JPH11141357A - Exhaust brake device of fuel gas engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the temporary overlean state of an air fuel ratio after the release of an exhaust brake and to solve the deterioration of the drivability of a vehicle, the engine stall or the like in an exhaust brake device where a shutter valve of an exhaust path is closed during the operation of the exhaust brake of a LPG engine, so that the supply of the fuel to an inlet path is stopped and only the intake air is supplied to the engine, and the engine is operated as a compressor to obtain the braking force. SOLUTION: The fuel gas is forcibly supplied to an intake path of an engine from a secondary fuel supply device of a system different from that of an ordinary main fuel supply device during the passage of the predetermined times t1, t2 from a time when the operation of an exhaust brake is released, whereby the overlean of an air/fuel ratio caused by the delay of the supply of the fuel from the main fuel supply device in an initial period of the operation releasing state of the exhaust brake, can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust brake device for a gas fuel type engine, and more particularly to a technical field related to a device for eliminating a delay in fuel supply when the exhaust brake is released.

[0002]

2. Description of the Related Art Conventionally, as this kind of gas fuel type engine, an LPG engine using LPG (liquefied petroleum gas) as a fuel is well known, and is generally mounted on a commercial vehicle such as a taxi. In this LPG engine, liquefied LPG supplied from an LPG container is gasified by a regulator (vaporizer), and this LPG is supplied to an intake passage of the engine, mixed with intake air by a mixer (mixer), and the air-fuel mixture is mixed with the engine. Is taken into a cylinder and burned. .

In a vehicle equipped with such an LPG engine, an exhaust shutter valve for opening and closing an exhaust passage of the engine is provided as a braking system, and a driver of the vehicle operates an exhaust brake switch to obtain a brake state. At this time, the exhaust shutter valve is closed, the fuel supply is stopped as described above, and only the intake air is supplied to the combustion chamber of the engine, so that the engine itself works as a compressor, and the loss for air compression in the engine is reduced. Exhaust brake devices that obtain the braking force as a braking force are known.

[0004] In this exhaust brake device, in order to draw intake air into the combustion chamber of the engine during operation, the throttle valve is kept fully open or an air bypass passage for bypassing the throttle valve and the air bypass passage are provided. A bypass valve for opening and closing the bypass passage is provided, and the bypass valve is opened.

[0005]

However, when the fuel supply is stopped and only the intake air is sucked into the engine during the operation of the exhaust brake, there is no gas fuel in the intake passage downstream of the mixer. Therefore, when the operation of the exhaust brake is subsequently released, the gas fuel from the mixer is not immediately supplied to the combustion chamber of the engine, and the air-fuel ratio becomes over-lean due to the delay in the supply of the gas fuel. There has been a problem that the drivability of the vehicle deteriorates, and in the worst case, the engine stalls.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the fuel control system of a gas-fueled engine as described above, so that the engine is temporarily emptied after the release of the engine exhaust brake. It is an object of the present invention to prevent the fuel ratio from falling into an over-lean state, and to reduce the drivability of the vehicle, the engine stall, and the like.

[0007]

In order to achieve the above object, according to the present invention, when the operation of the exhaust brake is released, the gas fuel is increased in the intake passage of the engine for a predetermined time from that time. The air-fuel ratio during the supply was over-lean.

[0008] Specifically, as shown in FIG.
According to the invention, the fuel supply means 26 for supplying gaseous fuel to the intake passage 8 of the engine 1, the exhaust shutter valve 22 for opening and closing the exhaust passage 18 of the engine 1, and the exhaust shutter valve 2
2 is closed, the fuel supply by the fuel supply means 26 is stopped, and the exhaust brake means 57 for supplying only the intake air to the combustion chamber 6 of the engine 1, and the operation of the exhaust brake by the exhaust brake means 57 is released. The fuel supply means 2 until the set time elapses.
6 and a fuel supply control means 58 for increasing the amount of gas fuel.

According to this configuration, the exhaust brake means 57
, The fuel supply by the fuel supply means 26 is stopped, and only the intake air is supplied to the combustion chamber 6 of the engine 1, and at the same time, the exhaust shutter valve 22 of the exhaust passage 18 is closed. In this state, the engine 1 becomes a compressor that compresses intake air, and the braking force of the engine 1 is obtained.

Thereafter, when the operation of the exhaust brake is released, the exhaust shutter valve 22 is opened, and the supply of gaseous fuel by the fuel supply means 26 is resumed. Until the fuel supply control means 58 is operated, the amount of gas fuel by the fuel supply means 26 is increased. For this reason, even if there is no gas fuel in the intake passage 8 in the initial state of the release of the operation of the exhaust brake, the increased amount of gas fuel from the fuel supply means 26 is quickly supplied to the combustion chamber 6 of the engine 1, It is possible to prevent the air-fuel ratio from being over-lean due to the supply delay, and to reliably reduce the drivability of the vehicle and the engine stall due to the sluggish acceleration of the engine 1.

In the second aspect of the present invention, the fuel supply control means 58 is configured to increase the set time as the engine speed at the time of releasing the operation of the exhaust brake decreases. In this way, even if a large delay in fuel supply occurs when the exhaust brake is released due to a decrease in the amount of intake air due to a decrease in the engine speed, a large amount of gas fuel can be supplied to compensate for it, and a change in the engine speed can be achieved. In spite of this, it is possible to stably prevent deterioration of drivability and the like by maintaining an appropriate air-fuel ratio.

According to the third aspect of the present invention, the fuel supply means 26
Comprises a main fuel supply means 27 for supplying gaseous fuel during normal operation of the engine 1 and an auxiliary fuel supply means 40 for supplying gaseous fuel in a system separate from the main fuel supply means 27. By supplying gas fuel to the intake passage 8 of the engine 1 by the auxiliary fuel supply means 40,
It is configured to increase the amount of gas fuel. In this case, when the operation of the exhaust brake is released, the increased amount of gas fuel is supplied by the auxiliary fuel supply means 40 of a different system from the main fuel supply means 27 for supplying gas fuel during normal operation of the engine 1. Therefore, appropriate control of the increased fuel can be easily performed.

According to the fourth aspect of the present invention, the auxiliary fuel supply means is configured to supply gas fuel to the intake passage downstream of the gas fuel supply position of the main fuel supply means. Thus, when the operation of the exhaust brake is released, the gas fuel from the auxiliary fuel supply means 40 is supplied to the main fuel supply means 27.
And the gas fuel from the auxiliary fuel supply means 40 can effectively exert the effect of maintaining the air-fuel ratio appropriately.

According to the fifth aspect of the present invention, the main fuel supply means 27 supplies the gas fuel from the regulator 31 to the intake passage 8.
The auxiliary fuel supply means 40 injects the gas fuel at a higher pressure than the gas fuel of the main fuel supply means 27 into the intake passage 8 through the injector 42 in the regulator 31. Configure to supply. In this case, the gas fuel by the auxiliary fuel supply means 40 can be quickly supplied to the intake passage 8, and the same operation and effect as the invention of claim 4 can be obtained.

In the invention of claim 6, the injector 42 of the auxiliary fuel supply means 40 injects and supplies gaseous fuel to the intake passage 8 of the engine 1 when the engine 1 is started. By doing so, the injector 4 of the auxiliary fuel supply means 40
2 can be used also as an injector for supplying starting fuel for supplying the starting fuel for the engine 1, and the cost can be reduced by sharing parts.

According to the seventh aspect of the present invention, an air bypass passage 13 for supplying intake air by bypassing the throttle valve 11 of the intake passage 8 of the engine 1 and the air bypass passage 1
And an air bypass valve 14 for opening and closing the air bypass valve 3. The exhaust brake means 57 is configured to open the air bypass valve 14 when the exhaust brake is operated. Thus, when the exhaust brake operates, the intake air can be quickly supplied to the combustion chamber 6 of the engine 1 via the air bypass passage 13.

In the invention of claim 8, the gas fuel is LPG or CNG (compressed natural gas). Thus, the effect of optimizing the air-fuel ratio when the exhaust brake is released is effective.

[0018]

FIG. 7 shows an overall configuration of an embodiment of the present invention, wherein 1 is an LPG engine using LPG as fuel,
The engine 1 includes a cylinder block 3 having a cylinder 2, a cylinder head 4 assembled to the cylinder block 3, and a piston 5 reciprocally fitted into the cylinder 2. A space surrounded by the head 4 and the piston 5 is a combustion chamber 6. 4a is a cylinder head cover attached to the cylinder head 4.

Reference numeral 8 denotes an intake passage for supplying intake air to the combustion chamber 6 of the engine 1, and reference numeral 9 denotes an intake valve for opening and closing a downstream end of the intake passage 8. In the intake passage 8, in order from the upstream side,
An air cleaner 10 for filtering intake air, a throttle valve 11 for narrowing the intake passage 8, and a surge tank 12 are provided.

The air cleaner 10 and the throttle valve 11
The intake air is supplied to the intake passage 8 between the throttle valve 11 and
The upstream end of an air bypass passage 13 that supplies air to the engine 1 while bypassing the air passage is branched and connected.
The downstream end of 3 is connected to the intake passage 8 by the surge tank 12. An air bypass valve 14 that opens and closes the air bypass passage 13 is disposed in the air bypass passage 13.

The air bypass valve 14 has a valve body 14a for opening and closing the air bypass passage 13, and a diaphragm 14c connected to the valve body 14a and defining a pressure chamber 14b.
And a spring 14d disposed in the pressure chamber 14b and biasing the diaphragm 14c in the direction in which the valve element 14a closes. The pressure chamber 14b is connected via a pressure passage 16 to an air bypass solenoid valve 15 that connects the pressure chamber 14b to a vacuum pump (not shown) driven by the engine 1 or the like or switches to open to the atmosphere. When the pressure chamber 14b of the air bypass valve 14 is connected to the vacuum pump or opened to the atmosphere by the air bypass solenoid valve 15, and the pressure chamber 14b is opened to the atmosphere,
When the valve body 14a is closed by the urging force of the spring 14d, and the pressure chamber 14b is communicated with the vacuum pump, a negative pressure of the vacuum pump is introduced into the pressure chamber 14b.
The valve 14a is opened against the urging force of the spring 14d.

Reference numeral 18 denotes an exhaust passage for discharging exhaust gas from the combustion chamber 6 of the engine 1. Reference numeral 19 denotes an exhaust valve for opening and closing an upstream end of the exhaust passage 18. The exhaust passage 18 is provided with an exhaust gas in order from the upstream side. O ₂ sensor 2 for detecting oxygen concentration in gas
0 and an exhaust purification catalyst 21 are provided.

In the exhaust passage 18 between the O ₂ sensor 20 and the catalyst 21, an exhaust shutter valve 22 for opening and closing the exhaust passage 18 is provided. The exhaust shutter valve 22 also has basically the same structure as the air bypass valve 14, and includes a butterfly valve-type valve body 22a for opening and closing the exhaust passage 18, and a diaphragm connected to the valve body 22a and defining a pressure chamber 22b. 22c and a spring 22d disposed in the pressure chamber 22b and biasing the diaphragm 22c in a direction in which the valve body 22a opens. The pressure chamber 22b is connected via a pressure passage 24 to an exhaust brake solenoid valve 23 that switches the pressure chamber 22b to communicate with the vacuum pump or to open to the atmosphere. When the chamber 22b is communicated with the vacuum pump or opened to the atmosphere, and the pressure chamber 22b is opened to the atmosphere, the valve 22a is biased by the spring 22d.
Is opened (exhaust brake released state), when the pressure chamber 22b is communicated with the vacuum pump, a negative pressure is introduced into the pressure chamber 22b, and the valve body 2 is pressed against the urging force of the spring 22d.
2a is closed (exhaust brake state).

A fuel supply device 26 for supplying LPG (gas fuel) to the intake passage 8 of the engine 1 is provided. During normal operation of the engine 1 (other than during start-up and when the exhaust brake is released), the fuel supply device 26
A main fuel supply device 27 for supplying G, and a main fuel supply device 2 for supplying LPG when starting the engine 1 and releasing the exhaust brake.
7 and an auxiliary fuel supply device 40 that supplies the fuel in a separate system.

The main fuel supply device 27 has a mixer 28 (mixer) disposed in the intake passage 8 between the connection portion at the upstream end of the air bypass passage 13 and the throttle valve 11. The mixer 28 is provided with a venturi section 2 for narrowing the intake passage 8.
The LPG 9 from the regulator 31 described later is sucked into the intake passage 8 and mixed with the intake air by the venturi negative pressure in the intake passage 8 generated in the venturi section 29.

A regulator 31 (vaporizer) is connected to the mixer 28 via a main fuel passage 30. The regulator 31 adjusts the evaporation amount of the liquefied LPG. That is, the regulator 31 is connected via a liquid fuel passage 32 to an LPG container (not shown) that stores pressurized and liquefied LPG (fuel gas), and pressurizes the liquid LPG at a high pressure (for example, 29 kPa) higher than the atmospheric pressure. )
The high-pressure chamber 33 for adjusting the pressure to a gaseous LPG, and the low-pressure chamber 3 for adjusting the LPG to a low pressure substantially equal to atmospheric pressure (0 Pa).
The low-pressure chamber 34 is connected to the upstream end of the main fuel passage 30. The liquefied LPG supplied from the LPG container is vaporized and gasified to convert the liquefied LPG into a high-pressure chamber 33 of the regulator 31.
And the low pressure chamber 34 sequentially reduces the pressure, and supplies this LPG to the mixer 28 via the main fuel passage 30.

In the middle of the main fuel passage 30, a fuel cut valve 35 for opening and closing the main fuel passage 30 to supply or stop the supply of LPG to the mixer 28 in the intake passage 8 is arranged. The fuel cut valve 35 is the same as the exhaust shutter valve 22, and has a valve body 35a for opening and closing the main fuel passage 30 and a pressure chamber 35 connected to the valve body 35a.
b, and a spring 35d disposed in the pressure chamber 35b and biasing the diaphragm 35c in a direction in which the valve 35a opens. Pressure chamber 3
5b is connected via a pressure passage 37 to a fuel cut solenoid valve 36 that switches the pressure chamber 35b to communicate with the vacuum pump or to open to the atmosphere. The fuel cut solenoid valve 36 controls the pressure chamber 35b. Is connected to a vacuum pump or opened to the atmosphere, and the pressure chamber 35b is opened to the atmosphere, the valve body 35a is opened by the urging force of the spring 35d (fuel supply state) while the pressure chamber 35b is opened.
When b is communicated with the vacuum pump, a negative pressure is introduced into the pressure chamber 35b to close the valve body 35a against the urging force of the spring 35d to bring the fuel into a cut-off state.

The main fuel supply device 27 has two correction fuel passages 44 for controlling the air-fuel ratio of the intake air to the engine 1. The upstream ends of the correction fuel passages 44 are respectively connected to the main fuel passage 30 between the low pressure chamber 34 of the regulator 31 and the fuel cut valve 35.
The downstream ends of the correction fuel passages 44, 44 are assembled together and connected to the venturi section 29 of the mixer 28. Near the downstream ends of the correction fuel passages 44 (upstream of the collecting portion), normally closed (normally OFF) feedback solenoid valves 45, 45 for variably adjusting the LPG flow rates in the correction fuel passages 44, 44, respectively are provided. The two feedback solenoid valves 4 are provided.
The fuel supply amount to the intake passage 8 of the engine 1 is corrected and controlled by a system different from the main fuel passage 30 by simultaneously controlling the opening of the feedback solenoid valves 45 and 45, and the feedback solenoid valves 45 and 45 are turned off. In this state, the correction fuel passages 44 and 44 are closed to set the fuel correction amount to the intake passage 8 to “0”, while the feedback solenoid valve 4
5 and 45 are turned on, the correction fuel passage 4
4 and 44 are opened and the opening is variably controlled (or fixed at a set opening) to control the air-fuel ratio of the intake air to the engine 1.

On the other hand, the auxiliary fuel supply device 40 has an auxiliary fuel passage 41 whose upstream end is connected to the high pressure chamber 33 of the regulator 31. The downstream end of the auxiliary fuel passage 41 is connected to the surge tank 12 and the throttle valve. 11 and is open to the intake passage 8. Near the upstream end of the auxiliary fuel passage 41, a normally closed (always OFF) fuel injection injector 42 that allows a constant flow of LPG to pass in a valve open state is provided. The injector 42 supplies LPG to the intake passage 8 of the engine 1 when the engine 1 is started. By opening the injector 42, the intake air is supplied from the main fuel passage 30 of the main fuel supply device 27 through the mixer 28. In a system different from the LPG supplied to the passage 8, the high pressure chamber 33 of the regulator 31 is provided to the intake passage 8 downstream of the fuel supply position (position of the mixer 28) by the main fuel supply device 27.
The internal high pressure LPG is supplied via the auxiliary fuel passage 41.

That is, the main fuel supply device 27 is configured to suck the LPG (gas fuel) from the low pressure chamber 34 of the regulator 31 by the Venturi negative pressure in the mixer 28 in the intake passage 8. The regulator 40 is configured to inject and supply the LPG of the high-pressure chamber 33 having a higher pressure than the LPG of the main fuel supply device 27 to the intake passage 8 by opening the injector 42.

The above-mentioned air bypass solenoid valve 15, exhaust brake solenoid valve 23, fuel cut solenoid valve 3
6. The operation of the injector 42 and each feedback solenoid valve 45 is controlled by the control unit 50. This control unit 50
ON / OF at least by the operation of the vehicle driver
F, an exhaust brake switch 51 that is switched to F, an idle switch 52 that turns on by detecting a fully closed state of the throttle valve 11 in which an accelerator pedal (not shown) of the vehicle is fully returned, and a clutch pedal (not shown) of the vehicle. The clutch switch 53 is turned on when the clutch is not depressed (the connected state), the neutral switch 54 is turned on when the on-vehicle transmission (not shown) is in the non-neutral state, and according to the engine speed. ON / OFF
Each signal of the operating engine rotation switch 55 is input. The engine rotation switch 55 is
For example, when the engine speed is 1250 rpm (set speed)
When it rises above, it turns ON and the idle switch 52
When the switch is ON, the input / output units (J) and (T) described later are short-circuited.

Specifically, as shown in FIG. 3, the control unit 50 has three input units (Q), (D), and (J).
And four output units (U), (P), (I), and (T). An exhaust brake switch 51, a neutral switch 54, and a clutch switch 53 are connected to the input unit (J) via a diode d. They are connected in series. Further, the idle switch 52 is connected in series between the input units (Q) and (D), and is turned on / off of the idle switch 52.
The state is determined by a signal to the input section (Q). on the other hand,
An air bypass solenoid valve 15 and an exhaust brake solenoid valve 23 are connected in parallel to the output section (T).
An injector 42 is connected to the output unit (U), a fuel cut solenoid valve 36 is connected to the output unit (P), and two feedback solenoid valves 45, 45 are connected in parallel to the output unit (I). It is connected to the. The air bypass solenoid valve 15 and the exhaust brake solenoid valve 23 are directly connected to the injector 4.
2. The fuel cut solenoid valve 36 and the two feedback solenoid valves 45, 45
6 are connected to an in-vehicle power supply (not shown).
In FIG. 3, reference numeral 47 denotes a display lamp which is turned on by the ON operation of the exhaust brake switch 51 to display the operating state of the exhaust brake.

In the control unit 50,
The operation performed for the exhaust brake control during the operation of the engine 1 will be described with reference to FIGS. First, in step S1 in FIG. 4, the fuel cut valve 35 is turned off (open operation without fuel cut) by the fuel cut solenoid valve 36, and in step S2, the feedback solenoid valves 45, 45 are turned on (air-fuel ratio control or setting). In step S3, the air bypass valve 14 is turned off by the air bypass solenoid valve 15 (close operation of the air bypass passage 13), and in step S4, the exhaust shutter valve 2 is released by the exhaust brake solenoid valve 23.
2 is turned off (opening the exhaust passage 18). The above steps S1 to S4 are processing for releasing the operation of the exhaust brake.

After step S4, the process proceeds to step S5, where the exhaust brake switch 51 is operated by the vehicle driver.
Is determined to be in the ON state. When this determination is NO for "exhaust brake switch OFF", the process returns to step S1. When the determination in step S5 is "YES" of "exhaust brake switch ON", the process proceeds to step S6, and it is determined whether the neutral switch 54 is ON according to the non-neutral state of the vehicle-mounted transmission.
If this determination is NO for "neutral switch OFF", the process returns to step S1. If the determination in step S6 is YES for "neutral switch ON", the process proceeds to step S7, where it is determined whether or not the clutch switch 53 is ON by returning the clutch pedal, and the determination is "clutch switch OFF". If NO, the process returns to step S1. If the determination in step S7 is YES for "clutch switch ON", step S8
To determine whether or not the engine rotation switch 55 is in the ON state (the engine rotation speed is equal to or higher than the set rotation speed).
If "F" is NO, the process returns to step S1. Step S
If the determination in step 8 is YES for "engine rotation switch ON", the process proceeds to step S9 to determine whether or not the idle switch 52 is in the ON state by the fully closing operation of the throttle valve 11 (return operation of the accelerator pedal). When this determination is NO for "idle switch OFF", the process returns to step S1.

When the determination in step S9 is "YES" of "idle switch ON", the process proceeds to steps S10 to S13, which are processing steps for operating the exhaust brake. That is, in the first step S10, the fuel cut valve 35 is turned on by the fuel cut solenoid valve 36 (close operation for performing fuel cut), and in the next step S11, the feedback solenoid valves 45 are turned off (the correction fuel passage 44 is closed). (Close operation), and the air bypass valve 14 is turned on by the air bypass solenoid valve 15 in step S12.
The operation (opening operation of the air bypass passage 13) is performed, and in step S13, the exhaust shutter valve 22 is turned on by the exhaust brake solenoid valve 23 (the closing operation of the exhaust passage 18).

After step S13, the process proceeds to steps S14 to S18 shown in FIG. 5 to perform processing for releasing the exhaust brake. That is, steps S14 to S18 are the same as steps S5 to S9, respectively.
Then, it is determined whether or not the exhaust brake switch 51 is ON. This judgment is "exhaust brake switch OF
If the answer is "F", the injector 42 is turned on for the first set time t1 in step S19, and then the process returns to step S1 shown in FIG. When the determination in step S14 is YES for "exhaust brake switch ON", the process proceeds to step S15 to determine whether the neutral switch 54 is in the ON state. If this determination is NO for "neutral switch OFF", the process returns to step S1 via step S19. If the determination in step S15 is YES for "neutral switch ON", the process proceeds to step S16, in which the clutch switch 53 is turned on.
It is determined whether the vehicle is in the state. If the determination is NO for "clutch switch OFF", the process returns to step S1 via step S19. If the determination in step S16 is YES for "clutch switch ON", step S1
The program proceeds to 7 to determine whether or not the engine rotation switch 55 is ON. If the determination is NO for "engine rotation switch OFF", the process returns to step S1 via step S19. If the determination in step S17 is YES for "engine rotation switch ON", the process proceeds to step S18, where it is determined whether or not the idle switch 52 is in the ON state due to the fully closing operation of the throttle valve 11. When the determination is "OFF", in step S20, the injector 42 is turned ON for the second set time t2 longer than the first set time t1, and then the process returns to step S1. In addition, the above step S
If the determination at 18 is "idle switch ON", the process returns to step S10 shown in FIG.

That is, the opening / closing operation of the exhaust shutter valve 22 by the exhaust brake solenoid valve 23, the opening / closing operation of the fuel cut valve 35 by the fuel cut solenoid valve 36,
ON / OFF of feedback solenoid valves 45, 45
The operation and the ON / OFF operation of the injector 42 will be described in detail. As shown in Table 1 and FIG.
When all of the exhaust brake solenoid valve 23, the fuel cut solenoid valve 36, and the feedback solenoid valves 45, 45 are in the ON state, the exhaust brake switch 51, the neutral switch 54, the clutch switch 53, the engine rotation switch 55, and the idle switch 52 are all ON. ON operation when one of them is OFF
F operation is performed.

On the other hand, the injector 42 changes from the state in which the exhaust brake switch 51, the neutral switch 54, the clutch switch 53, the engine rotation switch 55, and the idle switch 52 are all ON to the state in which the engine rotation switch 55 is OFF. Or when the exhaust brake switch 51, the neutral switch 54, or the clutch switch 53 changes to the OFF state, for a first set time t1 from the change.
When the idle switch 52 changes to the OFF state, the idle switch 52 is turned ON and opened for a second set time t2 (> t1) longer than the first set time from the time of the change. The injector 42 is turned off when the set times t1 and t2 elapse or when the engine rotation switch 55, the exhaust brake switch 51, the clutch switch 53, the neutral switch 54, and the idle switch 52 are all turned on. It operates and closes the valve.

[0039]

[Table 1]

FIG. 6 exemplifies first and second set times t1 and t2 for setting the injector 42 to the valve open state. For example, the first set time t1 is as shown in FIG. 6 (a). T1 when the engine speed is 0 to 750 rpm
= 1.5 seconds constant, and the engine speed is 750-750
In the range of 1500 rpm, t1 = 1.5 seconds to t1 = 0
Up to the second, proportionally decreasing with increasing engine speed,
When the engine speed exceeds 1500 rpm, t1 is set to 0 seconds. On the other hand, the second set time t2 is
As shown in FIG. 6B, the engine speed is 0 to 750r.
When the engine speed is in the range of 750 to 1500 rpm, t2 = 3.0 seconds.
It is set so as to decrease in proportion to the increase in the engine speed from 0 seconds to t2 = 0 seconds, and to become t2 = 0 seconds when the engine speed exceeds 1500 rpm.

In this embodiment, the exhaust shutter valve 22 is closed and the fuel cut valve 35 and the feedback solenoid valves 45, 45 are closed during the operation of the exhaust brake in steps S10 to S13 of the routine shown in FIG. And an exhaust brake in which the supply of LPG by the auxiliary fuel supply devices 27 and 40 is stopped, and the air bypass valve 14 is opened to supply only intake air to the combustion chamber 6 of the engine 1 via the air bypass passage 13. Means 57 is constituted.

Steps S14 to S20 shown in FIG.
Accordingly, when the operation of the exhaust brake by the exhaust brake means 57 is released, the injector 4 of the auxiliary fuel supply device 40 is maintained until the set times t1 and t2 elapse.
2, the fuel supply control means 58 is configured to supply the LPG from the auxiliary fuel supply device 40 in addition to the main fuel supply device 27 and increase the LPG by the entire fuel supply device 26. I have. The fuel supply control means 58 determines that the engine speed is 750 to 15
In the range of 00 rpm, the set times t1 and t2 are set longer according to the engine speed as the engine speed decreases.

Next, the operation of the above embodiment will be described. When the engine 1 is operating, the air bypass valve 14 is closed, and the intake air is supplied to the engine 1 through the intake passage 8. The fuel cut valve 35 is opened, and the LPG in the low-pressure chamber 34 of the regulator 31 is sucked into the intake passage 8 through the main fuel passage 30 by the Venturi negative pressure of the mixer 28, and is mixed with the intake air by the mixer 28. After that, it is supplied to the combustion chamber 6 of the engine 1. Also, the feedback solenoid valves 45, 45 are in the ON state,
Due to the ON operation of the feedback solenoid valves 45, 45, a part of the fuel in the main fuel passage 30 is used as correction fuel through the correction fuel passages 44, 44, and the mixer 2 in the intake passage 8 is controlled.
In this way, the air-fuel ratio to the engine 1 is appropriately controlled. Further, the exhaust shutter valve 22 is opened.

In this state, when the exhaust brake switch 51 is turned ON by the vehicle driver,
The on-vehicle transmission is in a non-neutral state, the neutral switch 54 is in the ON state, the clutch is ON, the clutch switch 53 is in the ON state, and the engine speed is, for example, 1250 rpm (set speed) or more, and the engine rotation switch 55 is in the ON state. If all of the five conditions that the throttle valve 11 is fully closed and the idle switch 52 is in the ON state are achieved, the exhaust brake is activated (if any one of the five conditions is deviated, the exhaust brake is activated). Not activated). When the above five conditions are satisfied, the feedback solenoid valves 45, 45
Is switched from the ON state (air-fuel ratio control state) to the OFF state (closed state), and the air-fuel ratio control by the feedback solenoid valves 45 stops.

With the operation of the exhaust brake,
The fuel cut valve 35 is closed, and the supply of LPG by the main fuel supply device 27 is cut. Further, the air bypass valve 14 is opened, and the intake air is supplied to the combustion chamber 6 of the engine 1 by bypassing the closed throttle valve 11 by the air bypass passage 13, and further, the exhaust shutter valve 22 is closed and the exhaust passage 18 is closed. Is done. In this state, since only the intake air is supplied to the combustion chamber 6 of the engine 1, the engine 1 becomes a compressor that compresses the intake air, and the braking force of the vehicle by the engine 1 is obtained.

At this time, an air bypass passage 13 for bypassing the throttle valve 11 and an air bypass valve 14 for opening and closing the air bypass passage 13 are provided, and the air bypass valve 14 is opened with the operation of the exhaust brake. So
When the exhaust brake is operated, the intake air can be quickly supplied to the combustion chamber 6 of the engine 1 via the air bypass passage 13.

Thereafter, if any one of the above conditions is deviated, the operation of the exhaust brake is released and returns to the initial state, the exhaust shutter valve 22 opens, the air bypass valve 14 closes, and the fuel cut valve 35 closes. Open and the supply of LPG by the main fuel supply device 27 is restarted. Further, the feedback solenoid valves 44, 44 are turned on, and the air-fuel ratio control is performed. At that time, the injector 42 of the sub fuel supply device 40 opens in parallel with the supply of LPG by the main fuel supply device 27 until the set times t1 and t2 elapse from the release of the operation of the exhaust brake,
From the high pressure chamber 33 of the regulator 31, the main fuel supply device 2
The LPG having a higher pressure than the LPG of the low pressure chamber 34 of the regulator 31 by the pressure regulator 7 is supplied to the intake passage 8. Specifically, the set times t1 and t2 are different depending on the released state of the above five conditions 1 to 5, and the engine speed is, for example, 85
0 rpm or less and the engine speed switch 55
FF state (release of condition), OFF operation of exhaust brake switch 51 (release of condition), OFF state of neutral switch 54 (release of condition), or OFF state of clutch switch 53 (release of condition)
Is established, the first set time t1 is selected. On the other hand, when the idle state of the idle switch 52 (the release of the condition) is established, the second set time t2 longer than the first set time t1 is selected. You.

For this reason, at the beginning of the release state of the exhaust brake, the LP by the main fuel supply device 27 is
Even if there is no G, the high-pressure LPG due to the opening of the injector 42 of the auxiliary fuel supply device 40 will be quickly supplied to the combustion chamber 6 of the engine 1 through the intake passage 8, and the LPG generated by the main fuel supply device 27 An over-lean of the air-fuel ratio due to a supply delay can be avoided, and deterioration of the drivability of the vehicle and engine stall due to the slowness of the acceleration of the engine 1 can be reliably solved.

In this case, the LPG by the auxiliary fuel supply device 40 is equal to the LPG by the mixer 28 of the main fuel supply device 27.
Since the LPG is supplied to the intake passage 8 on the downstream side of the G supply position, the LPG from the auxiliary fuel supply device 40 can be supplied to the combustion chamber 6 of the engine 1 before the LPG from the main fuel supply device 27. Moreover, the main fuel supply device 27 sucks the LPG from the regulator 31 by the negative pressure in the intake passage 8, while the sub fuel supply device 40 draws the LPG from the regulator 31.
Since the high-pressure LPG having a high internal pressure is injected and supplied to the intake passage 8, the LPG of the auxiliary fuel supply device 40 is quickly supplied to the intake passage 8.
To the combustion chamber 6 of the engine 1. Thus, when the operation of the exhaust brake is released, the auxiliary fuel supply device 4
The effect of maintaining the air-fuel ratio properly by the LPG from 0 can be effectively exhibited.

The set times t1 and t2 during which the injector 42 opens when the exhaust brake is released are of two types, each of which has an engine speed of 750 to 150, for example.
In a rotation range of 0 rpm, the engine speed changes according to the engine speed so that the lower the engine speed becomes, the longer the set time becomes. Therefore, even if the intake air amount decreases due to the decrease in the engine speed, the Since the valve opening time of the valve 42 becomes longer, a large amount of LPG can be supplied, the air-fuel ratio can be appropriately maintained irrespective of the change in the engine speed, and the drivability of the vehicle can be stably prevented from deteriorating.

Further, since the injector 42 supplies the LPG of the high-pressure chamber 33 of the regulator 31 to the intake passage 8 of the engine 1 in the same manner as described above when the engine 1 is started, the injector 42 is set when the operation of the exhaust brake is released. Injector 4 for supplying LPG for times t1 and t2
2 can be used also as an injector for supplying the starting LPG of the engine 1, and the cost can be reduced by sharing parts.

In the above embodiment, the set times t1 and t2 for opening the valve of the injector 42 are set to be longer as the engine speed becomes lower, by limiting the engine speed to the rotation range where the engine speed is 750 to 1500 rpm. Although it is changed according to the engine speed, the set times t1 and t2 can be similarly changed so as to be longer as the engine speed becomes lower in all engine speed ranges.

In the above-described embodiment, the injector 42 having a constant LPG flow rate is used. However, an injector with a variable flow rate adjustment is provided, and the injection amount of the increased LPG is increased by opening the valve so that the engine speed becomes lower. It may be set variably so that

In the above embodiment, the LPG from the auxiliary fuel supply device 40 is directly injected and supplied to the intake passage 8 of the engine 1.
The fuel may be supplied to the first low-pressure chamber 34 or the main fuel passage 30, or may be supplied to the intake passage 8 of the engine 1.

Further, in the above embodiment, the LPG is injected and supplied from the auxiliary fuel supply device 40 of a different system from the main fuel supply device 27. However, the fuel supply device 26 comprises only the main fuel supply device 27, When the operation of the exhaust brake is released, LPG may be supplied from the main fuel supply device 27 in an increased amount, and the supply amount may be controlled. However, in terms of facilitating the control of the supply amount of the increased LPG, it is preferable to supply the LPG from the auxiliary fuel supply device 40 as in the above embodiment.

The present invention also relates to the LP as in the above embodiment.
Not only the G engine 1 but also other gases (for example, CNG
It goes without saying that the present invention can be applied to any gas-fueled engine that uses the same as a fuel.

[0057]

As described above, according to the first aspect of the present invention, the shutter valve of the exhaust passage is closed and the supply of gaseous fuel to the intake passage by the fuel supply means is stopped during the operation of the exhaust brake of the engine. In an exhaust brake system in which only intake air is supplied to the engine and the engine is operated as a compressor to obtain a braking force, when the operation of the exhaust brake is released, the time from the time until the set time elapses By increasing the amount of gaseous fuel supplied by the fuel supply means to the intake passage of the engine, the gaseous fuel is quickly supplied from the fuel supply means to the combustion chamber of the engine in a state where the exhaust brake is released, so that the normal amount of fuel is supplied. Over-lean of the air-fuel ratio due to the delay in the supply of gaseous fuel to Elimination of or engine stall or the like can be achieved.

According to the second aspect of the present invention, the time for supplying the increased amount of fuel by the fuel supply means is made variable so as to become longer as the engine speed decreases, so that the air-fuel ratio can be maintained regardless of the change in the engine speed. Deterioration of drivability and the like can be stably prevented while maintaining appropriateness.

According to the third aspect of the present invention, there is provided a main fuel supply means for supplying gaseous fuel during normal operation of the engine, and an auxiliary fuel supply means for supplying gaseous fuel in a system separate from the main fuel supply means. Gas fuel is supplied to the intake passage of the engine by the auxiliary fuel supply means to increase the amount of fuel when the exhaust brake is deactivated, so that appropriate control of the increased amount of gas fuel can be easily performed when the exhaust brake is deactivated. Can be.

According to the fourth aspect of the present invention, the auxiliary fuel supply means includes:
By supplying the gas fuel to the intake passage downstream of the gas fuel supply position by the main fuel supply means, the fuel from the sub fuel supply means is supplied by the main gas fuel supply means when the exhaust brake is deactivated. By supplying the fuel to the engine prior to the fuel, it is possible to effectively exert the effect of maintaining the appropriate air-fuel ratio when the exhaust brake operation is released.

According to the fifth aspect of the invention, the main fuel supply means is configured to suck the gas fuel from the regulator by the negative pressure in the intake passage, and the sub fuel supply means is configured to supply the high pressure gas in the regulator. The fuel is injected and supplied to the intake passage by the injector, so that the gas fuel by the auxiliary fuel supply means can be quickly supplied to the intake passage, and the effect of properly maintaining the air-fuel ratio when the exhaust brake operation is released is effectively exhibited. be able to.

According to the sixth aspect of the present invention, the injector of the auxiliary fuel supply means is used for starting the fuel by injecting the gas fuel into the intake passage of the engine when the engine is started. Also, it can be used also as a starting injector for supplying starting fuel for the engine, and the cost can be reduced by sharing parts.

According to the seventh aspect of the present invention, the air bypass valve is provided in the air bypass passage which bypasses the throttle valve in the intake passage of the engine, and the air bypass valve is opened when the exhaust brake is operated. In operation, intake air can be quickly supplied to the combustion chamber of the engine via the air bypass passage.

According to the eighth aspect of the present invention, the gas fuel is LP
By using G or CNG, the effect of optimizing the air-fuel ratio when the exhaust brake is released becomes effective.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of the present invention.

FIG. 2 is a time chart illustrating an operation of each control unit in the embodiment of the present invention.

FIG. 3 is a block diagram illustrating a connection state to a control unit according to the embodiment of the present invention.

FIG. 4 is a flowchart showing one half of a processing operation performed for exhaust brake control in a control unit.

FIG. 5 is a flowchart showing another half of the processing operation in the control unit.

FIG. 6 is a diagram illustrating characteristics according to an engine speed at a set time for opening an injector.

FIG. 7 is a diagram showing an overall configuration of an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LPG engine 6 Combustion chamber 8 Intake passage 11 Throttle valve 13 Air bypass passage 14 Air bypass valve 18 Exhaust passage 22 Exhaust shutter valve 26 Fuel supply device (Fuel supply means) 27 Main fuel supply device (Main fuel supply means) 28 Mixer 31 Regulator 35 Fuel cut valve 40 Secondary fuel supply device (secondary fuel supply means) 42 Injector 45 Feedback solenoid valve 50 Control unit 51 Exhaust brake switch 52 Idle switch 53 Clutch switch 54 Neutral switch 55 Engine rotation switch 57 Exhaust brake means 58 Fuel supply control Means t1, t2 Set time

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 41/10 330 F02D 41/10 330K 41/12 315 41/12 315 43/00 301 43/00 301K 301H F02M 21/02 301 F02M 21 / 02 301N 21/04 21/04 G 69/00 F02N 17/08 D F02N 17/08 F02M 69/00 320B (72) Inventor Yasunori Motose 2-4-1 Niho, Minami-ku, Hiroshima-shi, Hiroshima, Japan Inside the corporation

Claims (8)

[Claims] A fuel supply means for supplying gaseous fuel to an intake passage of the engine; an exhaust shutter valve for opening and closing an exhaust passage of the engine; and a fuel supply means for closing the exhaust shutter valve when an exhaust brake is operated. An exhaust brake means for stopping the supply of fuel by the exhaust brake and supplying only intake air to the combustion chamber of the engine; and when the operation of the exhaust brake by the exhaust brake means is released, the fuel is supplied until a set time elapses. An exhaust brake device for a gas-fueled engine, comprising: a fuel supply control means for increasing the amount of gas fuel by the supply means. 2. The exhaust brake device for a gas-fuel engine according to claim 1, wherein the fuel supply control means is configured to increase the set time as the engine speed at the time of releasing the operation of the exhaust brake decreases. An exhaust braking device for a gas-fueled engine, characterized in that: 3. An exhaust brake device for a gas-fueled engine according to claim 1, wherein the fuel supply means is a main fuel supply means for supplying gaseous fuel during normal operation of the engine, and the fuel supply means is different from the main fuel supply means. Auxiliary fuel supply means for supplying gaseous fuel in a system, wherein the fuel supply control means is configured to increase the amount of gaseous fuel by supplying gaseous fuel to the intake passage of the engine by the auxiliary fuel supply means. An exhaust brake device for a gas-fueled engine. 4. An exhaust brake device for a gas-fuel-operated engine according to claim 3, wherein the auxiliary fuel supply means supplies the gas fuel to an intake passage downstream of the gas fuel supply position by the main fuel supply means. An exhaust braking device for a gas-fueled engine, comprising: 5. The exhaust brake device for a gas-fueled engine according to claim 3 or 4, wherein the main fuel supply means is configured to suck gas fuel from the regulator by negative pressure in the intake passage. The exhaust brake device of a gas-fuel-type engine, wherein the means is configured to inject and supply gas fuel at a higher pressure than gas gas supplied by the main fuel supply means to the intake passage through an injector in the regulator. . 6. An exhaust brake device for a gas fuel type engine according to claim 5, wherein the injector of the auxiliary fuel supply means injects and supplies gas fuel to an intake passage of the engine when the engine is started. Exhaust braking system for gas-fueled engines. 7. An exhaust brake device for a gas-fuel engine according to claim 1, wherein said air bypass passage opens and closes an air bypass passage for supplying intake air by bypassing a throttle valve in an intake passage. An exhaust brake device for a gas-fuel-type engine, comprising: an air bypass valve; wherein the exhaust brake means is configured to open the air bypass valve when the exhaust brake is operated. 8. An exhaust brake device for a gas fuel type engine according to claim 1, wherein the gas fuel is LPG or CNG.