JP2016089761A - Evaporation fuel processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaporation fuel processing device for adsorbing evaporation fuel generated in a fuel tank to a canister, supplying the adsorbed evaporation fuel to an engine to purge it, in which a concentration of the evaporation fuel adsorbed in the canister is calculated on the basis of a value of load of a pump flowing the evaporation fuel from the canister to detect concentration of the evaporation fuel adsorbed in the canister, without providing a new concentration sensor, and simplify a configuration of the evaporation fuel processing device.SOLUTION: This invention comprises: a circulation passage connected to a canister 11 to cause evaporation fuel to flow from the canister 11 in independent from a purge passage 16; a purge pump 13A arranged in the circulation passage to cause evaporation fuel from the canister 11 to flow; and concentration estimating means for detecting a value of operating load of the purge pump 13A and estimating a concentration of the evaporation fuel adsorbed in the canister 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an evaporative fuel processing apparatus that adsorbs evaporative fuel generated in a fuel tank to a canister and supplies the adsorbed evaporative fuel to an engine via a purge passage for purging.

  In the evaporative fuel processing apparatus, it is necessary to detect the concentration of the evaporative fuel adsorbed by the canister in order to perform the purge appropriately. Therefore, in order to detect the concentration of the evaporated fuel adsorbed on the canister, the concentration of the evaporated fuel flowing into the engine during the purge is generally detected by a sensor. However, it is not preferable to detect the concentration of the evaporated fuel during the purge. This is because purging is performed for concentration detection even when purging is not originally required.

  Therefore, it is considered to connect the evaporated fuel concentration detection means to the canister through a passage independent of the purge passage, and to detect the concentration of the evaporated fuel adsorbed by the canister by flowing the evaporated fuel from the canister to the detection means. (See Patent Document 1 below).

JP 2006-161895 A

  However, the evaporative fuel concentration detection means in the passage independent of the purge passage requires a new concentration sensor, and there is a problem that the configuration of the evaporative fuel processing apparatus becomes complicated.

  In view of such problems, an object of the present invention is to provide an evaporative fuel processing apparatus that adsorbs evaporated fuel generated in a fuel tank to a canister and supplies and purges the adsorbed evaporated fuel to the engine to purge the evaporated fuel adsorbed to the canister. By determining the fuel concentration based on the load of the pump that flows the evaporated fuel from the canister, the concentration of the evaporated fuel adsorbed on the canister is detected without providing a new concentration sensor. It is to simplify the configuration.

  According to a first aspect of the present invention, there is provided an evaporative fuel processing apparatus that adsorbs evaporated fuel generated in a fuel tank to a canister via a vapor passage and supplies the adsorbed evaporated fuel to an engine via a purge passage for purging. A circulation path connected to the canister so that the evaporated fuel flows independently from the purge passage from the canister; a circulation pump provided in the circulation path for allowing the evaporated fuel from the canister to flow through the circulation path; and the circulation Concentration estimation means for detecting the magnitude of the operating load of the pump and estimating the concentration of the evaporated fuel adsorbed by the canister.

  In the first invention, the present invention may be applied to a system that does not include a purge pump in the purge passage. The magnitude of the operating load of the circulating pump can be detected by detecting the amount of operating energy of the pump, detecting the driving shaft torque of the pump, detecting the distortion caused by the load change of the pump operating unit, or the like. .

  According to a second aspect of the present invention, there is provided the purge pump according to the first aspect, further comprising a purge pump for generating an air flow for purging the purge passage, and bypassing in parallel with a part of the purge passage including the canister and the purge pump. A passage is connected, a part of the purge passage and the bypass passage serve as the circulation passage, and the purge pump also serves as the circulation pump.

  In a third aspect of the present invention based on the second aspect, a purge valve is provided in a portion of the purge passage where the purge pump is connected to the engine.

  According to a fourth aspect of the present invention, in the second or third aspect of the invention, the purge pump is a reversible pump capable of arbitrarily reversing a discharge port and a suction port as a pump, and the bypass passage includes An on-off valve for preventing the flow from the purge pump to the canister is inserted.

  In the fourth invention, the on-off valve may be a check valve, an electromagnetic on-off valve or the like.

  According to a fifth aspect of the present invention, there is provided the purge pump according to the first aspect, further comprising a purge pump for generating an air flow for causing the purge passage to perform a purge, wherein the purge passage is purged at a portion connecting the purge pump to the canister. A purge valve that opens the purge valve when purging by the purge pump, and closes the purge valve when the concentration of the evaporated fuel is estimated by the circulation pump.

  In the fifth invention, the purge pump and the circulation pump may be configured independently of each other, or may be configured to be driven by one motor.

  In a sixth aspect of the present invention based on the fifth aspect, the circulation pump and the purge pump are driven by a single motor.

  According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the circulation pump and the purge pump are rotary pumps and have a common rotating shaft.

  According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the circulating pump is driven by a motor, and the magnitude of the load is at least one of a current flowing through the motor or a rotational speed of the motor. Detected by.

  According to a ninth aspect of the present invention, there is provided the purge pump control means for controlling the purge pump according to the evaporated fuel concentration of the canister estimated by the concentration estimation means in any of the second to eighth aspects.

  According to the present invention, the detection of the concentration of the evaporated fuel adsorbed by the canister is detected based on the load of the circulation pump for flowing the evaporated fuel from the canister to the circulation path, thereby providing no new concentration sensor. The concentration of the evaporated fuel adsorbed by the canister can be detected, and the configuration of the evaporated fuel processing device can be simplified. Further, when the purge pump provided in the purge passage also serves as the circulation pump, it is not necessary to provide a dedicated circulation pump, and the configuration can be further simplified.

It is a system configuration figure in a 1st embodiment of the present invention. It is a block diagram of the control circuit in a 1st embodiment. 6 is a flowchart of a purge concentration estimation processing routine in the first embodiment. It is a flowchart of the purge control processing routine in 1st Embodiment. It is a graph explaining the detection of the magnitude | size of the pump load in 1st Embodiment. It is a system configuration figure in a 2nd embodiment of the present invention. It is a system configuration figure in a 3rd embodiment of the present invention. It is explanatory drawing explaining an example of a structure of the purge pump in 3rd Embodiment. It is explanatory drawing explaining another example of a structure of the purge pump in 3rd Embodiment.

<First embodiment>
1 to 4 show a first embodiment of the present invention. This embodiment is an evaporated fuel processing apparatus added to an engine system of a vehicle.

  As shown in FIG. 1, the canister 11 in the evaporated fuel processing apparatus 10 is connected to a space portion of the fuel tank 1 through a vapor passage 15 connected to the vapor port 11a, and the fuel vapor (evaporated in the fuel tank 1 during refueling) Hereinafter, the evaporated fuel or vapor) is adsorbed to the canister 11 via the vapor passage 15. On the other hand, the canister 11 is connected to an air supply passage (not shown) of the engine 2 via a purge passage 16 connected to the purge port 11b. In the purge passage 16, a purge pump 13A and a purge valve 12 are connected in series. Has been inserted. The purge pump 13 </ b> A and the purge valve 12 are controlled by a control circuit 21 described later to open the purge passage 16 to generate an air flow in the purge passage 16 and promote the purge of the canister 11. Therefore, the evaporated fuel adsorbed by the canister 11 when refueling the fuel tank 1 is supplied to the engine air supply passage via the purge passage 16 and purged. Further, the canister 11 is provided with an atmospheric port 11c, and the atmospheric air is introduced into the atmospheric port 11c through an air filter 14. Therefore, when adsorbing the evaporated fuel in the fuel tank 1 to the canister 11, the air after adsorbing the evaporated fuel is released into the atmosphere through the air filter 14 and the adsorbed evaporated fuel is purged. The air is taken into the canister 11 through the air filter 14.

  A bypass passage 17 is connected in parallel to a portion of the purge passage 16 including the canister 11 and the purge pump 13A. Specifically, the bypass passage 17 has one end connected to a circulation port 11d provided at a position facing the purge port 11b in the canister 11, and the other end connected to the discharge port of the purge pump 13A. Therefore, when the purge pump 13A is operated, a purge flow indicated by a solid line A flowing along the purge passage 16 and a circulation flow indicated by a broken line B flowing along a part of the bypass passage 17 and the purge passage 16 are formed. The If the purge valve 12 is open at that time, the purge flow indicated by the solid line A flows through the purge valve 12, and therefore the circulation flow indicated by the broken line B hardly flows. On the other hand, if the purge valve 12 is closed, the purge flow indicated by the solid line A does not flow, so that only the circulation flow indicated by the broken line B flows. The circulating flow is used to estimate the concentration of the evaporated fuel adsorbed by the canister 11 based on the load of the purge pump 13A that generates the circulating flow, as will be described in detail later.

  FIG. 2 shows a control circuit 21 of the engine system including the evaporated fuel processing device 10. Here, illustration of portions not directly related to the present invention is omitted. The basic configuration of the engine control circuit 21 is a well-known one that controls the operation of the entire engine system, and performs valve opening control, ignition timing control, etc. of the engine fuel injection valve (not shown), and operation control of the purge pump 13A. In addition, valve opening control of the purge valve 12 is also performed. Therefore, as is well known, the engine control circuit 21 is connected to the throttle valve opening amount sensor 3, the air supply pipe pressure sensor 4, the air-fuel ratio sensor 5, etc., and receives detection signals from each of them.

  FIG. 3 shows a purge concentration estimation processing routine characteristic of the present invention, which is performed by a computer in the engine control circuit 21. When the processing of this routine is executed, it is determined in step S1 whether or not the engine 2 is being driven. If the engine 2 is driven and step S1 is affirmed, it is determined in step S2 whether or not purge is permitted. In an air-fuel ratio control routine (not shown), if air-fuel ratio feedback control is not executed and purge is not permitted, a negative determination is made in step S2, and the purge valve 12 is closed in step S3. In the next step S4, the purge pump 13A is operated. Therefore, the circulation flow shown by the broken line B in FIG. 1 is generated by opening the purge valve 12 and operating the purge pump 13A.

  In step S5, it is determined whether or not a predetermined time has elapsed. When the predetermined time has elapsed, an affirmative determination is made in step S5, and in step S6, the operating current of the motor (not shown) that drives the purge pump 13A or the rotational speed of the motor. It is determined whether or not has reached a stable state. If the operating current or the rotational speed of the motor becomes stable and step S6 is affirmed, it is determined in step S7 whether or not the motor operating current is greater than or equal to a predetermined value or the rotational speed is less than or equal to a predetermined value. If the motor operating current is greater than or equal to a predetermined value or the rotational speed is less than or equal to a predetermined value and a positive determination is made in step S7, the vapor concentration is calculated in step S8.

  FIG. 5 shows the rotational speed and current characteristics with respect to the load (torque) of the motor that drives the purge pump 13A. The load of the purge pump 13A varies depending on the concentration of evaporated fuel in the air flowing as a circulating flow, and the load increases as the evaporated fuel concentration increases. Therefore, in the characteristics shown in FIG. 5, if the load in a state where the concentration of the evaporated fuel is zero and the circulating flow is only air is T1, the rotational speed of the motor at that time is N1, and the current is I1. On the other hand, when the concentration of the evaporated fuel in the circulating flow is a predetermined high concentration, the load is T2 larger than T1, the motor rotation speed is N2 smaller than N1, and the current is I2 larger than I1. Thus, the concentration of the evaporated fuel can be calculated by detecting the change in the rotation speed or current of the motor. When the calculation of the vapor concentration is completed in this way, the purge permission flag is set in step S9 and the purge is permitted.

  When the purge concentration estimation processing routine is executed, the engine is not driven in step S1, and a negative determination is made in step S1, or purge is permitted and purge is performed in step S2, and step S2 is positive In step S7, the load of the purge pump 13A is abnormally small due to an air leak in any of the bypass passage 17 and the purge passage 16 forming the circulation path in step S7, and the operating current of the motor is a predetermined value. If the number of revolutions is not less than the predetermined value or a negative determination is made in step S7, each step of the purge concentration estimation processing routine is skipped and the processing of this routine ends.

  FIG. 4 shows a purge control processing routine characteristic of the present invention, which is performed by a computer in the engine control circuit 21. When the processing of this routine is executed, it is determined in step S11 whether or not purge is permitted. If air-fuel ratio feedback control is executed in an air-fuel ratio control routine (not shown) of the engine, and the purge permission flag is set and purge is permitted in the purge concentration estimation processing routine as described above, step S11 is positively determined. In step S12, the target purge amount is calculated based on the vapor concentration calculated in step S8 of FIG. Here, when the calculated vapor concentration is relatively high, the target purge amount is increased to purge the evaporated fuel adsorbed on the canister 11 at an early stage. When the calculated vapor concentration is relatively low, The target purge amount is reduced.

  In step S13, the purge valve 12 is opened, and in step S14, the purge pump 13A is controlled based on the target purge amount. Therefore, the canister 11 is purged by the purge flow indicated by the solid line A in FIG. 1, and the discharge flow rate of the purge pump 13A at that time is controlled in proportion to the target purge amount.

  If purging is not permitted in step S11 and a negative determination is made in step S11, the processing after step S12 is skipped, the purge pump 13A is stopped in step S15, and the purge valve 12 is closed in step S16. . As a result, the purge by the purge passage 15 is stopped.

  According to the first embodiment, a bypass passage 17 independent of the purge passage 16 is connected to the canister 11, and a circulation flow independent of the purge flow is caused to flow through the bypass passage 17 by the purge pump 13 </ b> A. The concentration of evaporated fuel adsorbed on the fuel is estimated. Therefore, it is not necessary to perform a purge for detecting the vapor concentration of the canister 11, and the adverse effect on the air-fuel ratio of the engine for detecting the vapor concentration can be suppressed. Further, the vapor concentration detection is performed based on the load of the purge pump 13A as a circulation pump for flowing the evaporated fuel from the canister 11 to a part of the bypass passage 17 and the purge passage 16. Therefore, the vapor concentration detection can be performed without providing a new concentration sensor, and the configuration of the evaporated fuel processing apparatus can be simplified. Moreover, since the purge pump 13A provided in the purge passage 16 also serves as a circulation pump, it is not necessary to provide a dedicated circulation pump, and the configuration can be further simplified.

  In addition, since the purge flow rate is controlled by controlling the purge pump 13A based on the calculated vapor concentration, the canister 11 can be purged without excess or deficiency. Therefore, the canister 11 can be purged to a state where the evaporated fuel generated at the time of refueling can be adsorbed, and the purge pump 13A is operated only when necessary, so that useless energy consumption can be avoided and fuel consumption can be improved. .

  In the first embodiment, the processing of step S1 to step S8 corresponds to the concentration estimation means of the present invention, and the processing of step S11 to step S16 corresponds to the purge pump control means of the present invention.

<Second Embodiment>
FIG. 6 shows a second embodiment of the present invention. The feature of the second embodiment over the first embodiment is that the purge pump 13A in the first embodiment is changed to a reversible pump that can arbitrarily reverse the discharge port and the suction port as a pump. Is a point. The other points are the same, and the repetitive description of the same part is omitted.

  In FIG. 6, when the purge pump 13 </ b> B is a reversible pump and the circulating flow indicated by the broken line B is caused to flow along a part of the bypass passage 17 and the purge passage 16, the purge indicated by the solid line A along the purge passage 16. The rotation of the purge pump 13B is reversed with respect to the flow. As a result, the circulating flow indicated by the broken line B is a flow in the opposite direction to the first embodiment in the second embodiment. Therefore, a check valve (corresponding to the on-off valve of the present invention) 18 is provided in the bypass passage 17, and only the circulation flow indicated by the broken line B flows in the bypass passage 17, and the purge of the solid line A that is the opposite flow. The flow is prevented from flowing.

  According to the second embodiment, when the vapor concentration is detected, the purge pump 13B is reversed and the circulation flow indicated by the broken line B is allowed to flow. In this way, the circulation flow when performing vapor concentration detection is opposite to the purge flow indicated by the solid line A when performing purge in the purge pump 13B, so that the purge flow does not flow into the bypass passage 17. And energy loss of the purge pump 13B can be suppressed.

<Third embodiment>
FIG. 7 shows a third embodiment of the present invention. The feature of the third embodiment over the first embodiment is that the purge pump 13A in the first embodiment is a multi-port pump having two pairs of discharge ports and suction ports as pumps. is there. Along with this, a circulation path through which a circulation flow indicated by a broken line B flows is constituted only by the bypass passage 17, and the canister 11 is provided with a pair of circulation ports 11 d and 11 e as connection ports to the bypass passage 17. The position of the purge valve 12 in the purge passage 16 is a portion where the purge pump 13C is connected to the canister 11. The other points are the same, and the repetitive description of the same part is omitted.

  FIG. 8 shows an example of the structure of a purge pump 13C that is a multi-port pump. The purge pump 13C is configured such that one rotary blade 132b of the pump unit 132 is rotationally driven by the motor unit 131 via the drive shaft 132a. A combination of a circulation suction port 132c and a circulation discharge port 132d, and a combination of a purge suction port 132e and a purge discharge port 132f are provided on the side closer to the rotation center of the rotary blade 132b and the side far from the rotation center. Therefore, when the rotary blade 132b is rotated, air is sucked from the circulation suction port 132c and discharged to the circulation discharge port 132d. At the same time, air is sucked from the purge suction port 132e, and the air is discharged to the purge discharge port 132f. It functions to discharge.

  As shown in FIG. 7, when detecting the vapor concentration, the purge pump 13C is operated with the purge valve 12 closed. The purge pump 13C sucks air from the circulation suction port 132c, discharges air to the circulation discharge port 132d, and generates a circulation flow indicated by a broken line B in the bypass passage 17. Therefore, the evaporated fuel adsorbed by the canister 11 is sucked out from the circulation port 11e and flows as a circulation flow. At this time, since the purge valve 12 is closed, the purge flow indicated by the solid line A does not flow. Therefore, the current or rotation speed of the motor unit 131 of the purge pump 13C becomes a value corresponding to the concentration of the evaporated fuel contained in the circulating flow, and the vapor concentration can be estimated based on the current or rotation speed of the motor unit 131.

  When purging after detecting the vapor concentration, the purge pump 13C is operated with the purge valve 12 open. The purge pump 13C sucks air from the purge suction port 132e, discharges air to the purge discharge port 132f, and generates a purge flow indicated by a solid line A in the purge passage 16. Therefore, the evaporated fuel adsorbed on the canister 11 can be purged. At this time, the purge pump 13C generates a circulation flow indicated by a broken line B in the bypass passage 17, but the evaporated fuel adsorbed by the canister 11 is purged by the purge passage 16, and therefore hardly flows in the circulation flow. Therefore, the load of the purge pump 13C is small, and the energy accompanying the circulation flow of the purge pump 13C is not so great. Moreover, if the flow rate of the circulation flow generated through the circulation suction port 132c and the circulation discharge port 132d is set to be small, the energy associated with the purge pump 13C flowing the circulation flow can be further reduced.

  In the third embodiment, since the purge valve 12 is arranged on the canister 11 side from the purge pump 13C, there is a merit that the canister 11 side always has a negative pressure from the purge valve 12. When the purge valve 12 is arranged on the engine 2 side from the purge pump 13A as in the first embodiment, the purge valve 12 side has a positive pressure, and when the purge valve 12 is closed, the positive pressure air is on the canister 11 side. There is a possibility of backflow. In the arrangement of the purge valve 12 of the third embodiment, the backflow can be suppressed.

  FIG. 9 shows another example of the structure of a purge pump 13C that is a multi-port pump. The purge pump 13C of FIG. 8 has one rotary blade 132b, whereas the purge pump 13C of FIG. 9 is arranged in the pump unit 134 so as to overlap one drive shaft 134a of the motor unit 133. It is characterized by having two rotating blades 134b and 134c. The two rotary blades 134b and 134c are configured to be driven to rotate simultaneously. The circulation suction port 134d and the circulation discharge port 134e are provided on the rotary blade 134b, and the purge suction port 134f and the purge discharge port 134g are provided on the rotary blade 134c.

  As the evaporated fuel processing apparatus 10 of the third embodiment, even when the purge pump 13C of FIG. 9 is applied, it functions in the same manner as when the purge pump 13C of FIG. 8 is applied.

  As mentioned above, although specific embodiment was described, this invention is not limited to those external appearances and structures, A various change, addition, and deletion are possible in the range which does not change the summary of this invention. For example, in the above embodiment, the canister is purged only when the purge pump is operated. However, the purge is performed while the canister vapor concentration is high, and the purge is performed after the vapor concentration is low. The operation of the pump may be stopped, and the purge may be performed using the negative pressure of the engine air supply pipe. Moreover, in the said embodiment, although this invention was applied to the engine system for vehicles, this invention is not limited to vehicles. In the case of an engine system for a vehicle, a hybrid vehicle using both an engine and a motor may be used.

DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Engine 10 Evaporative fuel processing apparatus 11 Canister 11a Vapor port 11b Purge port 11c Atmospheric port 11d Circulation port 12 Purge valve 13A, 13B, 13C Purge pump 131, 133 Motor part 132, 134 Pump part 132a, 134a Drive shaft 132b, 134b, 134c Rotating blades 132c, 134d Circulation suction ports 132d, 134e Circulation discharge ports 132e, 134f Purge suction ports 132f, 134g Purge discharge ports 14 Air filter 15 Vapor passage 16 Purge passage (circulation passage)
17 Bypass passage (circulation path)
21 Engine control circuit

Claims (9)

In an evaporative fuel processing apparatus that adsorbs evaporated fuel generated in a fuel tank to a canister via a vapor passage, and supplies and purges the adsorbed evaporated fuel to an engine via a purge passage.
A circulation path connected to the canister so that the evaporated fuel flows independently of the purge path from the canister;
A circulation pump which is provided in the circulation path and allows the evaporated fuel from the canister to flow through the circulation path;
An evaporative fuel processing apparatus comprising: concentration estimating means for detecting the magnitude of an operating load of the circulation pump and estimating the concentration of the evaporated fuel adsorbed by the canister. In claim 1,
A purge pump for generating an air flow for purging the purge passage;
A bypass passage is connected in parallel to a part of the purge passage including the canister and the purge pump, and the part of the purge passage and the bypass passage are used as the circulation passage.
An evaporative fuel processing apparatus in which the purge pump also serves as the circulation pump. In claim 2,
A fuel vapor processing apparatus comprising a purge valve in a portion of the purge passage where the purge pump is connected to the engine. In claim 2 or 3,
The purge pump is a reversible pump capable of arbitrarily reversing a discharge port and a suction port as a pump,
An evaporative fuel processing apparatus in which an on-off valve for preventing a flow from the purge pump to the canister is inserted in the bypass passage. In claim 1,
A purge pump for generating an air flow for purging the purge passage;
A purge valve is provided in a portion of the purge passage that connects the purge pump to the canister,
An evaporative fuel processing device that opens the purge valve when purging by the purge pump, and closes the purge valve when estimating the concentration of the evaporated fuel by the circulation pump. In claim 5,
The evaporative fuel processing apparatus is configured such that the circulation pump and the purge pump are driven by a single motor. In claim 6,
The circulating pump and the purge pump are rotary pumps, and an evaporative fuel processing apparatus having a common rotating shaft. In any one of Claims 1 thru | or 7,
The circulating pump is driven by a motor, and the load is detected by at least one of a current flowing through the motor and a rotation speed of the motor. In any of claims 2 to 8,
An evaporative fuel processing apparatus comprising purge pump control means for controlling the purge pump in accordance with the canister evaporative fuel concentration estimated by the concentration estimation means.

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