阅读说明：本技术 蒸发燃料处理装置 (Evaporated fuel treatment device ) 是由 加藤伸博 于 2019-07-01 设计创作，主要内容包括：蒸发燃料处理装置具备吸附蒸发燃料的吸附罐、吹扫配管、吹扫控制阀、泵、压力传感器以及判断部。吹扫控制阀在连通状态与切断状态之间切换,该连通状态是吸附罐与进气管连通的状态,该切断状态是将吸附罐与进气管的连通切断的状态。泵设置于吹扫配管的比吹扫控制阀靠上游侧的位置。压力传感器设置于吹扫控制阀与泵之间。判断部通过将在使吹扫控制阀为切断状态并驱动了泵时的压力传感器的第一检测值与第一基准值进行比较,接着将在使控制阀为连通状态并驱动了泵时的压力传感器的第二检测值与第二基准值进行比较,来判断吹扫路径的状态。(The evaporated fuel treatment device is provided with an adsorption tank for adsorbing evaporated fuel, a purge pipe, a purge control valve, a pump, a pressure sensor, and a determination unit. The purge control valve switches between a communication state in which the canister communicates with the intake pipe and a shut-off state in which the canister communicates with the intake pipe. The pump is provided upstream of the purge control valve in the purge pipe. The pressure sensor is arranged between the purge control valve and the pump. The determination unit determines the state of the purge path by comparing a first detection value of the pressure sensor with a first reference value when the purge control valve is in the shut-off state and the pump is driven, and then comparing a second detection value of the pressure sensor with a second reference value when the control valve is in the communication state and the pump is driven.)

1. An evaporated fuel treatment device for supplying evaporated fuel generated in a fuel tank to an intake pipe connected to an internal combustion engine, the evaporated fuel treatment device comprising:

an adsorption canister for adsorbing evaporated fuel generated in the fuel tank;

a purge pipe having a first pipe for supplying outside air to the canister and a second pipe for supplying a purge gas from the canister to a portion of the intake pipe located upstream of the throttle valve;

a purge control valve that is disposed in the second pipe and switches between a communication state in which the canister and the intake pipe communicate with each other and a shut-off state in which the canister and the intake pipe are shut off from each other;

a pump provided upstream of the purge control valve in the purge pipe and configured to pump the purge gas from the canister to the intake pipe;

a pressure sensor disposed between the purge control valve and the pump; and

a determination unit that determines the state of the purge path based on the detection value of the pressure sensor,

the determination unit determines the state of the purge path by comparing a first detection value of the pressure sensor with a first reference value when the pump is driven with the purge control valve in the shut-off state, and then comparing a second detection value of the pressure sensor with a second reference value when the pump is driven with the purge control valve in the communication state.

2. The evaporated fuel treatment apparatus according to claim 1, wherein,

the second reference value includes a downstream side reference value for determining a state of a portion of the purge path downstream of the pressure sensor and an upstream side reference value for determining a state of a portion of the purge path upstream of the pressure sensor.

3. The evaporated fuel treatment apparatus according to claim 1 or 2, wherein,

the second reference value is corrected based on the first detection value.

4. The evaporated fuel treatment apparatus according to any one of claims 1 to 3, wherein,

the pump is provided on the second pipe.

Technical Field

The present application claims priority based on japanese patent application No. 2018-134418, which was filed on 7/17/2018. The entire contents of this application are incorporated by reference into this specification. The present specification discloses a technique relating to an evaporated fuel treatment apparatus. In particular, the present invention relates to an evaporated fuel treatment apparatus capable of determining the state of a purge path.

Background

Japanese patent application laid-open No. 2006-176337 (hereinafter referred to as patent document 1) discloses an evaporated fuel treatment device that supplies evaporated fuel in a fuel tank to an intake pipe. The evaporated fuel treatment device of patent document 1 is used in a vehicle having a supercharger, and supplies purge gas to the upstream side and the downstream side of the supercharger. In patent document 1, a purge control valve, a pump, and a pressure sensor are disposed in an upstream path for supplying purge gas to an upstream side of a supercharger. In patent document 1, in order to determine the state of the upstream path (presence or absence of a defect), the pump is driven with the purge control valve opened (in a state where the purge gas is supplied to the intake pipe), and the value of the pressure sensor is detected.

Disclosure of Invention

In patent document 1, the state (presence or absence of a defect) of the purge path (upstream path) is determined by comparing the detection value of the pressure sensor with a reference value (pressure threshold). Specifically, if the detection value of the pressure sensor is equal to or less than the reference value, it is determined that the purge path is normal, and if the detection value of the pressure sensor exceeds the reference value, it is determined that an abnormality has occurred in the purge path. In this way, the evaporated fuel treatment device of patent document 1 can detect whether there is a defect in the purge path (upstream path). However, in patent document 1, a portion where a failure occurs in the purge path (a component where a failure occurs) and the content of the failure cannot be specified. When a failure occurs in the purge path, if a portion where the failure occurs or the like (the type of the failure) can be specified, the subsequent handling becomes easy. An object of the present specification is to provide an evaporated fuel treatment apparatus capable of specifying the type of a failure when a failure has occurred in a purge path.

A first technique disclosed in the present specification relates to an evaporated fuel treatment apparatus that supplies evaporated fuel generated in a fuel tank to an intake pipe connected to an internal combustion engine. The evaporated fuel treatment apparatus may include an adsorption tank, a purge pipe, a purge control valve, a pump, a pressure sensor, and a determination unit. The canister may adsorb the evaporated fuel generated in the fuel tank. The purge pipe may include a first pipe for supplying the outside air to the canister and a second pipe for supplying the purge gas from the canister to a portion of the intake pipe located on the upstream side of the throttle valve. The purge control valve may be disposed in the second pipe. In addition, the purge control valve may be switched between a communication state in which the canister communicates with the intake pipe and a shut-off state in which the canister communicates with the intake pipe is shut off. The pump may be provided upstream of the purge control valve in the purge pipe. Further, the pump may be used to pump the purge gas from the canister to the intake pipe. A pressure sensor may be disposed between the purge control valve and the pump. The determination portion may determine the state of the purge path based on a detection value of the pressure sensor. In the evaporated fuel treatment device, the determination unit may determine the state of the purge path by comparing a first detection value of the pressure sensor when the pump is driven with the purge control valve in the shut-off state with a first reference value, and then comparing a second detection value of the pressure sensor when the pump is driven with the purge control valve in the communication state with a second reference value.

According to the evaporated fuel treatment apparatus of the first technique, a second technique disclosed in the present specification may be such that the second reference value includes a downstream side reference value for determining a state of a portion of the purge path downstream of the pressure sensor and an upstream side reference value for determining a state of a portion of the purge path upstream of the pressure sensor.

According to the evaporated fuel treatment device of the first or second technique described above, a third technique disclosed in this specification may be such that the second reference value is corrected based on the first detection value.

In the evaporated fuel treatment apparatus according to any one of the first to third techniques, a fourth technique disclosed in the present specification may be such that the pump is provided in the second pipe.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the first technique, it is possible to determine whether or not a failure such as gas leakage has occurred in a range from the pump to the purge control valve by comparing the first detection value with the first reference value. Specifically, when the purge control valve is closed and the pump is driven, if the pump is normally driven and a breakage or the like does not occur in the purge path, the detection value (closing pressure) of the pressure sensor increases in accordance with the discharge capacity of the pump. Therefore, by setting the first reference value according to the discharge capacity of the pump and comparing the detection value (first detection value) of the pressure sensor when the purge control valve is closed and the pump is driven with the first reference value, it is possible to determine whether or not a failure has occurred in the range from the pump to the purge control valve. The first reference value is set to a value slightly lower than the closing pressure when no malfunction occurs in the pump and the purge path. Thus, if the first detection value exceeds the first reference value, it can be confirmed that no malfunction has occurred between the pump and purge control valve. On the other hand, if the first detection value is equal to or less than the first reference value, it can be confirmed that a failure (gas leakage, failure of the pump itself) has occurred between the pump and the purge control valve. Further, as the failure of the pump itself, there are mechanical failure (failure of a motor or the like), structural failure (failure in sealing of a member constituting the pump), complete blockage of the pump outlet (or a filter provided in the pump outlet), and the like. That is, the failure of the pump itself indicates a state in which the gas cannot be discharged from the pump.

In the first technique, after the comparison between the first detection value and the first reference value is performed, the purge control valve is further opened to acquire the detection value (second detection value) of the pressure sensor. Further, the purge control valve may be changed from the shut-off state to the communication state (closed → open) while the pump is being driven, or the pump may be stopped after the first detection value is acquired, and the pump may be driven again after the purge control valve is changed to the communication state. When the purge control valve is brought into a communication state, if the pump is normally driven and the purge gas normally flows through the intake pipe, the detection value of the pressure sensor becomes a value (second detection value) lower than the first detection value. Therefore, by setting the second reference value according to the discharge capacity of the pump and comparing the second detection value with the second reference value, it is possible to determine the state of the purge path (whether or not a defect such as clogging occurs in the purge pipe). According to the first technique, it is possible to determine not only whether a failure has occurred in the purge path, but also the type of the failure.

According to the second technique, when a failure occurs in the purge path, the failure occurrence site can be specified in more detail. As described above, when the purge control valve is brought into the communication state and the pump is driven, if the purge path is normal, the detection value (second detection value) of the pressure sensor is lower than the first detection value. Therefore, when a malfunction (clogging) occurs downstream of the pressure sensor, the second detection value is higher than the normal value (second reference value). Therefore, when the second reference value is set to a value slightly higher than the pressure at which no malfunction occurs in the pump and the purge path and the second detection value is compared with the second reference value, if the second detection value is a value lower than the second reference value, it can be confirmed that no malfunction occurs downstream of the pressure sensor. On the other hand, if the second detection value is equal to or greater than the second reference value, it can be confirmed that a defect (clogging) has occurred downstream of the pressure sensor.

However, when a failure (clogging) occurs upstream of the pressure sensor, the flow rate of the purge gas purged from the pump to the portion where the pressure sensor is disposed decreases, and the detection value (second detection value) of the pressure sensor becomes lower than the normal value (second reference value). Therefore, when the second reference value is set to a value slightly lower than the pressure at which no malfunction occurs in the pump and the purge path and the second detection value is compared with the second reference value, if the second detection value is a value higher than the second reference value, it can be confirmed that no malfunction occurs upstream of the pressure sensor. On the other hand, if the second detection value is equal to or less than the second reference value, it can be confirmed that a defect (clogging) has occurred upstream of the pressure sensor.

In the second technique, the second reference value includes a downstream side reference value and an upstream side reference value. That is, the second reference value has a value (downstream side reference value) slightly higher than the pressure at the time when no malfunction occurs in the pump and the purge path and a value (upstream side reference value) slightly lower than the pressure at the time when no malfunction occurs in the pump and the purge path. Thus, the position of the purge path where the failure has occurred (i.e., the type of the failure) can be specified more specifically.

According to the third technique, the state (presence or absence of a failure) of the purge path can be determined more accurately. The first detection value (closing pressure) depends on the ejection capability of the pump and the concentration of the purge gas. That is, even if the discharge capacity of the pump is the same, the higher the concentration of the purge gas is, the higher the first detection value is. Similarly, the second detection value is also set to be higher as the concentration of the purge gas is higher. Therefore, by correcting the second reference value based on the first detection value, the state of the purge path can be determined more accurately. Specifically, the concentration of the purge gas is estimated using the first detection value, a correction coefficient is calculated based on the estimated purge gas concentration, and the second reference value is corrected by multiplying the second reference value by the correction coefficient.

According to the fourth technique, since the pressure loss of the canister is not affected, the state of the purge path can be determined more accurately.

Drawings

Fig. 1 shows a schematic diagram of an evaporated fuel treatment apparatus.

Fig. 2 shows a modification of the evaporated fuel treatment apparatus.

Fig. 3 shows a flow of determining the state of the purge path.

Fig. 4 shows a relationship between the state of the purge path and the detection value of the pressure sensor.

Fig. 5 shows a flow of correcting the second reference value.

Fig. 6 shows the relationship between the purge gas concentration and the corrected second reference value.

Detailed Description

(evaporated fuel treatment apparatus)

Referring to fig. 1, evaporated fuel treatment apparatus 100 is described. The evaporated fuel processing apparatus 100 is mounted on a vehicle such as an automobile. The evaporated fuel processing apparatus 100 includes: an intake system 10 for supplying air to the engine 2; and a purge gas supply device 50 that supplies the evaporated fuel generated in the fuel tank 32 to the intake system 10.

(air intake system)

The intake system 10 includes an intake pipe 6, a throttle valve 4, and an air cleaner 8. The intake pipe 6 is connected to the engine 2. The intake pipe 6 is a pipe for supplying air to the engine 2. A throttle valve 4 is provided in the intake pipe 6. The amount of air flowing into the engine 2 is controlled by adjusting the opening degree of the throttle valve 4. That is, the throttle valve 4 controls the intake air amount of the engine 2. The throttle valve 4 is controlled by an ECU (Engine Control Unit) 52.

An air cleaner 8 is connected to the intake pipe 6 at a position upstream of the throttle valve 4. The air cleaner 8 has a filter for removing foreign matters in the air flowing into the intake pipe 6. When the throttle valve 4 is opened, air that has passed through the air cleaner 8 flows through the intake pipe 6 and is drawn into the engine 2. The engine 2 combusts fuel and air therein, and discharges the combusted fuel and air to an exhaust pipe (not shown). A flow rate sensor (not shown) is disposed in the vicinity of the air cleaner 8. The flow sensor detects the amount of air introduced into the intake pipe 6 from the atmosphere. Further, a supercharger may be disposed upstream of the throttle valve 4 in the intake pipe 6.

(purge gas supply device)

The purge gas supply device 50 supplies the evaporated fuel generated in the fuel tank 32 to the engine 2 through the intake pipe 6. The purge gas supply device 50 includes an adsorption tank 40, a purge pipe 20, a purge control valve 22, a pump 26, and a pressure sensor 24. The canister 40 includes activated carbon 40d therein, and the evaporated fuel generated in the fuel tank 32 is adsorbed by the activated carbon 40 d. Thereby, the evaporated fuel generated in the fuel tank 32 is prevented from being released into the atmosphere.

The canister 40 is provided with an atmospheric port 40a, a purge port 40b, and a fuel tank port 40 c. The first pipe 20a is connected to the atmosphere port 40 a. The first pipe 20a connects the air port 40a and the air filter 28. The second pipe 20b is connected to the purge port 40 b. The third pipe 30 is connected to the tank port 40 c. The third pipe 30 connects the tank port 40c and the fuel tank 32. When the purge gas is supplied (purged) to the intake pipe 6, the outside air is introduced into the canister through the first pipe 20a, and the purge gas is supplied to the intake pipe 6 through the second pipe 20 b. The first pipe 20a and the second pipe 20b can be collectively referred to as a purge pipe 20. Further, a purge path is formed from an end portion of the first pipe 20a (the air cleaner 28) to an end portion of the second pipe 20b (the intake pipe 6 side).

As described above, the activated carbon 40d is accommodated inside the canister 40. Ports 40a, 40b, and 40c are provided on 1 wall surface of the adsorption tank 40 out of the wall surfaces facing the activated carbon 40 d. There is a space between the inner wall of the canister 40 on the side where the ports 40a-40c are provided and the activated carbon 40 d. In addition, the first partition plate 40e and the second partition plate 40f are fixed to the inner wall of the canister 40 on the side where the ports 40a to 40c are provided. The first partition plate 40e separates the space between the activated carbon 40d and the inner wall of the canister 40 between the atmosphere port 40a and the purge port 40 b. The first partition plate 40e extends to a space on the side opposite to the side where the ports 40a-40c are provided. The second partition plate 40f separates the space between the activated carbon 40d and the inner wall of the canister 40 between the purge port 40b and the fuel tank port 40 c.

The activated carbon 40d is used to adsorb vaporized fuel from the gas flowing from the fuel tank 32 into the canister 40 through the third pipe 30. The gas from which the evaporated fuel is removed passes through the first pipe 20a and the air filter 28, and is released into the atmosphere. Canister 40 prevents the vaporized fuel in fuel tank 32 from being released into the atmosphere. The evaporated fuel adsorbed by the activated carbon 40d is supplied to the second pipe 20b as a purge gas together with the air introduced from the first pipe 20 a.

The first partition plate 40e separates a space connected to the atmosphere port 40a and a space connected to the purge port 40 b. Therefore, the activated carbon 40d is necessarily interposed in the flow path between the ports 40a, 40 b. The first partition plate 40e prevents the gas containing the evaporated fuel from being released into the atmosphere, and prevents the gas (air) introduced from the atmosphere port 40a from directly moving from the purge port 40b into the second pipe 20 b. The second partition plate 40f separates a space connected to the purge port 40b and a space connected to the tank port 40 c. The second partition plate 40f prevents the gas (evaporated fuel) flowing into the canister 40 from the fuel tank port 40c from directly moving into the second pipe 20 b. By providing the first partition plate 40e and the second partition plate 40f, the mixed gas of the evaporated fuel adsorbed by the activated carbon 40d and the air introduced from the first pipe 20a is supplied as the purge gas to the second pipe 20 b.

The purge pipe 20 constitutes a path (purge path) for supplying the evaporated fuel adsorbed in the canister 40 to the intake pipe 6 as a purge gas. As described above, the purge pipe 20 includes the first pipe 20a and the second pipe 20 b. The first pipe 20a connects the canister 40 and the air filter 28. The air supplied to the canister 40 flows through the first pipe 20 a. The second pipe 20b connects the canister 40 and the intake pipe 6. Specifically, the second pipe 20b is connected to the upstream side of the throttle valve 4 and between the throttle valve 4 and the air cleaner 8. When the supercharger is disposed in the intake pipe 6 upstream of the throttle valve 4, the second pipe 20b is connected to the upstream side of the supercharger. A mixed gas (purge gas) of the air supplied to the canister 40 through the first pipe 20a and the evaporated fuel adsorbed in the canister 40 flows through the second pipe 20 b. As a material of the purge pipe 20, a flexible material such as rubber or resin, a metal material such as iron, or the like is used.

The purge control valve 22 is disposed at a position downstream of the canister 40 on the purge pipe 20 (second pipe 20 b). When the purge control valve 22 is in the shut-off state, the purge gas is stopped by the purge control valve 22. When the purge control valve 22 is opened (brought into a communication state) and the pump 26 is driven, the purge gas is supplied into the intake pipe 6. Specifically, when the pump 26 is driven, air is supplied to the canister 40 through the first pipe 20a, and a mixed gas (purge gas) of the air and the evaporated fuel adsorbed in the canister 40 is supplied to the intake pipe 6 through the second pipe 20 b. The purge control valve 22 is an electronic control valve and is controlled by the ECU 52. Specifically, the purge control valve 22 is duty-controlled by a signal output from the ECU 52. That is, the ECU 52 adjusts the valve opening time of the purge control valve 22 by adjusting the duty ratio of the output signal. The ECU 52 also performs duty control of the throttle valve 4 to adjust the opening degree (valve opening time) in the same manner as the purge control valve 22.

The pump 26 is disposed in the purge pipe 20 (second pipe 20b) at a position between the canister 40 and the purge control valve 22. The pump 26 uses a so-called vortex pump (also referred to as a cascade pump, a friction pump), a centrifugal pump, or the like. The pump 26 is controlled by the ECU 52. Although not particularly limited, a filter for removing foreign matter may be provided at the discharge port of the pump 26.

The pressure sensor 24 is disposed between the pump 26 and the purge control valve 22. The pressure sensor 24 is capable of detecting the pressure within the portion of the purge line 20 downstream of the pump 26. Further, the pressure sensor 24 may be of a type that detects an absolute pressure, or may be of a type that detects a gauge pressure. The pressure sensor 24 may be replaced with a differential pressure sensor (capable of obtaining substantially the same detection value as that of the pressure sensor for detecting the gauge pressure) for detecting the pressure difference between the front and rear of the pump 26. The detection value of the pressure sensor 24 is input to the determination unit 54 in the ECU 52.

The determination unit 54 is a part of the ECU 52, and is disposed integrally with other parts of the ECU 52 (for example, a part that controls the engine 2). However, the determination unit 54 may be independent of the ECU 52. The determination unit 54 includes a CPU, and memories such as ROM and RAM. As will be described in detail later, the determination unit 54 determines the state (presence or absence of a defect) in the purge path based on the reference value (threshold value) stored in the memory and the detection value of the pressure sensor 24.

(modification of evaporated Fuel treatment apparatus)

Referring to fig. 2, evaporated fuel treatment apparatus 200 will be described. The evaporated fuel treatment apparatus 200 is a modification of the evaporated fuel treatment apparatus 100, and the purge gas supply apparatus 50a is different in configuration from the purge gas supply apparatus 50 of the evaporated fuel treatment apparatus 100. In the evaporated fuel treatment apparatus 200, the same reference numerals as those given to the evaporated fuel treatment apparatus 100 are given to substantially the same configuration as that of the evaporated fuel treatment apparatus 100, and the description thereof may be omitted.

In the evaporated fuel treatment apparatus 200, the pump 26 and the pressure sensor 24 are disposed in the first pipe 20 a. Specifically, the pump 26 and the pressure sensor 24 are disposed between the air cleaner 8 and the canister 40 (the air port 40 a). The pressure sensor 24 is disposed downstream of the pump 26 (on the canister 40 side). In the evaporated fuel treatment apparatus 200 as well, when the purge control valve 22 is opened and the pump 26 is driven, air is supplied to the canister 40 through the first pipe 20a, and a mixed gas (purge gas) of the air and the evaporated fuel adsorbed in the canister 40 is supplied to the intake pipe 6 through the second pipe 20 b.

(purge route State judging Process 1)

As described above, the determination unit 54 determines the state (presence or absence of a defect) in the purge path using the detection value of the pressure sensor 24. A state determination process 1 in the purge path in the evaporated fuel processing apparatus 100 will be described with reference to fig. 3 and 4. The determination unit 54 determines the state of a portion of the purge path located between the pump 26 and the purge control valve 22 (including the pump 26 and the purge control valve 22 themselves).

First, the pump 26 is driven in a state where the purge control valve 22 is closed (step S2) (step S4). When the pump 26 is driven in a state where the purge control valve 22 is closed, the pressure between the pump 26 and the purge control valve 22 (the detection value of the pressure sensor 24) rises in accordance with the output of the pump 26. However, if a failure occurs in the pump 26 (a sealing failure of a component constituting the pump 26, a blockage in an output port of the pump 26, or the like), or if a portion of the purge pipe 20 (the second pipe 20b) located between the pump 26 and the purge control valve 22 is damaged (pipe leakage), the pressure between the pump 26 and the purge control valve 22 (the detection value of the pressure sensor 24) does not sufficiently increase.

If the above-described failure does not occur between the pump 26 and the purge control valve 22, the detection value of the pressure sensor 24 exceeds the reference value a (reference numeral 60 in fig. 4), and if the above-described failure occurs, the detection value of the pressure sensor 24 is lower than the reference value a (reference numeral 62 in fig. 4). The reference value a is a value set in advance in accordance with the capacity of the pump 26, and is stored in the memory of the determination unit 54. The reference value a is a threshold value for determining whether or not the above-described failure has occurred, and is a value lower than the pressure between the pump 26 and the purge control valve 22 when the above-described failure has not occurred. Hereinafter, a state in which a failure of the pump 26 itself or a failure such as breakage of the second pipe 20b occurs may be referred to as "failure a".

After the pump 26 is driven (step S4), the pressure P1 (first detection value) at which the detection value of the pressure sensor 24 is stabilized is acquired (step S6). Next, the determination unit 54 compares the pressure P1 with the reference value a (step S8). When the pressure P1 is equal to or less than the reference value a (no in step S8, and reference sign 62 in fig. 4), the determination unit 54 determines that the above-described failure (abnormality a) has occurred (step S20), and notifies it via a warning lamp (not shown) (step S26). When the pressure P1 exceeds the reference value a (step S8: "yes", mark 60 in fig. 4), the process proceeds to step S10, and the purge control valve 22 is opened at a predetermined opening degree.

When the purge control valve 22 is opened, the purge gas is supplied to the intake pipe 6, and the pressure between the pump 26 and the purge control valve 22 (the detection value of the pressure sensor 24) is lower than the pressure P1. However, when clogging (partial clogging) occurs in a portion of the purge pipe 20 (the second pipe 20b) downstream of the pressure sensor 24 or the purge control valve 22 is not normally opened (such as when the purge control valve 22 is fixed in a closed state), the flow rate of the purge gas moving from the purge pipe 20 to the intake pipe 6 decreases, and the detection value of the pressure sensor 24 does not sufficiently decrease. In this case, the detection value of the pressure sensor 24 is larger than the reference value b (reference numeral 64 of fig. 4).

When the portion of the purge pipe 20 downstream of the pressure sensor 24 is completely closed, the detection value of the pressure sensor 24 hardly decreases from the pressure P1 (does not decrease from the mark 60) even when the purge control valve 22 is opened. That is, if a flow path downstream of the pressure sensor 24 in the flow path of the purge gas is normally secured, the detection value of the pressure sensor 24 is lower than the reference value b (reference numeral 66 in fig. 4), and if the flow path downstream of the pressure sensor 24 in the flow path of the purge gas is narrower than the normal state, the detection value of the pressure sensor 24 is higher than the reference value b (reference numeral 64 in fig. 4). The reference value b is a threshold value for determining whether or not a failure has occurred downstream of the pressure sensor 24, and is a value higher than the pressure between the pump 26 and the purge control valve 22 when no failure has occurred downstream of the pressure sensor 24. The reference value b is an example of the downstream reference value. Hereinafter, a state in which a failure has occurred downstream of the pressure sensor 24 may be referred to as "abnormality B".

When the partial clogging occurs upstream of the pressure sensor 24, the flow rate of the purge gas flowing to the portion where the pressure sensor 24 is disposed decreases, and the detection value of the pressure sensor 24 is also lower than the normal value. In this case, the detection value of the pressure sensor 24 is smaller than the reference value c (reference numeral 68 of fig. 4). For example, when a partial blockage occurs in a portion of the purge pipe 20 (the second pipe 20b) upstream of the pressure sensor 24 or in an output port (including a filter provided at an outlet) of the pump 26, the detection value of the pressure sensor 24 is smaller than the reference value c.

If a flow path upstream of the pressure sensor 24 in the flow path of the purge gas is normally secured, the detection value of the pressure sensor 24 is higher than the reference value c (reference numeral 66 in fig. 4), and if the flow path upstream of the pressure sensor 24 in the flow path of the purge gas is narrower than the normal state, the detection value of the pressure sensor 24 is lower than the reference value c (reference numeral 68 in fig. 4). The reference value c is a threshold value for determining whether or not a failure has occurred upstream of the pressure sensor 24, and is a value lower than the pressure between the pump 26 and the purge control valve 22 when no failure has occurred upstream of the pressure sensor 24. The reference value c is an example of the upstream side reference value. Hereinafter, a state in which a failure has occurred upstream of the pressure sensor 24 may be referred to as "abnormal C".

The reference values b and c are values set in advance in accordance with the capacities of the purge control valve 22 and the pump 26, and are stored in the memory of the determination unit 54. As described above, the reference value B and the reference value C are threshold values for determining whether or not the abnormality B or the abnormality C is generated. Therefore, if the detection value of the pressure sensor 24 is between the reference value b and the reference value c, it indicates that the flow path of the purge gas is normally secured (the purge path is normal).

Returning to the description of the state judgment process 1. As shown in fig. 3, after the purge control valve 22 is opened in a state where the pump 26 is driven (step S10), the pressure P2 (second detection value) at which the detection value of the pressure sensor 24 is stable is acquired (step S12). Next, the judgment unit 54 compares the pressure P2 with the reference value b (steps S14 and S16). When the pressure P2 is greater than the reference value B (step S14: "no", mark 64 in fig. 4), the determination unit 54 determines that "abnormality B" has occurred (step S22), and notifies it via a warning lamp (step S26). On the other hand, when the pressure P2 is less than the reference value b (step S14: YES), the flow proceeds to step S16, where the pressure P2 is compared with the reference value c. When the pressure P2 is less than the reference value C (step S16: "no", mark 68 in fig. 4), the determination unit 54 determines that "abnormality C" has occurred (step S24), and notifies it via a warning lamp (step S26). On the other hand, if the pressure P2 is greater than the reference value c (step S16: "YES"), the routine proceeds to step S18, where it is determined that the purge path is normal. Further, the order of step S14 and step S16 is arbitrary, and step S14 may be performed after step S16 is performed.

As described above, in the evaporated fuel treatment device 100, the pressure P1 (first detection value) when the pump 26 is driven with the purge control valve 22 closed is detected, and then the pressure P2 (second detection value) when the pump 26 is driven with the purge control valve 22 open is detected, whereby it is possible to determine not only whether a failure has occurred in the purge path, but also to specify the type of the failure ("abnormal a", "abnormal B", or "abnormal C") when a failure has occurred in the purge path. By specifying the type of the failure, maintenance and the like can be facilitated later.

(purge route State judging Process 2)

As described above, in the evaporated fuel processing apparatus 100, the pressure P1 is acquired and then the pressure P is acquiredBy comparing 1 with the reference value a and then comparing the pressure P2 with the reference values b and c after the pressure P2 is acquired, it is possible to determine whether or not there is a failure in the purge path and to specify the type of failure. In the above-described "purge path state determination process 1", the reference values a, b, and c are fixed values stored in the memory of the determination section 54. However, the higher the concentration of the purge gas, the higher the pressure in the purge piping, with the same flow rate of the purge gas. Therefore, in the present state determination process, the reference values b and c are corrected according to the concentration of the purge gas, and the threshold value for the occurrence of the malfunction is varied. Next, the state determination process 2 will be explained with reference to fig. 5 and 6. In this process, the reference value b stored in the memory of the determination section 54 is compared with the reference value b between the step of comparing the pressure P1 with the reference value a (step S8) and the step of opening the purge control valve 22 (step S10)₀And c₀Correction is performed, and reference values b and c for comparison are calculated. That is, in the present process, the reference values a and b when the concentration of the purge gas is a specific concentration (for example, 20%) are stored in the determination unit 54₀、c₀。

First, in the case where the pressure P1 exceeds the reference value a (step S8: YES), the correction coefficient α is calculated based on the pressure P1 (step S40). For example, as shown in fig. 6, when the purge gas concentration calculated from the pressure P1 is 20% (reference numeral 70), the correction coefficient α is set to "1". A reference value b stored in the memory of the judging section 54₀And c₀Multiplied by "1" (steps S42, S44), and compared with the pressure P2. That is, the reference value b stored in the memory of the determination unit 54 is directly used₀And c₀. When the purge gas concentration calculated from the pressure P1 is 40% (reference numeral 72), the correction coefficient α is set to a value larger than "1" and the reference value b is compared with the reference value b₀And c₀Correction is performed (steps S42, S44). On the other hand, when the purge gas concentration calculated from the pressure P1 is 10% (reference 74), the correction coefficient α is set to a value smaller than "1" and the reference value b is set to the reference value b₀And c₀Correction is performed (steps S42, S44). In this way, by using pressureP1 is corrected to obtain the reference values b and c, whereby it is possible to more accurately judge whether or not a malfunction has occurred in the purge path.

In the above-described state determination processes 1 and 2, the example of determining the state of the purge path of the evaporated fuel treatment device 100 has been described, but the above-described state determination process can also be applied to the evaporated fuel treatment device 200.

(other embodiments)

In the technique disclosed in the present specification, it is important to arrange an adsorption tank, a purge control valve, a pump, and a pressure sensor in a purge path, determine whether or not there is a failure in the purge path using a detection value (closing pressure) of the pressure sensor when the pump is driven with the purge control valve closed, and then determine whether or not there is a failure in the purge path using a detection value of the pressure sensor when the pump is driven with the purge control valve open. Therefore, the purge control valve may be disposed downstream of the canister and in the order of the pump, the pressure sensor, and the purge control valve from upstream of the purge path, and the positions where these components are disposed are not limited to the above-described embodiment. For example, the pump may be disposed in the first pipe, and the pressure sensor may be disposed in the second pipe.

The second reference value does not need to have the reference value b (downstream reference value) and the reference value c (upstream reference value). The comparison of the second detection value with the second reference value is performed after the comparison of the first detection value with the first reference value and the confirmation of the occurrence of the "abnormality a" described above. Therefore, regardless of whether the second reference value is the reference value B (the downstream-side reference value) or the reference value C (the upstream-side reference value), it is possible to determine whether or not an abnormality ("abnormality B" or "abnormality C") different from "abnormality a" has occurred by comparing the second detection value with the second reference value.

The embodiments of the present invention have been described in detail, but these are only examples and are not intended to limit the claims. The techniques described in the claims include those obtained by variously changing and modifying the specific examples illustrated above. The technical elements described in the specification and drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The techniques illustrated in the present specification and drawings are techniques for achieving a plurality of objects at the same time, and achieving one of the objects is a technique having technical usefulness.