JPH1182177A - Gaseous fuel supply system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wear of a seat part and a sliding part of a fuel injection valve at the time of supplying gaseous fuel without lubricating property. SOLUTION: A gaseous fuel supply system for an internal combustion engine is provided with a fuel injection vallve 2 for injecting and supplying gaseous fuel to the internal combustion engine 1 through a fuel piping 6, and a feed oil pipe 9 connecting the fuel piping 6 on the upper stream of the fuel injection valve 2 to an oil pump 10 for force-feeding oil for lubricating the internal combustion engine 1. Oil is mixed with the fuel piping 6 through the feed oil pipe 9. Oil is thus mixed with the nonlubricating fuel in the fuel piping 6 from the oil feed pipe 9 to impart lubricity to a seat part and a sliding part of the fuel injection valve 2, thereby preventing wear and improving durability. At the same time, wear of seat parts and sliding parts of an intake valve 16 and exhaust valve 17 on the downstream of the fuel injection valve 2 can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas fuel supply device for an internal combustion engine that supplies gas fuel to the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a prior art document relating to a gas fuel supply device for an internal combustion engine, there is Japanese Patent Application Laid-Open No. 3-260370.
The one disclosed in Japanese Patent Application Publication No. HEI 10-203 (1995) is known. In this example, the structure of a fuel injection valve (gas injector) for injecting gas fuel represented by natural gas into an internal combustion engine is shown.

[0003]

However, since gas fuel has no lubricity, the seats and sliding parts of the fuel injection valve exhibit remarkable wear as compared with liquid fuel, resulting in poor sealing and poor metering accuracy. There was a problem of lowering.

Accordingly, the present invention has been made to solve such a problem, and it is possible to prevent wear of a seat portion, a sliding portion, and the like of a fuel injection valve when supplying non-lubricating gas fuel. It is an object to provide a gas fuel supply device for an internal combustion engine.

[0005]

According to the first aspect of the present invention, the oil from the oil supply pipe is mixed with the non-lubricious gas fuel in the fuel pipe, and the seat portion of the fuel injection valve is provided. By providing lubrication to the sliding parts and the sliding parts, wear is prevented and durability is improved, and wear of seats and sliding parts of intake valves and exhaust valves downstream of the fuel injection valve can be suppressed. The effect is obtained.

In the gas fuel supply device for an internal combustion engine according to the second aspect, in order to impart lubricity to the seat portion and the sliding portion of the fuel injection valve, the oil mixing amount is 0.1 to 0.2 wt% of the fuel amount. ]
By this, the oil consumption due to this can be suppressed to, for example, about 10% during a so-called maintenance interval as a normal oil replacement cycle, and it is necessary to increase the oil pan capacity of the internal combustion engine. And the desired effect can be obtained.

In the gas fuel supply device for an internal combustion engine according to the third aspect, when the internal combustion engine is in an operating state in which the cooling water temperature exceeds 70 ° C., the exhaust gas purifying catalyst mounted downstream of the exhaust pipe is activated. Therefore, the oil shut-off valve installed in the middle of the oil supply pipe is opened, oil is mixed into the gas fuel in the fuel pipe, and this oil component is uncommitted after combustion in the internal combustion engine. Even if the exhaust gas is discharged to the exhaust pipe side as the fuel HC, it can be purified by the exhaust gas purifying catalyst.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

FIG. 1 is a schematic diagram showing an entire configuration of a gas fuel supply device for an internal combustion engine according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an internal combustion engine using natural gas as fuel, and 2 denotes a fuel injection valve mounted on an intake pipe 3 of each cylinder of the internal combustion engine 1. Gas fuel (hereinafter simply referred to as “fuel”) is injected and supplied into the combustion chamber 4 of each cylinder. This fuel is supplied from the high-pressure fuel cylinder 5 to the fuel injection valve 2 via the fuel pipe 6 through the fuel cutoff valve 7 and the pressure reducing valve 8. At this time, the fuel from the high-pressure fuel cylinder 5 is reduced in pressure by the pressure reducing valve 8 from about 200 atm to about 3 atm. In the middle of the fuel pipe 6 between the pressure reducing valve 8 and the fuel injection valve 2, a fuel supply pipe 9 having a nozzle 9 a at a tip is connected. The upstream side of the oil supply pipe 9 is connected to an oil pump 10 for pumping and pumping oil in an oil pan 1a to lubricate the internal combustion engine 1. Therefore, a part of the oil pressurized to about 4 atm from the oil pump 10 is supplied to the oil supply pipe 9. An oil cut-off valve 11 is mounted in the middle of the oil supply pipe 9.
A check valve 12 is mounted between the nozzle 1 and the nozzle 9a of the oil supply pipe 9. An oil filter 13 for filtering the pumped oil is mounted on the upstream side of the oil pump 10.

Reference numeral 14 denotes an oil level sensor mounted on the internal combustion engine 1. The oil level sensor 14 detects the oil level O stored in the oil pan 1 a of the internal combustion engine 1.
L is detected sequentially. Reference numeral 15 denotes a water temperature sensor mounted on the internal combustion engine 1.
Are sequentially detected. An intake valve 16 is provided on the inlet side of the combustion chamber 4 of each cylinder of the internal combustion engine 1, and an exhaust valve 17 is provided on the outlet side. The exhaust pipe 1 of the internal combustion engine 1
An exhaust gas purifying catalyst 19 is mounted downstream of 8.

Reference numeral 20 denotes an ECU (Electronic Control Unit).
The ECU 20 includes an oil level OL from the oil level sensor 14, a water temperature sensor 15
A detection signal from various sensors such as a cooling water temperature THW from the ECU is input, the oil cutoff valve 11 is opened / closed by a control signal from the ECU 20, and a warning light 21 is turned on. The opening and closing of the fuel cutoff valve 7 is controlled in conjunction with ON / OFF of an ignition switch (not shown).
The high-pressure fuel cylinder 5 and the fuel pipe 6 are connected via an on-off valve 5a attached to a fuel supply port of the high-pressure fuel cylinder 5, and this on-off valve 5a is used when the high-pressure fuel cylinder 5 is replaced. It is opened and closed.

The ECU 20 is configured as a logical operation circuit mainly including a CPU as a well-known central processing unit, a ROM storing control programs, a RAM storing various data, a B / U (backup) RAM, and the like. Are connected via a bus to an input port for inputting the detection signal of, and an output port for outputting control signals to various actuators.

Next, an EC used in a gas fuel supply device for an internal combustion engine according to an embodiment of the present invention will be described.
The processing procedure of the oil mixing control in the CPU in U20 will be described based on the flowchart of FIG. In addition,
This oil mixing control routine is repeatedly executed by the CPU in the ECU 20 at predetermined time intervals simultaneously with the turning on of the ignition switch.

In FIG. 2, first, in step S101,
Then, the cooling water temperature THW detected by the water temperature sensor 15 is read. Next, the process proceeds to step S102,
It is determined whether the cooling water temperature THW read in 101 exceeds 70 ° C. When the determination condition of step S102 is not satisfied and the cooling water temperature THW is 70 ° C. or lower, the process proceeds to step S103, where the oil cutoff valve 11 mounted in the middle of the oil supply pipe 9 is kept in the closed state.
Steps 1 to S103 are repeatedly executed.

If the condition of step S102 is satisfied and the cooling water temperature THW exceeds 70 ° C., the process proceeds to step S104, where the oil cutoff valve 11 is opened, and the oil pumped from the oil pump 10 is supplied. The gas is mixed into the fuel pipe 6 from the nozzle 9a at the tip through the pipe 9. A check valve 12 is mounted on the oil supply pipe 9 downstream of the oil cutoff valve 11, so that even if the engine speed of the internal combustion engine 1 is low and the oil pressure is lower than the fuel pressure (fuel pressure), The fuel passes through the oil cutoff valve 11 and the oil pump 1
There is no backflow to the 0 side.

Here, the amount of oil mixed into the fuel in the fuel pipe 6 from the nozzle 9a at the tip of the fuel supply pipe 9 is adjusted to be about 0.1 to 0.2 [wt%] of the fuel weight. Have been. One of the reasons for mixing oil into the fuel when the cooling water temperature THW exceeds 70 ° C. is that if the oil temperature is high, the viscosity decreases, and the oil mixed into the fuel injected and supplied from the fuel injection valve 2. Is also good, the stagnation in the intake pipe 3 is small, and the amount of unburned HC (hydrocarbon) discharged even when flowing into the combustion chamber 4 in large quantities can be reduced. Another reason is that the cooling water temperature TH
If W exceeds 70 ° C., the exhaust gas purification catalyst 19 mounted downstream of the exhaust pipe 18 is activated, and even if oil is discharged as unburned HC, it can be purified by the exhaust gas purification catalyst 19.

Next, the routine proceeds to step S105, where the oil level sensor 14 for the oil lubricating the internal combustion engine 1 is used.
It is determined whether the oil level OL is OK (appropriate amount). If the determination condition of step S105 is not satisfied and the oil level OL is consumed until the oil level becomes less than the predetermined amount, the process proceeds to step S106, and the oil cutoff valve 1
1 is closed. Next, the process proceeds to step S107, and after the warning lamp 21 is turned on, the process proceeds to step S108. On the other hand, the determination condition of step S105 is satisfied,
If the oil level OL is an appropriate amount, the process directly proceeds to step S108.

In step S108, it is determined whether or not the ignition switch has been turned off. Step S1
If the determination condition of 08 is not satisfied and the ignition switch remains ON, the process returns to step S101, and the same processing is repeatedly executed. On the other hand, step S108
Is satisfied, and the ignition switch is turned off.
Then, the process proceeds to step S109, where the oil cutoff valve 1
After the valve 1 is closed, the routine ends.

FIG. 3 is a graph showing the amount of wear of the seat portion [μ] using the oil mixing amount [wt%] in the gas fuel supply device for an internal combustion engine according to one embodiment of the present invention as a parameter.
m], oil consumption [%], and tail pipe HC emission [ppm] in a transition diagram.

As shown in FIG. 3, by mixing oil into the fuel, the amount of wear of the seat portion (not shown) of the fuel injection valve 2 which is a movable portion for adjusting the fuel is significantly reduced. It is understood that it is done. That is, the oil mixing amount is 0.
When it is 1 [wt%] or more, the wear amount [μm] of the seat portion becomes substantially constant. At this time, since the oil consumption [%] is suppressed to about 10 [%] during the maintenance interval, it is not necessary to particularly increase the capacity of the oil pan 1a of the internal combustion engine 1. Further, the tail pipe HC emission [ppm] on the outlet side of the exhaust gas purifying catalyst 19 mounted on the downstream side of the exhaust pipe 18 of the internal combustion engine 1 is also:
When the exhaust gas purifying catalyst 19 is activated, the amount does not increase unless the oil mixing amount exceeds 1.0 [wt%].

Thus, the wear of the seat portion of the fuel injection valve 2 is prevented without deteriorating the operation performance of the internal combustion engine 1, and the wear of the seat portion and the sliding portion of the intake valve 16 and the exhaust valve 17 are also prevented. You. That is, the fuel injection valve 2, the intake valve 16
In addition, it is possible to prevent poor sealing due to abrasion of the seat portion and the sliding portion of the exhaust valve 17 and a decrease in the metering accuracy of supplied fuel.

As described above, the gas fuel supply device for an internal combustion engine according to the present embodiment includes a fuel injection valve 2 for injecting fuel (gas fuel) to the internal combustion engine 1 through the fuel pipe 6, and a fuel injection valve 2 for the fuel injection valve 2. An oil supply pipe 9 is provided to connect between an upstream fuel pipe 6 and an oil pump 10 for pumping oil for lubricating the internal combustion engine 1, and the oil is mixed into the fuel in the fuel pipe 6 via the oil supply pipe 9. Things. That is, the oil from the oil supply pipe 9 is mixed with the non-lubricating fuel in the fuel pipe 6 and lubricity is imparted to the seat portion and the sliding portion of the fuel injection valve 2, thereby preventing wear and durability. Is improved. At the same time, the intake valve 16 and the exhaust valve 17 on the downstream side of the fuel injection valve 2
The wear of the seat portion and the sliding portion can also be suppressed.

In the gas fuel supply device for an internal combustion engine according to the present embodiment, the amount of mixed oil [wt%] is set to 0.1 to 0.2 [wt%] of the amount of fuel injected and supplied from the fuel injection valve 2. Is what you do. In other words, the oil mixing amount [wt%] is set to be about 0.1 to 0.2 [wt%] of the fuel amount in order to impart lubricity to the seat portion and the sliding portion of the fuel injection valve 2, so that the oil amount is reduced. Reduce consumption by about 1 during the maintenance interval
It can be suppressed to about 0%. Therefore, a desired effect can be obtained without having to increase the capacity of the oil pan 1a of the internal combustion engine 1.

The gas fuel supply device for an internal combustion engine according to the present embodiment has an oil cutoff valve 11 that is controlled in accordance with the cooling water temperature THW of the internal combustion engine 1 in the middle of the oil supply pipe 9 so that the cooling water temperature THW can be controlled. When the temperature exceeds 70 ° C, the oil shutoff valve 11
Is opened to mix oil into fuel.
That is, when the operation state is such that the cooling water temperature THW of the internal combustion engine 1 exceeds 70 ° C., the exhaust gas purification catalyst 19 mounted on the downstream side of the exhaust pipe 18 is activated. Therefore, even if the oil shut-off valve 11 is opened and oil is mixed into the fuel, and this oil is discharged to the exhaust pipe 18 side as unburned HC after combustion in the internal combustion engine 1, the exhaust gas purifying catalyst may be used. At 19, it can be purified.

In the above embodiment, the nozzle 9a of the fuel supply pipe 9 is connected in the middle of the fuel pipe 6. However, the present invention is not limited to this. It is sufficient that the oil from the fuel supply pipe 9 is uniformly mixed with the fuel in the fuel pipe 6, and the fuel pipe 6 and the fuel injection valve 2
The nozzle 9a of the oil supply pipe 9 can also be connected to the connection portion with.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an entire configuration of a gas fuel supply device for an internal combustion engine according to an example of an embodiment of the present invention.

FIG. 2 is an ECU used in a gas fuel supply device for an internal combustion engine according to an embodiment of the present invention.
It is a flowchart which shows the processing procedure of oil mixing control in CPU inside.

FIG. 3 is a graph showing a change in a seat wear amount, an oil consumption amount, and a transition state of a tail pipe HC emission using an oil mixing amount as a parameter in a gas fuel supply device for an internal combustion engine according to an embodiment of the present invention. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Fuel injection valve 6 Fuel pipe 9 Oil supply pipe 10 Oil pump 11 Oil cutoff valve 20 ECU (Electronic control unit)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Motomasa Iizuka 14 Iwatani, Shimowasakucho, Nishio City, Aichi Prefecture Inside the Japan Automobile Parts Research Institute Co., Ltd. (72) Inventor Yoshinao Wakamatsu 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Inside of DENSO Corporation

Claims (3)

[Claims] A fuel injection valve for injecting gaseous fuel into the internal combustion engine via a fuel pipe; and an oil pump for pumping oil for lubricating the fuel pipe upstream of the fuel injection valve and the internal combustion engine. An oil supply pipe for connecting the oil and the oil to the gas fuel in the fuel pipe via the oil supply pipe. 2. The mixing amount of the oil is 0.1 to 0.2 wt% of the gas fuel amount injected and supplied from the fuel injection valve.
%: Weight percent].
3. A gas fuel supply device for an internal combustion engine according to claim 1. 3. An oil shutoff valve controlled in accordance with a cooling water temperature of the internal combustion engine in the middle of the oil supply pipe, and when the cooling water temperature exceeds 70 ° C., the oil shutoff valve is opened. 3. The gas fuel supply device for an internal combustion engine according to claim 1, wherein the oil is mixed with the gas fuel.