JPH0842430A - Fuel pump for internal combustion engine with leak detector - Google Patents

Abstract

PURPOSE:To make the leakage of fuel out of a sealing member surely detectable as making up a fuel pump so as to prevent the leaked fuel from reaching up to the outside of an engine, in this internal combustion engine fuel pump with a leak detector being suitable in use as a high-pressure output fuel pump in particular. CONSTITUTION:In this internal combustion engine fuel pump with a sealing member 11 around a pump shaft 6, it is provided with a leak detector 13 consisting of a leaked fuel inducing means 14 conducting the leaked fuel out of the sealing member 11 to an inlet system 17 of the engine, b air-fuel ratio detecting means 15 detecting an air-fuel ratio of the engine, and a leakage judging means 16 which so judges as there is a possibility that a leakage in the sealing member might be produced if the air-fuel ratio detected in this detecting means 15 is at the more rich side than the reference air-fuel ratio conformed to the engine driving state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump for an internal combustion engine, which is particularly suitable for use as a high pressure output fuel pump and has a leak detection device.

[0002]

2. Description of the Related Art In an internal combustion engine, a fuel pump is provided for supplying fuel. Some of such fuel pumps pressurize and output fuel by rotating a vane or the like. The vane and the like are mounted on a rotating shaft (hereinafter referred to as a pump shaft). Some pump shafts are configured such that the shaft end is projected to the outside and the rotary driving force is received from the outside through the shaft end.

For example, there is a structure in which such a pump shaft is interlocked with a crankshaft of an engine. In this case, one end of the pump shaft is projected to the outside and a sprocket is provided there. The sprocket on the pump shaft side and the sprocket on the crankshaft side are connected by a chain or the like to transmit the driving force. Since the pump shaft is provided so as to penetrate through the wall of the pump chamber so as to project from the inside of the pump chamber that pressurizes the fuel to the outside, a seal member (generally, a seal member is generally provided between the wall of the pump chamber and the pump shaft). , A seal ring).

By the way, there is an internal combustion engine which requires a high-pressure output fuel pump, but in such a high-pressure output fuel pump, a large load is applied to the above-mentioned seal portion between the pump chamber and the pump shaft. The durability of the seal member becomes a problem. The internal combustion engine requiring a high-pressure output fuel pump is a so-called cylinder injection internal combustion engine or a direct injection internal combustion engine (direct injection internal combustion engine), which is an internal combustion engine that injects fuel in a cylinder. There is an institution. As such an internal combustion engine, a diesel engine is widely known, but in recent years, in-cylinder injection has also been performed in a spark ignition type engine (generally referred to as a gasoline engine, since a gasoline engine corresponds thereto). Formula ones have been proposed.

In such an in-cylinder injection type internal combustion engine, in order to improve the performance of the engine and reduce the exhaust gas, the fuel injection pressure is increased to atomize the fuel spray, and the fuel injection period tends to be shortened. Further, an engine having a supercharging mechanism requires a high fuel injection pressure according to the supercharging pressure during supercharging. Therefore, the fuel supply device in the in-cylinder injection type internal combustion engine is configured so that a sufficiently high fuel injection pressure (for example, about several tens of atmospheres) can be obtained.

As a means for improving the durability of the seal member between the pump chamber and the pump shaft of the high-pressure output fuel pump installed in such an internal combustion engine, generally two seal rings are provided in series. A two-stage seal is possible.

[0007]

By the way, according to the two-stage seal as described above, even if the first stage is damaged, the second stage can be sealed and the durability of the seal member is improved.
If even the second-stage sealing member is damaged, fuel will leak from this sealing member. In this case, the fuel leaked from the seal member should not leak to the outside of the engine, so the fuel leaked from the seal member should be returned to the inside of the engine.

On the other hand, on the other hand, if it is not possible to recognize that fuel is leaking from the seal member, the engine cannot be properly managed. That is, it is desired to allow the fuel leaked from the seal member to return to the inside of the engine and to reliably detect the fuel leak from the seal member. The present invention has been devised in view of such a problem, and while configuring the fuel pump so that the fuel leaking the seal does not leak to the outside of the engine, it is possible to reliably detect the leak of the fuel from the seal member. Another object of the present invention is to provide a fuel pump for an internal combustion engine with a leak detection device.

[0009]

Therefore, a fuel pump for an internal combustion engine with a leak detection device according to the present invention according to claim 1 is
A pump chamber, a pump shaft that is connected to a driving means outside the pump chamber and rotationally drives a fuel pumping member that is mounted inside the pump chamber, and a pump shaft that is provided at a penetrating portion of the pump chamber and seals the pump chamber. A fuel pump for an internal combustion engine, which supplies a fuel to an internal combustion engine, comprising a leak detecting device for detecting a seal leak in the seal member, wherein the leak detecting device is the seal member. The leaked fuel introducing means for guiding the fuel leaked by the seal to the intake system of the internal combustion engine, the air-fuel ratio detecting means for detecting the air-fuel ratio of the internal combustion engine, and the detected air-fuel ratio detected by the air-fuel ratio detecting means are If it is richer than the reference air-fuel ratio according to the operating state of the internal combustion engine, it is composed of a leakage determination means for determining that there is a possibility that a seal leakage has occurred in the seal member. It is characterized in Rukoto.

According to a second aspect of the present invention, there is provided a fuel pump for an internal combustion engine having a leak detection device according to the first aspect, wherein the seal member directly seals the pump chamber.
The leaked fuel introducing means is formed in a two-stage series configuration including a seal member and a second seal member provided outside the first seal member and in series with the first seal member. And a second seal member from the first seal member to the intake system of the internal combustion engine to introduce the fuel leaked by the first seal member to the intake system of the internal combustion engine. The leakage determination means determines that there is a possibility that seal leakage has occurred in the first seal member when the detected air-fuel ratio is on the rich side of the reference air-fuel ratio.

According to a third aspect of the present invention, in the fuel pump for an internal combustion engine with a leak detection device according to the first or second aspect, the flow rate of the leaked fuel introduction passage is regulated to a predetermined level or less. It has a feature. A fuel pump for an internal combustion engine according to a fourth aspect of the present invention is the fuel pump for an internal combustion engine according to any one of the first to third aspects, wherein the pump shaft rotates integrally with the camshaft of the internal combustion engine. It is characterized by being directly attached to the camshaft.

According to a fifth aspect of the present invention, there is provided a fuel pump for an internal combustion engine having a leak detection device according to any one of the first to fourth aspects, wherein the leaked fuel introducing means removes the seal leaked fuel from the internal combustion engine. It is characterized in that it is introduced into the cylinder head of the engine. According to a sixth aspect of the present invention, there is provided a fuel pump for an internal combustion engine having a leakage detection device according to any one of the first to fifth aspects, wherein the internal combustion engine is a gasoline internal combustion engine.

According to a seventh aspect of the present invention, there is provided a fuel pump for an internal combustion engine having a leakage detection device according to any one of the first to sixth aspects, wherein the internal combustion engine directly injects fuel into a combustion chamber. It is characterized by being an injection type internal combustion engine. An internal combustion engine fuel pump with a leak detection device according to claim 8 is the fuel pump according to any one of claims 1 to 7, wherein the fuel pump is provided in a fuel supply path from a fuel tank to a combustion chamber. A low-pressure electric fuel pump for increasing the fuel pressure supplied to the fuel pump is provided upstream of the fuel pump in the fuel supply path.

[0014]

In the fuel pump for an internal combustion engine with a leakage detection device according to the first aspect of the present invention, when the pump shaft is rotated by being driven by the driving means outside the pump chamber, the fuel pumping member mounted in the pump chamber is It is driven to rotate and pressure-feeds the fuel to supply the fuel to the internal combustion engine.

In the portion of the pump shaft that penetrates the pump chamber,
A seal member seals the inside of the pump chamber. When a seal leak occurs in the seal member, the leaked fuel introducing means guides the leaked fuel to the intake system of the internal combustion engine. As a result, the fuel supplied to the combustion chamber of the internal combustion engine increases by the amount of the fuel leaked by the seal member. When the fuel supplied to the combustion chamber of the internal combustion engine increases in this way, the detected air-fuel ratio of the internal combustion engine detected by the air-fuel ratio detecting means is
It becomes richer than the reference air-fuel ratio according to the operating state of the internal combustion engine. In the leak detection device, the leak determination unit compares the detected air-fuel ratio by the air-fuel ratio detection unit with the reference air-fuel ratio, and determines that there is a possibility that a seal leak has occurred in the seal member. Thus, if a seal leak occurs, it can be detected (above, claim 1).

In a fuel pump for an internal combustion engine according to the present invention as defined in claim 2, the first seal member directly seals the interior of the pump chamber, and if a seal leak occurs from this first seal member, the first seal A second seal member provided in series outside the member in series with the first seal member seals the pump chamber side. When a seal leak occurs from the first seal member in this way, the leaked fuel introducing means provided between the first seal member and the second seal member to the intake system of the internal combustion engine causes The fuel leaked by the seal member is introduced into the intake system of the internal combustion engine. As a result, the fuel supplied to the combustion chamber of the internal combustion engine increases by the amount of the fuel leaked by the seal member.

When the amount of fuel supplied to the combustion chamber of the internal combustion engine increases in this way, the detected air-fuel ratio of the internal combustion engine detected by the air-fuel ratio detecting means becomes the reference air-fuel ratio corresponding to the operating state of the internal combustion engine. It is on the rich side. In the leakage detection device, the leakage determination means compares the detected air-fuel ratio by the air-fuel ratio detection means with the reference air-fuel ratio to obtain the first air-fuel ratio.
It is determined that there is a possibility of seal leakage in the seal member. Thus, if a seal leak occurs, it can be detected (the above is the second aspect).

In a fuel pump for an internal combustion engine with a leak detection device according to a third aspect of the present invention, when a seal leak occurs due to the first seal member, the second seal member comes to exert a sealing action. Therefore, the fuel is guided from the leaked fuel introduction path to the intake system of the internal combustion engine.However, since the flow rate of the leaked fuel introduction path is regulated, an abnormally large amount of fuel is supplied to the intake system through the leaked fuel introduction path. It is possible to avoid the possibility that the internal combustion engine will be difficult to operate without being supplied.

In the fuel pump for an internal combustion engine according to the present invention as set forth in claim 4, the pump shaft rotates integrally with the camshaft of the internal combustion engine to rotationally drive the fuel pressure feeding member provided in the pump chamber. Then, the fuel is pumped to supply the fuel to the internal combustion engine. In the fuel pump for an internal combustion engine with a leak detection device according to the present invention as set forth in claim 5, the leaked fuel introducing means guides the leaked fuel into the cylinder head of the internal combustion engine. It can be returned to the intake system.

In the fuel pump for an internal combustion engine with a leak detection device according to the sixth aspect of the present invention, since gasoline having poor lubricity is used as fuel, fatigue of the seal member is likely to increase. Therefore, it is very effective to detect the seal leak and to recirculate the fuel leaking into the engine into the engine, and to prevent the seal leak by the series two-stage type seal member.

In the fuel pump for an internal combustion engine with a leak detection device according to the present invention, the fuel is directly injected into the combustion chamber, but such a direct injection internal combustion engine generally requires a high fuel injection pressure. Therefore, the fuel pump must be capable of pumping fuel at high pressure. Therefore, the fatigue of the seal member is likely to increase. Therefore, it is very effective to detect the seal leak and to recirculate the fuel leaking into the engine into the engine, and to prevent the seal leak by the series two-stage type seal member.

In the fuel pump for an internal combustion engine with a leak detection device according to the present invention, the fuel in the fuel tank reaches the combustion chamber through the fuel supply passage. The partial low-pressure electric fuel pump pressurizes the fuel to a certain pressure, and thereafter, the fuel flows into the fuel pump, and the fuel pump pressurizes the fuel to a higher pressure.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment will be described with reference to FIGS. As shown in FIG. 2, a fuel pump for an internal combustion engine with a leak detection device according to a first embodiment of the present invention includes a pump body 3 directly attached to an upper portion of a cylinder head 2 of an internal combustion engine (hereinafter referred to as an engine) 1. Have

The pump body 3 sucks fuel from the fuel suction port 4 and presses the fuel by rotating a fuel pressurizing rotating body such as a vane (not shown) in a pump chamber (not shown) to pressurize the fuel from the fuel discharge port 5. The fuel pressurizing rotating body is configured to deliver the fuel, and is connected to a rotating shaft (hereinafter referred to as a pump shaft) 6. As shown in FIG. 3, the pump shaft 6 is directly connected to a cam shaft 7 provided in the cylinder head 2 via an Oldham joint 8 and is rotationally driven integrally with the cam shaft. The pump shaft 6 is pivotally supported on the case 9 of the pump main body 3 via a bearing 10. The pump chamber 6 is closer to the pump chamber than the bearing 10 so that fuel pressurized from the pump chamber does not leak. An oil seal (sealing member) 11 for sealing the oil is provided.

In particular, in this embodiment, the oil seal 11
Is a first oil seal (first seal member) 11A and a second oil seal (second seal member) 1 that are arranged in series.
It is a serial two-stage oil seal consisting of 1B.
Of these, the first oil seal 11A is provided inside the pump chamber to directly seal the inside of the pump chamber and
1B is provided in series outside the first oil seal 11A.

The pump body 3 has a case 9 fitted in a mounting hole 2A formed in the upper portion of the cylinder head 2 and fixed by bolts or the like. Case 9 and cylinder head 2
An O-ring 12 is interposed between and so that the fuel does not leak to the outside from this joint portion. The fuel pump is provided with a leak detection device 13 that detects a leak of fuel from the oil seal 11.

As shown in FIG. 1, the leak detection device 13 has a leaked fuel introducing passage (leakage fuel introducing means) 14 for guiding the fuel leaked from the oil seal 11 to the intake system of the engine 1 and the combustion of the engine 1. Air-fuel ratio sensor (air-fuel ratio detecting means) 15 for detecting the air-fuel ratio of the intake air supplied to the chamber
If the detected air-fuel ratio detected by the air-fuel ratio sensor 15 is richer than the reference air-fuel ratio corresponding to the operating state of the engine 1, there is a possibility that a seal leak has occurred from the oil seal 11. And a leakage determination means 16 for determining.

Here, the leak detection device 13 is shown in FIG.
With further description with reference to FIG. 4, the engine 1
A blow-by gas passage 18 for guiding blow-by gas to the intake passage 17 is provided in the cylinder head 2.
A bypass passage 19 is provided between the first oil seal 11 </ b> A and the second oil seal 11 </ b> B of the oil seal 11 and inside the cylinder head 2.

Therefore, when a seal leak occurs in the first oil seal 11A, the leaked fuel is the first oil seal 1
It flows into the cylinder head 2 through the bypass passage 19 from between 1A and the second oil seal 11B, is introduced into the intake passage 17 from the inside of the cylinder head 2 through the blow-by gas reducing passage 18, and further to the combustion chamber 20. Be guided. The leaked fuel introducing passage 14 is composed of the bypass passage 19, the cylinder head 2, and the blow-by gas passage 18 that guide the leaked fuel in this way. It should be noted that the leaked fuel introduction passage 14 prevents excessive fuel from being supplied to the intake system through the leaked fuel introduction passage 14 when the first oil seal 11A causes a seal leak, which makes it difficult to operate the engine. The flow rate is regulated, for example, the bypass passage 19 is formed to have a small diameter.

The air-fuel ratio sensor 15 is an oxygen concentration sensor (commonly known as a linear O ₂ sensor) provided in the exhaust passage 21 of the engine 1 for detecting the oxygen concentration in the exhaust gas. An oxygen concentration sensor (commonly known as an O ₂ sensor) that detects only the oxygen concentration is used as the air-fuel ratio sensor. As the O ₂ sensor 15 as the air-fuel ratio sensor, for example, a sensor installed to set the fuel injection amount of the engine is used, and the leakage determination means 16
Then, instead of directly using the detection result of the O ₂ sensor 15, the correction coefficient K _AF used in the O ₂ sensor feedback correction performed when setting the fuel injection amount is compared with the reference value (reference range). The leak determination means 16 is configured to determine the seal leakage.

Here, the principle of the seal leakage determination by the leakage determination means 16 will be described. When a seal leak occurs in the first oil seal 11A, the leaked fuel is leaked into the leaked fuel introduction passage 1
Since it is introduced into the intake passage 17 through 4, the air-fuel ratio changes to the rich side. A linear O ₂ sensor can detect that the air-fuel ratio has changed to the rich side at any air-fuel ratio level, but the O ₂ sensor used here changes the air-fuel ratio only near the stoichiometric air-fuel ratio (Stoichio). Can be detected. Therefore, here, it can be determined that there is a seal leak if the air-fuel ratio changes to the rich side based on the detection result of the O ₂ sensor 15 during the stoichiometric operation.

The correction coefficient K _AF is determined according to the air-fuel ratio,
When the air-fuel ratio changes to the rich side, the correction coefficient K _AF changes so as to correct the air-fuel ratio to the stoichiometric state. of course,
Even when the engine is operating normally, the air-fuel ratio changes slightly from stoichio state to rich side or lean side during stoichiometric operation, and the correction coefficient K _AF also changes each time, but the air leak ratio when seal leakage occurs The change in the fuel ratio greatly increases as compared with such a normal change, and the value of the correction coefficient K _AF deviates from the normal range. Therefore, the seal leakage can be determined based on the air-fuel ratio or the correction coefficient K _AF .

However, conversely, the reason why the air-fuel ratio changes to the rich side in this way may be other causes. That is, the air-fuel ratio increases only when a seal leak occurs.
For example, it is possible that a failure occurs in another fuel injection system such as a fuel injection valve. Therefore, if the air-fuel ratio increases,
It can be judged that there is a possibility of fuel leakage. Of course, as described above, when there is a fuel leak, this is surely detected.

The result of the seal leak determination by the leak determining means 16 is performed by turning on the check lamp 60. That is, if the seal leak is not detected, the check lamp 60 is not turned on, but when it is detected that the seal leak may occur, the check lamp 60 is turned on. If the fuel pump for the internal combustion engine is for an automobile, it is desirable to install the check lamp 60 together with other various instruments in a location with good visibility such as an instrument panel.

The characteristics of the engine equipped with the fuel pump of this embodiment will now be described. As shown in FIG. 4, this engine is a so-called in-cylinder injection type internal combustion engine or a direct injection type internal combustion engine, which is a type of engine that injects fuel in a cylinder. In addition, the intake air that has entered the combustion chamber 20 from the intake passage 17 is indicated by the arrow 2 in the combustion chamber 20.
The shape and arrangement of the intake passage 17 and the combustion chamber 20 are set so as to form a vertical swirling flow (tumble flow) as in 7.

The fuel injection valve 31 is installed so that its injection port directly faces the inside of the combustion chamber 20. Needless to say, the fuel injection valve 31 is provided for each cylinder, and the example of the engine shown here is an in-line four-cylinder type, and as shown in FIG. 5, the four fuel injection valves 31 are each directly in the combustion chamber 20. It is installed to face. In FIG. 4, 25 is an intake valve,
Reference numeral 26 is an exhaust valve, and the cam shaft 7 to which the above-mentioned pump shaft 6 is coupled is for driving the intake valve 25 in this example. Although not shown, the spark plug is installed so as to face the inside of the combustion chamber 20.

In such a cylinder injection type internal combustion engine, in order to improve the performance of the engine and reduce the exhaust gas, the fuel injection pressure is increased to atomize the fuel spray, and the fuel injection period tends to be shortened. High fuel injection pressure is required. Further, in an engine having a supercharging mechanism, a sufficiently high fuel injection pressure corresponding to the supercharging pressure is required during supercharging. Therefore, the fuel supply device provided in such a cylinder injection type internal combustion engine is configured so that a sufficiently high fuel injection pressure (for example, about several tens of atmospheres) can be obtained.

This engine has two operating modes, a stoichiometric operating mode and a lean operating mode. Since the engine output demand is low in a region where the engine load is small and the engine speed is low, the lean operating mode is selected. The fuel consumption is selected to save the fuel consumption, and the engine output demand is high in a region where the engine load is large or the engine rotation speed is high, so that the stoichiometric operation mode is selected to obtain a sufficient engine output.

Here, the fuel supply system of this engine will be described with reference to FIGS. 5 and 6. In FIGS.
Reference numeral 1 is a fuel injection valve, 32 is a fuel tank, 33 is a fuel passage provided between the fuel injection valve 31 and the fuel tank 33, and 34 is provided at an upstream portion of the fuel passage 33 on the fuel tank 32 side. The low-pressure fuel pump, 35 is a high-pressure fuel pump provided between the low-pressure fuel pump and the fuel injection valve 1,
The fuel pump for the internal combustion engine is used as this high-pressure fuel pump. Further, 36 and 37 are fuel filters provided at the inlet of the fuel passage, 38 is a check valve, 39 is a low pressure control valve as low pressure control means, 40 is a high pressure control valve as high pressure control means, and 41 is a delivery pipe. Is. The internal combustion engine fuel pump with the leak detection device (in a narrow sense, the fuel pump body 3) is provided as a high-pressure fuel pump 35.

In the fuel supply system having such a structure, the fuel pressurized to a certain extent by the low pressure fuel pump 34 is further pressurized by the high pressure fuel pump 35 (3) to increase the fuel pressure to a predetermined pressure. . At this time, the discharge pressure from the low pressure fuel pump 34 is stabilized within a predetermined range by the low pressure control valve 39, and the discharge pressure from the high pressure fuel pump 35 (3) is stabilized within a predetermined range by the high pressure control valve 40. .

Further, the fuel injection control in such a fuel supply system will be described with reference to FIG. That is, the fuel supply amount is set by the injection amount setting means 50 provided as one functional part in the ECU (electronic control unit) for the fuel injection control.
Is provided with an injection mode setting means 51. When the injection mode setting means 51 selects a stoichiometric operation mode, a stoichiometric operation fuel injection mode corresponding thereto is selected, and when a lean operation mode is selected, this is selected. The lean operation fuel injection mode is selected in accordance with. When the stoichio operation fuel injection mode is selected, the injection amount setting means 50 sets the fuel supply amount so that the air-fuel ratio is in the stoichiometric state, and when the lean operation fuel injection mode is selected, the injection amount setting means 50 , An air-fuel ratio that is appropriately lower than that in the stoichiometric state is set in advance, and the fuel supply amount is set so as to attain this low air-fuel ratio state.

[0042] In any case, the injection quantity setting means 50, first to determine the basic drive time T _B for the fuel injection valve 31, to determine the basic drive time T _B, the basic drive time T _B in the correction Various corrections are performed by the means 52 and 53 to determine the final drive time T _INJ for the fuel injection valve 31, and the fuel injection valve 3 corresponding to this drive time T _INJ.
The drive signal of 1 is output.

For this setting, various detection signals are sent from various sensors 54 to the injection amount setting means 50. The basic drive time T _B is determined based on the intake air amount Q / Ne information from the air flow sensor and the engine speed Ne information from the crank angle sensor, and the intake air amount Q / Ne information per engine revolution.

Further, the air-fuel ratio up correction for performing the air-fuel ratio up correction according to the engine speed and the engine load (the Q / Ne information includes engine load information) and O are performed.
₂ and when the sensor feedback to set the correction coefficient K _AF so that O ₂ sensor feedback correction for correcting are performed, the O ₂ sensor feedback correction is performed in O ₂ sensor feedback correcting means 52 as shown. The air-fuel ratio up correction and the O ₂ sensor feedback correction are selectively selected.

Further, a cooling water temperature correction for setting a correction coefficient K _WT according to the engine cooling water temperature, an intake air temperature correction for setting a correction coefficient K _AT according to the intake air temperature, and a correction coefficient K _AP for atmospheric pressure are set. Correction coefficient K _AC for atmospheric pressure correction and acceleration increase
The acceleration increase correction means 43 for setting the dead time (ineffective time) T for correcting the drive time according to the battery voltage.
Dead time correction for setting _D is performed.

The drive time T _INJ for the fuel injection valve 31 is determined by correcting the basic drive time T _{B according} to the following equation. _{T INJ = T B × K WT} × K AT × K AP × K AC × K AF + T D correction coefficient K corresponding to the air-fuel ratio to be used in this manner
_During stoichiometric operation, the _AF changes so as to correct the air-fuel ratio to the stoichiometric state when the air-fuel ratio changes to the rich side, and when seal leakage occurs, the air-fuel ratio and the correction coefficient K
The change in _AF becomes extremely large, and the value of the correction coefficient K _AF deviates from the normal range.

With the above structure, in the fuel pump for an internal combustion engine with the leakage detection device according to the first embodiment of the present invention, the pressure of the fuel, which has been pressurized to some extent by the low-pressure fuel pump 34, is further increased, so that the pressure of the fuel is increased. The fuel pressure suitable for high-pressure fuel injection is supplied by increasing the pressure to a predetermined pressure. In the present pump, which is such a high-pressure fuel pump, the risk of fuel leakage from the oil seal 11 is higher than in the low-pressure pump, but in the present pump, the first oil seal 11A and the second oil seal 11B of the oil seal 11 are In this case, even if the first oil seal 11A causes a seal leak, the second oil seal 11B can perform the seal, so that the fuel leak in this case can be avoided.

Moreover, since the leak detection device 13 detects and displays the seal leak from the first oil seal 11A, if the seal leak occurs, the driver can promptly deal with it. The leak detection device 13 detects the seal leak as shown in FIG.
It is performed as shown in. That is, it is determined whether the engine operation mode is the stoichiometric operation mode (step A
1) In the stoichiometric operation mode, the output from the O ₂ sensor (air-fuel ratio sensor) 15 is read (step A2).

Next, it is judged whether or not the output itself of the O ₂ sensor 15 is proper (step A3).
Based on the output of the O ₂ sensor 15 itself, the correction coefficient K _AF at the time of the O ₂ sensor feedback is changed to a value corresponding to the air concentration information (air-fuel ratio information) (step A4). Then, it is determined whether the changed correction coefficient K _AF is on the rich side with _respect to the predetermined range (step A5).

If the correction coefficient K _AF is on the rich side beyond the predetermined range, the check lamp 60 is turned on (step A6). On the other hand, if the correction coefficient K _AF is within the predetermined range,
Of course, the check lamp 60 does not light up. Also, when the operation mode is not the stoichiometric operation mode, or when the O ₂ sensor 1
If the output of No. 5 is not appropriate, the check lamp 60 does not light up, but if the output of the O ₂ sensor 15 is not appropriate, a check lamp for notifying this (a lamp different from the lamp 60 displaying leakage). ) Is turned on.

In this way, if there is a seal leak in the first oil seal 11A through the leak detection device 13, the driver can reliably detect this. Of course, even if the air-fuel ratio increases due to another cause other than the seal leak, it is determined that there is a possibility of fuel leak, and the check lamp 60 lights up. Therefore, the driver first checks the seal leak. Then, if this is normal, other causes will be checked.

Further, in this pump, since the case 9 of the pump is connected to the cylinder head 2 and the liquid,
In addition to the first oil seal 11A, the second oil seal 11
Even if a seal leak occurs in B as well, the fuel that leaks the seal surely flows into the cylinder head 2 and there is an advantage that the problem that the fuel leaks to the outside can be surely avoided.

Further, since the flow rate of the leaked fuel introduction passage 14 is regulated, even when the first oil seal 11A leaks, the pressure in the pump chamber (that is, the discharge pressure of the pump) is maintained at a predetermined level, and the leak is caused. When detecting, the abnormally large amount of fuel does not flow into the combustion chamber, and the operation of the engine can be continued even after the leakage is detected. Therefore, in the engine mounted on the vehicle, the leakage can be detected without hindering the running of the vehicle.

Next, a second embodiment will be described with reference to FIGS. The fuel pump for an internal combustion engine with a leak detection device as the second embodiment has the same structure as the pump body 3 and the state of attachment to the engine as in the first embodiment, and the leak fuel introduction passage of the leak detection device 13 (leakage fuel Since the introducing means) 14 is also constructed in the same manner as in the first embodiment, its explanation is omitted.

In the second embodiment, as shown in FIG.
The original linear O ₂ sensor is used as the air-fuel ratio sensor (air-fuel ratio detecting means) 15 that constitutes the leak detection device 13. Further, the leakage determination means 16 compares the detected air-fuel ratio itself detected by the air-fuel ratio sensor 15 with a reference air-fuel ratio according to the operating state of the engine 1 so that the detected air-fuel ratio is a certain value or more than the reference air-fuel ratio. On the rich side, it is determined that there is a possibility that seal leakage has occurred from the oil seal 11.

In such a structure, the fuel leak is detected by
This can be done, for example, as shown in FIG. First,
Read the output from the air-fuel ratio sensor 15 (step B
1) Next, it is determined whether or not the output from the air-fuel ratio sensor 15 is appropriate (step B2). If the output is appropriate, the detected air-fuel ratio is richer than the predetermined range (reference air-fuel ratio range). (Step B3).

If the detected air-fuel ratio is on the rich side of the predetermined range, the check lamp 60 is turned on (step B).
4). On the other hand, if the detected air-fuel ratio is within the predetermined range, the check lamp 60 will of course not light up. Also, the air-fuel ratio sensor 1
Even if the output of No. 5 is not appropriate, the check lamp 60 does not light, but in this case, a process such as lighting a check lamp (a lamp different from the leak display lamp 60) for notifying this is taken. To do.

Next, the third embodiment will be described with reference to FIG. The fuel pump for an internal combustion engine with a leak detection device as a third embodiment is different from the first and second embodiments in the configuration of the leak fuel introduction passage (leak fuel introduction means) 14. That is,
The configuration of the pump body 3 and the state of attachment to the engine are 1st and 2nd.
This is the same as the embodiment, but the bypass passage 19 forming the leaked fuel introduction passage 14 is different.

That is, here, as shown in FIG.
A hole 19 is formed between the first oil seal 11A and the second oil seal 11B of the oil seal 11 in the diameter direction of the case 9.
A is bored, a hole 19B is bored also in the wall portion of the cylinder head 2, and these holes 19A and 19B are connected by a pipe 19C so as to communicate with each other to form a bypass passage 19. Needless to say, a seal member (not shown) such as an O-ring is provided at the connecting portion between the holes 19A and 19B and the pipe 19C so that fuel does not leak to the outside.

With such a structure, the leakage of fuel can be detected in the same manner as in the first and second embodiments described above, and
In addition to the effect of preventing external leakage of fuel, there is an advantage that the processing for forming the bypass passage 19 can be easily performed. Next, using FIG. 11 and FIG.
A fourth embodiment will be described. In the fuel pump for the internal combustion engine with the leakage detection device according to the fourth embodiment, FIG.
2, the pump shaft 6 is connected to the camshaft 7 via the belt 61 and the pulleys 62 and 63,
The pump case 9 is fixed to a bracket 64 attached to the cylinder head 2. The oil seal 11 is composed of a first oil seal 11A and a second oil seal 11B, as in the first to third embodiments. However, the outside of the second oil seal 11B is exposed to the outside.

Then, similarly to the third embodiment, a hole 19A is formed between the first oil seal 11A and the second oil seal 11B in the diameter direction of the case 9, and a hole 19B is also formed in the wall portion of the cylinder head 2. By drilling these holes 19A,
19B are connected to each other by a pipe 19C and connected so as not to leak liquid to form a bypass path 19. Even with such a configuration, the fuel leakage from the first oil seal 11A can be detected as in the first to third embodiments.

Incidentally, in the first or second embodiment, a configuration in which the bypass 19 is omitted may be considered. In this case, the first
Although the fuel leak from the oil seal 11A alone cannot be detected, the first oil seal 11A and the second oil seal 11B are not detected.
If a leak occurs, the fuel enters the cylinder head 2 of the engine 1, so that the leak detection device 13 can detect the fuel leak in this case. Further, even if fuel leaks from the seal portion as described above, the fuel does not leak to the outside.

[0063]

As described in detail above, according to the fuel pump for an internal combustion engine with a leak detection device of the present invention as set forth in claim 1, it is connected to the pump chamber and the driving means outside the pump chamber. And a pump body for rotating and driving a fuel pumping member mounted on the pump shaft, and a pump main body having a seal member that is provided at a portion of the pump shaft penetrating the pump chamber and seals the pump chamber, and supplies fuel to an internal combustion engine. In the fuel pump for an internal combustion engine, a leak detection device for detecting a seal leak in the seal member is provided, and the leak detection device introduces the leaked fuel for introducing the fuel leaked in the seal member to the intake system of the internal combustion engine. Means, an air-fuel ratio detecting means for detecting an air-fuel ratio of the internal combustion engine, and a detected air-fuel ratio detected by the air-fuel ratio detecting means are richer than a reference air-fuel ratio according to an operating state of the internal combustion engine. If it is, it is possible to reliably detect the seal leak by including the leak determining means that determines that the seal leak may occur in the seal member. Can be dealt with promptly. Further, even if fuel leaks from the seal portion, there is no fear that the fuel will leak to the outside.

According to the fuel pump for an internal combustion engine with the leakage detection device of the present invention as set forth in claim 2, in the structure of claim 1, the seal member is a first seal member for directly sealing the pump chamber, The leaked fuel introducing means is formed in a two-stage in-series configuration including a second seal member that is provided in series with the first seal member outside the first seal member.
A leaked fuel introduction path is provided between the seal member and the second seal member and extends to the intake system of the internal combustion engine to guide the fuel leaked by the first seal member to the intake system of the internal combustion engine. The leakage determining means determines that there is a possibility that a seal leakage has occurred in the first seal member when the detected air-fuel ratio is on the rich side of the reference air-fuel ratio. When a seal leak occurs from the one seal member, the leak can be reliably detected, and the seal leak can be promptly dealt with. Further, even if a seal leak occurs from the first seal member, the second seal member
Seal leakage is prevented.

According to the fuel pump for an internal combustion engine with a leak detecting device of the present invention as defined in claim 3, the leak fuel introducing passage is configured so that the flow rate is regulated to a predetermined level or less. An abnormally large amount of fuel is not supplied to the intake system, which can prevent the internal combustion engine from becoming difficult to operate.For example, when the internal combustion engine is installed in a vehicle, fuel leakage does not hinder driving of the vehicle. Can be detected.

According to the fuel pump for an internal combustion engine with a leakage detection device of the present invention as defined in claim 4, in the structure according to any one of claims 1 to 3, the pump shaft is a camshaft of the internal combustion engine. By being directly attached to the cam shaft so as to rotate integrally, it becomes easy to hold the protruding portion of the pump shaft to the outside in the case of the cam shaft, and It becomes easy to prevent the leakage of fuel to the. Moreover, the drive system of the pump shaft can be simplified.

According to the fuel pump for an internal combustion engine with a leak detection device of the present invention as defined in claim 5, in the structure according to any one of claims 1 through 4, the leaked fuel introducing means removes the seal leaked fuel. With the configuration of guiding the leaked fuel into the cylinder head of the internal combustion engine, for example, the leaked fuel can be guided to the intake system together with the blowby gas, and a part of the leaked fuel introducing means can also be used as a flow path for storing the blowby gas. Further, when the pump shaft is directly attached to the cam shaft of the internal combustion engine so as to rotate integrally with the cam shaft, when the present configuration is applied, since the cam shaft is normally provided in the cylinder head, There is also an advantage that the leaked fuel introducing means can be easily installed.

According to the fuel pump for an internal combustion engine with a leak detection device of the present invention as defined in claim 6, in the structure as defined in any one of claims 1 to 5, the internal combustion engine is a gasoline type internal combustion engine. As a result, since gasoline has poor lubricity as a fuel, the fatigue of the seal member is likely to increase. On the other hand, detection of a seal leak and recirculation of the leaked fuel into the engine are extremely effective. The prevention of seal leakage by the automatic seal member is extremely effective, and the practicality of the fuel pump for the gasoline internal combustion engine is greatly improved.

According to the fuel pump for an internal combustion engine with a leak detection device of the present invention as set forth in claim 7, in the structure according to any one of claims 1 to 6, the internal combustion engine directly injects fuel into the combustion chamber. The direct injection type internal combustion engine, which generally requires a high fuel injection pressure and has a large sealing load on the fuel pump, is extremely effective in detecting seal leakage and returning the leaked fuel into the engine. In addition, the prevention of seal leakage by the in-line two-stage type seal member is extremely effective, which greatly improves the practicality of the fuel pump for the direct injection internal combustion engine.

According to an eighth aspect of the present invention, there is provided a fuel pump for an internal combustion engine equipped with a leak detection device, which has the structure according to any one of the first to seventh aspects. The present fuel pump is used as a high-pressure fuel pump, because a low-voltage electric fuel pump for increasing the fuel pressure supplied to the fuel pump is provided on the supply passage on the upstream side of the fuel pump in the fuel supply passage. This makes it possible to detect seal leaks and recirculate the leaked fuel into the engine at the seal portion, which is an extremely heavy burden for the high-pressure fuel pump. The prevention of is also extremely effective, and the practicality as a high-pressure fuel pump is greatly improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a fuel pump for an internal combustion engine with a leak detection device as a first embodiment of the present invention.

FIG. 2 is a top view of the internal combustion engine showing a mounted state of the pump body of the fuel pump for an internal combustion engine with a leakage detection device as the first embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view showing a mounted state of a pump body of a fuel pump for an internal combustion engine with a leakage detection device as a first embodiment of the invention, showing a portion corresponding to part A of FIG.

FIG. 4 is a diagram showing, using a cross-section of the engine, a configuration of a main part of an internal combustion engine having a fuel pump for an internal combustion engine with a leak detection device as a first embodiment of the present invention.

FIG. 5 is a fuel supply system of an internal combustion engine equipped with a fuel pump for an internal combustion engine equipped with a leak detection device according to a first embodiment of the present invention, which uses a side surface of a main part of the internal combustion engine (a direction of arrow B in FIG. 4) However, it is a figure which shows typically.

FIG. 6 is a configuration diagram schematically showing a fuel supply system of an internal combustion engine having a fuel pump for an internal combustion engine with a leak detection device as a first embodiment of the present invention.

FIG. 7 is a flow chart showing an abnormality detecting operation of the fuel pump for the internal combustion engine with the leakage detection device as the first embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a main part of a fuel pump for an internal combustion engine with a leakage detection device as a second embodiment of the present invention.

FIG. 9 is a flowchart showing an abnormality detecting operation of a fuel pump for an internal combustion engine with a leakage detection device as a second embodiment of the present invention.

FIG. 10 is a schematic configuration diagram showing a main part of a fuel pump for an internal combustion engine with a leakage detection device as a third embodiment of the present invention.

FIG. 11 is a top view of an internal combustion engine showing a mounted state of a pump body of a fuel pump for an internal combustion engine with a leakage detection device as a fourth embodiment of the present invention.

FIG. 12 is a schematic configuration diagram showing a main part of a fuel pump for an internal combustion engine with a leakage detection device as a fourth embodiment of the invention.

[Explanation of symbols]

1 Internal Combustion Engine (Engine) 2 Cylinder Head 2A Mounting Hole 3 Pump Body 4 Fuel Intake Port 5 Fuel Discharge Port 6 Rotating Shaft (Pump Shaft) 7 Camshaft 8 Oldham Joint 9 Pump Body 3 Case 10 Bearing 11 Oil Seal (Seal Member) ) 11A 1st oil seal (1st sealing member) 11B 2nd oil seal (2nd sealing member) 12 O-ring 13 Leakage detection device 14 Leakage fuel introduction path (leakage fuel introduction means) 15 Air-fuel ratio sensor (air-fuel ratio detection means) 16) Leakage judging means 17 Intake passage 17A Intake port portion 18 Blow-by gas passage 19 Bypass passage 19A, 19B hole 19C Pipe 20 Combustion chamber 21 Exhaust passage 22 Piston 23 Curved portion 24 Guide surface 25 Intake valve 26 Exhaust valve 27 Tumble flow 28 Squiche Flow 31 Fuel injection valve 32 fuel tank 33 fuel passage 34 low pressure fuel pump 35 high pressure fuel pump (fuel pump for internal combustion engine with leak detection device) 36, 37 fuel filter 38 check valve 39 low pressure control valve as low pressure control means 40 high pressure as high pressure control means Control valve 41 Delivery pipe 50 Injection amount setting means 51 Injection mode setting means 52 O ₂ sensor feedback correction means 53 Other correction means 54 Various sensors 60 Check lamp 61 Belt 62, 63 Pulley 64 Bracket

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masato Yoshida Inventor Masato Yoshida 5-3-8, Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation (72) Inventor Hideo Hatanaka No. 1 Uzumasa-cho, Ukyo-ku, Kyoto Mitsubishi Motors Engineering Co., Ltd. Company Kyoto Office (72) Inventor Tomoyuki Muraoka 1 Uzumasa Tatsumi-cho, Ukyo-ku, Kyoto Mitsubishi Motors Engineering Co., Ltd. Kyoto Office

Claims (8)

[Claims] 1. A pump chamber, a pump shaft that is connected to a driving means outside the pump chamber and rotationally drives a fuel pumping member that is mounted inside the pump chamber, and a pump shaft that penetrates through the pump chamber. A fuel pump for an internal combustion engine, comprising a pump main body having a seal member for sealing the inside of the pump chamber, comprising: a leak detecting device for detecting a seal leak in the seal member; Is a leaked fuel introducing means for guiding the fuel leaked by the seal member to the intake system of the internal combustion engine, an air-fuel ratio detecting means for detecting an air-fuel ratio of the internal combustion engine, and a detection detected by the air-fuel ratio detecting means. Leakage determination means for determining that there is a possibility that seal leakage has occurred in the seal member when the air-fuel ratio is richer than the reference air-fuel ratio according to the operating state of the internal combustion engine Characterized in that it consists, leak detection device with an internal combustion engine fuel pump. 2. A series, wherein the seal member comprises a first seal member for directly sealing the inside of the pump chamber, and a second seal member provided outside the first seal member and in series with the first seal member. The leaked fuel introducing means is formed in a two-stage structure, and the leaked fuel introducing means is provided between the first seal member and the second seal member to the intake system of the internal combustion engine, and the seal leak occurs at the first seal member. A leaked fuel introducing passage for guiding the fuel to the intake system of the internal combustion engine, and if the detected air-fuel ratio is on the rich side of the reference air-fuel ratio, the leak determination means seal-leaks at the first seal member. The fuel pump for an internal combustion engine according to claim 1, wherein it is determined that there is a possibility that the fuel is generated. 3. The leaked fuel introduction passage is regulated in flow rate to a predetermined level or less, wherein:
A fuel pump for an internal combustion engine with the leak detection device described. 4. The leak detection according to claim 1, wherein the pump shaft is directly attached to the cam shaft of the internal combustion engine so as to rotate integrally with the cam shaft of the internal combustion engine. Fuel pump for internal combustion engine with device. 5. The internal combustion engine with a leak detection device according to claim 1, wherein the leaked fuel introducing means guides the fuel leaked from the seal into the cylinder head of the internal combustion engine. Fuel pump. 6. The fuel pump for an internal combustion engine according to claim 1, wherein the internal combustion engine is a gasoline type internal combustion engine. 7. The fuel pump for an internal combustion engine according to claim 1, wherein the internal combustion engine is a direct injection type internal combustion engine that directly injects fuel into a combustion chamber. . 8. A low-pressure electric fuel for increasing the fuel pressure supplied to the fuel pump, wherein the fuel pump is provided in a fuel supply passage extending from a fuel tank to a combustion chamber, and the fuel supply passage is provided upstream of the fuel pump. A fuel pump for an internal combustion engine with a leak detection device according to any one of claims 1 to 7, characterized in that a pump is provided.