The negative pressure in the intake passage 4 is accumulated. Further, the control means opens the purge control valve 6 when it is determined that the tank pressure is equal to or lower than the intake pressure, thereby utilizing the negative pressure accumulated in the tank 10 for the evaporation gas in the canister 2. Purge in. Thus, according to the evaporation gas processing apparatus 100, when the combustion is not performed in the engine combustion chamber, the purge of the evaporation gas into the engine 1 can be reduced, and the emission of the evaporation gas to the atmosphere can be prevented. . Even in such a state, the evaporation gas in the canister 2 can be purged into the tank 10 and processed by using the negative pressure accumulated in the tank 10.

  Further, in a situation where normal purge control during engine combustion is performed, when the engine 1 is operating at a high load, the throttle valve 3 is operated in a state close to full open. In this case, since almost atmospheric pressure is introduced into the intake passage 4 and almost no negative pressure is generated, it is difficult to purge the evaporative gas into the intake passage 4. In particular, in a hybrid vehicle, the engine operation is in a high load state. Since it is operated, purging becomes difficult. However, even in a situation where a sufficient negative pressure is not generated in the intake passage 4, the evaporation gas in the canister 2 can be purged and processed in the tank 10 by using the negative pressure accumulated in the tank 10. And the purge frequency can be improved.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described with reference to the flowchart of FIG. The configuration of the evaporation gas processing apparatus 200 in the second embodiment is the same as that in the first embodiment. The operation of the evaporation gas processing apparatus 200 by the controller 14 in the second embodiment is partially different from the operation in the first embodiment. The differences will be described below.

  The operations up to step 6 are the same as those in the first embodiment. After the purge control valve 6 is opened in step 6, the tank pressure is compared with the atmospheric pressure to determine whether the tank pressure is equal to or higher than the atmospheric pressure (step 7).

  If it is determined in step 7 that the tank pressure is less than the atmospheric pressure, the purge control valve 6 remains open. When it is determined that the tank pressure is equal to or higher than the atmospheric pressure, the purge control valve is closed and the flow path between the tank 10 and the canister 2 is shut off (step 8).

  As described above, according to the evaporation gas processing apparatus 200 according to the second embodiment, it is possible to prevent the evaporation gas from flowing backward from the tank 10 to the canister 2 even when the tank pressure temporarily exceeds the atmospheric pressure. it can.

(Embodiment 3)
Next, Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 4 is a configuration diagram of the evaporation gas processing apparatus 300 according to Embodiment 3 of the present invention, and FIG. 5 is a flowchart showing the operation of the evaporation gas processing apparatus 300.

  The difference between the evaporation gas processing apparatus 300 of the third embodiment and the evaporation gas processing apparatus 100 of the first embodiment is that a purge cutoff valve 20 is provided between the check valve 11 and the intake passage 4 in the purge passage 5. Is a point.

  The purge shut-off valve 20 is an electromagnetic on-off valve that opens and closes by comparing the tank pressure with the intake pressure when not burning in the engine combustion chamber.

  The operation of the purge cutoff valve 20 will be described with reference to FIG. The operations from step 1-1 to step 4 are the same as those in the first embodiment. If it is determined in step 4 that the tank pressure exceeds the intake pressure, the purge control valve 6 is closed and the purge cutoff valve 20 is opened (step 5). Thereby, the inflow of the evaporative gas from the canister 2 to the intake passage 4 is blocked, and the inflow of the evaporative gas into the engine 1 that is not combusting is prevented. Further, since the intake pressure is lower than the tank pressure, the gas in the tank 10 is sucked by the negative pressure in the intake passage 4, and the negative pressure in the intake passage 4 is accumulated in the tank 10.

  If it is determined in step 4 that the tank pressure is equal to or lower than the intake pressure, the purge control valve 6 is opened and the purge cutoff valve 20 is closed (step 6). Thereby, the evaporation gas in the canister 2 can be efficiently purged into the tank 10 and the purge cutoff valve 20 is closed, so that the evaporation of the evaporation gas purged into the tank 10 is prevented from being diffused into the engine 1. be able to.

  As described above, according to the evaporation gas processing apparatus 300 according to the third embodiment, since the purge cutoff valve 20 is provided, the purge of the evaporation gas into the engine 1 is further reduced when the combustion is not performed in the engine combustion chamber. It is possible to prevent the emission of evaporative gas to the atmosphere. Further, the evaporation gas in the canister 2 can be purged into the tank 10 more efficiently.

  In the third embodiment, steps 7 and 8 in the second embodiment may be added after the step 6 to prevent the backflow of the evaporation gas from the tank 10 to the canister 2.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described with reference to the flowchart of FIG. The configuration of the evaporation gas processing apparatus 400 in the fourth embodiment is the same as that in the third embodiment. The operation of the evaporation gas processing apparatus 400 by the controller 14 in the fourth embodiment is partially different from the operation in the third embodiment. The differences will be described below.

  The operation of the evaporation gas processing apparatus 400 includes a step 0 for determining whether or not there is an evaporative diagnosis request before the step 1-1 for reading the intake pressure. When there is an evaporative diagnosis request, the known evaporative diagnosis control is performed prior to the evaporative gas purge control (step 0-1). Further, when there is no evaporative diagnosis request, any of the evaporative gas purge control described in the first to third embodiments is performed.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  INDUSTRIAL APPLICABILITY The present invention can be used in an apparatus that is mounted on a vehicle and processes fuel evaporative gas generated by evaporating fuel in a fuel tank.

It is a block diagram of the evaporation gas processing apparatus 100 which concerns on Embodiment 1 of this invention. 3 is a flowchart showing the operation of the evaporation gas processing apparatus 100. It is a flowchart which shows operation | movement of the evaporation gas processing apparatus 200 which concerns on Embodiment 2 of this invention. It is a block diagram of the evaporation gas processing apparatus 300 which concerns on Embodiment 3 of this invention. 3 is a flowchart showing the operation of the evaporation gas processing apparatus 300. It is a flowchart which shows operation | movement of the evaporation gas processing apparatus 400 which concerns on Embodiment 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,300 Evaporative gas processing apparatus 1 Engine 2 Canister 3 Throttle valve 4 Intake passage 5 Purge passage 6 Purge valve 7 Pipe 8 Atmospheric release valve 9 Fuel tank 10 Tank 11 Check valve 12 Intake pressure gauge 14 Controller 15 Spark plug 16 Fuel injection valve 17 Atmospheric pressure gauge 20 Purge shut-off valve

Claims (5)

A canister that adsorbs evaporative gas generated by evaporation of fuel in the fuel tank;
In an evaporation gas processing apparatus comprising a purge control valve provided in a purge passage communicating the canister and an intake passage of the engine,
A pressure accumulating vessel provided between the purge control valve and the intake passage in the purge passage;
A check valve provided between the pressure accumulator vessel and the intake passage in the purge passage and allowing only a flow from the pressure accumulator vessel to the intake passage;
Intake pressure measuring means for measuring the intake pressure in the intake passage;
An accumulator pressure measuring means for measuring or estimating an accumulator pressure in the accumulator container;
Control means for controlling opening and closing of the purge control valve based on the pressure accumulation container pressure and the intake pressure when an unburned state of the engine is detected;
The control means closes the purge control valve when the pressure accumulating vessel pressure exceeds the intake pressure, thereby blocking the flow of the evaporation gas from the canister to the intake passage, and the inside of the pressure accumulating vessel To accumulate the negative pressure in the intake passage,
When the pressure-accumulation vessel pressure is equal to or lower than the intake pressure, the purge control valve is opened to purge the evaporation gas in the canister into the pressure-accumulation vessel using the negative pressure accumulated in the pressure-accumulation vessel. An evaporative gas processing apparatus. A purge cutoff valve provided between the check valve and the intake passage in the purge passage;
The control means closes the purge control valve and opens the purge shut-off valve when the pressure accumulation container pressure exceeds the intake pressure,
2. The evaporation gas processing apparatus according to claim 1, wherein when the pressure accumulation container pressure is equal to or lower than the intake pressure, the purge control valve is opened and the purge cutoff valve is closed.   3. The control unit according to claim 1, wherein the control unit closes the purge control valve when the purge control valve is opened and the pressure accumulation container pressure is equal to or higher than atmospheric pressure. The evaporation gas processing apparatus as described. Equipped with atmospheric pressure measuring means for measuring atmospheric pressure,
The evaporative gas processing apparatus according to any one of claims 1 to 3, wherein the accumulator pressure measuring means estimates the accumulator pressure by a first-order lag function of the intake pressure or the atmospheric pressure. The first-order lag function is expressed by the following equation with a weighting factor A, and the measured pressure in the equation uses the intake pressure when the purge control valve is closed, and when the purge control valve is open. 5. The evaporation gas processing apparatus according to claim 4, wherein the atmospheric pressure is used.
Current pressure accumulator pressure (n) = A × measured pressure (n) + (1−A) × pressure accumulator pressure (n−1)

Images