JP2003041984A - Start control for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibrations in a start of a diesel engine without using a conventional decompressor mechanism. SOLUTION: A start controller for the diesel engine 100a is provided with a valve 84 provided in an intake manifold 12 of the diesel engine, and a start control part 200 reducing a suction air capacity to at least one combustion chamber interior of the diesel engine during cranking by closing the valve before cranking of the diesel engine. It is also provided with an air sucking part connected to an intake passage between the valve and a plurality of combustion chambers of the diesel engine and sucking air. The start control part 200 has the air sucking part suck air after closing the valve and before cranking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine starting control technique.

[0002]

2. Description of the Related Art When a diesel engine is started, a large vibration tends to be generated due to a compression reaction force of air in each combustion chamber. Therefore, conventionally, a so-called decompression mechanism has been used to reduce vibration at the time of starting. As is well known, the decompression mechanism is a mechanism that keeps the intake valve in an open state during low rotation at the time of starting, so that air is not compressed. As the decompression mechanism,
For example, the one described in JP-A-8-28313 has been proposed.

[0003]

However, there is a problem that the decompression mechanism complicates the structure of the engine and causes a cost increase. So, from the past,
A technique for reducing vibration at the time of starting a diesel engine without using a decompression mechanism has been desired.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a technique for reducing the vibration at the time of starting a diesel engine without using a conventional decompression mechanism. .

[0005]

In order to achieve the above object, a starting control device for a diesel engine according to the present invention includes an intake stop valve provided in an intake passage of the diesel engine and the diesel engine. And a start control unit that reduces the intake air amount into at least one combustion chamber of the diesel engine at the time of cranking by closing the intake stop valve before cranking the engine.

In this starting control device, the amount of intake air into the combustion chamber of the engine during cranking decreases, so the compression reaction force of air in the combustion chamber decreases, and as a result, the compression reaction force results. Vibration can be reduced.

The intake stop valve may be provided in each of a plurality of branch pipes of the intake manifold.

According to this structure, since the volume of the air passage from the intake stop valve to the combustion chamber is small, the compression reaction force of air in the combustion chamber is further reduced.

Alternatively, the intake stop valve may be provided in a common intake passage portion of a plurality of combustion chambers before branching of the intake manifold.

According to this structure, since one intake stop valve may be provided for a plurality of combustion chambers, the structure becomes simpler.

The start control device further includes an air suction unit that is connected to an intake passage between the intake stop valve and a plurality of combustion chambers of the diesel engine and sucks air. The air suction unit may suck air before the cranking after closing the intake stop valve.

According to this structure, the amount of air in the combustion chamber during cranking is further reduced, so that the vibration due to the compression reaction force of air is further reduced.

The starting control device further sets the crank position before cranking to any one of the plurality of combustion chambers without any overlap between the exhaust valve and the intake valve. A crank position adjuster may be provided to adjust the intake valves of the two combustion chambers to the open range.

According to this structure, the air in the combustion chamber in which the intake valve is in the open state is sucked by the air suction portion before the cranking, so that the amount of air in the combustion chamber surely decreases. Therefore, the vibration caused by the compression reaction force of air is further reduced.

The crank position adjuster adjusts the crank position before cranking in any of the plurality of combustion chambers so that there is no valve overlap between the exhaust valve and the intake valve, and any two combustion chambers. It is preferable to adjust the intake valve of the chamber so that both are in the open state.

By adjusting the crank position within this range, the air in the two combustion chambers is sucked, so that it is possible to further reduce the vibration at the time of starting.

Further, the crank position adjusting unit adjusts the crank position when the engine is stopped by the driver to stop the engine within a range near the compression top dead center of any one of the plurality of combustion chambers. You may

According to this structure, the air in the combustion chamber in which the piston has stopped at a position near the compression top dead center gradually drops to near atmospheric pressure. Therefore, even if the engine is started from this state, the compression reaction force of the combustion chamber becomes small and the vibration at the time of starting becomes small.

The intake stop valve may be provided in a part of a plurality of branch pipes of the intake manifold.

Further, it is provided with an air suction portion which is connected to an intake passage between the intake stop valve and a specific combustion chamber of the diesel engine connected to the specific branch pipe to suck air. The start control unit may cause the air suction unit to suck air before the cranking after closing the intake stop valve.

According to this structure, since the amount of air sucked by the air suction unit is relatively small, the time required for sucking air can be shortened, or an air suction unit having a smaller suction capacity can be used. Can be used.

It should be noted that the starting control device sets the crank position before the cranking to the valve of the intake valve and the exhaust valve of the specific combustion chamber in which the intake valve of the specific combustion chamber is in the open state. You may make it provide the crank position adjustment part which adjusts to the range which does not overlap.

According to this structure, the air in the specific combustion chamber is sucked by the air suction portion before cranking, so that the amount of air in the combustion chamber is surely reduced. Therefore,
Vibration caused by the compression reaction force of air is further reduced.

In the crank position adjusting section, the intake valve of the specific combustion chamber is in an open state, there is no valve overlap between the intake valve and the exhaust valve of the specific combustion chamber, and It is preferable to adjust the crank position within a range from the latter half of the compression stroke to the first half of the expansion stroke in the combustion chamber that is one before the specific combustion chamber in the combustion order.

Alternatively, the crank position adjusting unit adjusts the crank position within a range in which the specific combustion chamber is near the end of the intake stroke and the intake valve of the specific combustion chamber is in an open state. You may

When the engine is stopped in these states, the compressed air gradually leaks to the outside in the combustion chamber immediately before the specific combustion chamber in the order of combustion, and the pressure decreases. When the engine is started from this state, the compression reaction force of the combustion chamber is small, so the vibration at the time of starting is also small.

The air suction unit is connected to each branch pipe of the intake manifold and can individually control whether air is sucked from each branch pipe. The start control unit controls the intake stop. Before the cranking after closing the valve, air is not sucked from the branch pipe connected to the combustion chamber at the crank position where there is valve overlap between the intake valve and the exhaust valve, and there is no valve overlap. The air suction unit may be controlled so as to suck air from a branch pipe connected to the combustion chamber at the crank position.

According to this configuration, since the presence or absence of the suction of air from each branch pipe is controlled according to the crank position before cranking, the suction of air is reduced so that the compression reaction force in each combustion chamber is reduced. Can be executed. Therefore, it is possible to reduce the vibration at the time of starting without adjusting the crank position before cranking.

The start control device is a device for a hybrid vehicle equipped with the diesel engine and a drive motor, and cranks the diesel engine while the vehicle is being driven by the drive motor. preferable.

In a hybrid vehicle in which the diesel engine is started while the vehicle is running, there is a strong possibility that the vibration at the time of starting the diesel engine may give the driver discomfort or anxiety.
The effect of reducing the vibration at the time of starting is particularly remarkable.

The present invention can be implemented in various modes. For example, a start control device for a diesel engine or a method thereof, a vehicle or a moving body using the start control device, a control device or a control thereof. A computer program for realizing the functions of the method, a recording medium recording the computer program, a data signal embodied in a carrier wave including the computer program, and the like can be realized.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in the following order based on examples. A. Overall structure of hybrid vehicle: B. First Example: C.I. Second embodiment: D. Third Example: E. Fourth Example: F. Fifth Example: G.I. Sixth embodiment: H. Modification

A. Overall structure of hybrid vehicle: Fig. 1
FIG. 1 is an explanatory diagram showing an overall configuration of a hybrid vehicle as an embodiment of the present invention. The wheel drive mechanism of this hybrid vehicle includes a diesel engine 100 and a clutch 1.
10, a drive motor (traction motor) 120,
And an automatic transmission 130. The output shaft 132 of the automatic transmission 130 is coupled to an axle 142 via a differential gear 140. Diesel engine 1
00 is provided with a starter motor 160.

Drive motor 120 and starter motor 160
Is a drive circuit 171, powered by the secondary battery 180.
Each is driven by 172. These motors 1
Reference numerals 20 and 160 denote so-called motor / generators, which can take two operating states, a power running operating state that functions as a motor and a regenerative operating state that functions as a generator. For example, the drive motor 120 is 2 in the power running mode.
The axle 142 receives power from the next battery 180.
Generates power to drive the. In the regenerative operation state, the power of the axle 142 is converted into electric power to charge the secondary battery 180.

The control unit 200 uses various sensors to realize control of the entire vehicle. These sensors include a shift position sensor 212 for detecting the position of the shift lever, an accelerator sensor 214 for detecting the amount of depression of the accelerator by the driver, a brake sensor 216 for detecting the depression pressure of the brake,
A battery sensor 182 for detecting the state of charge SOC of the battery 180 is included. Although the hybrid vehicle includes many other sensors, they are omitted in FIG. 1 for convenience of illustration.

This hybrid vehicle can run in various states. For example, in a relatively low speed state where the hybrid vehicle has started running, the diesel engine 1
The vehicle travels by driving the drive motor 120 while stopping 00. When the hybrid vehicle reaches a predetermined speed after starting traveling, the control unit 200 cranks the diesel engine 100 by using the starter motor 160 to start the diesel engine 100, and shifts to the operation using the diesel engine 100. The diesel engine 100 can be cranked by using the power of the drive motor 120. In this case, the starter motor 160
Can be omitted.

During steady operation, the diesel engine 100 normally requires the power required by the axle 142 (that is, the axle 14).
It is operated so as to generate an output substantially equal to (rotation speed of 2 × torque × coefficient). At this time, diesel engine 1
Almost all of the 00 output is transmitted to the axle 142. On the other hand, when the state of charge SOC of the battery has fallen below a certain value, the diesel engine 100 operates the axle 142.
Operates with an output that exceeds the required power of. At this time, a part of the power of engine 100 is regenerated as electric power by motors 120 and 160 and used for charging secondary battery 180.

When the torque of the diesel engine 100 is insufficient, the drive motor 120 can assist the torque. In this way, the control unit 200 controls the operating states of the two vehicle driving prime movers 100, 120 according to the required values of the vehicle speed and torque and the state of charge SOC of the secondary battery 180.

B. First Embodiment: FIG. 2 is an explanatory diagram showing a schematic configuration of a diesel engine 100 in the first embodiment. The diesel engine 100 is a four-cylinder engine having four combustion chambers # 1 to # 4. Air is supplied to each of the combustion chambers # 1 to # 4 via the manifold 12 of the intake pipe 10. Further, the engine 100 employs a common rail fuel injection system, and the high-pressure fuel pump 74 to the fuel injection valves 72 of the combustion chambers # 1 to # 4 are used.
High pressure fuel is being supplied to. When fuel is injected from the fuel injection valve 72, air and fuel are combusted in the combustion chambers # 1 to # 4, and exhaust gas is discharged from the exhaust pipe 20.

The intake pipe 10 is provided with a supercharger 30. The supercharger 30 includes a turbine 32 provided in the exhaust pipe 20 and a compressor 34 provided in the intake pipe 10.
And a shaft connecting them. The supercharger 30 is a so-called variable nozzle supercharger, and is provided with an actuator 35 for adjusting the opening area of the inlet nozzle of the turbine 32. This actuator 3
5 can reduce the opening area of the inlet nozzle of the turbine 32 during the low power operation of the engine 100, thereby improving the efficiency of the supercharger 30. An intercooler 40 for cooling the compressed air is provided on the downstream side of the compressor 34. An electromagnetic throttle valve 42 and an air flow meter 44 are provided on the upstream side of the compressor 34.

A catalytic converter 50 for purifying exhaust gas is provided in the exhaust pipe 20 downstream of the turbine 32. As the catalyst of the catalytic converter 50, for example, an oxidation catalyst or a NOx occlusion reduction type three-way catalyst can be used. In the exhaust pipe downstream of the catalytic converter 50, E
The GR passage 60 is connected. This EGR passage 60
Is connected to the flow path between the supercharger 30 (compressor 34) of the intake pipe 10 and the throttle valve 42. EGR
An EGR cooler 62 and an EGR valve 64 are provided in the passage 60. As is well known, EGR is a technique for recirculating a part of exhaust gas into a combustion chamber to lower the combustion temperature and thereby improving the quality of exhaust gas. The amount of exhaust gas (EGR amount) recirculated in the intake pipe 10 can be controlled by adjusting the opening degree of the EGR valve 64. In addition, the throttle valve 42
Reduces the pressure in the intake pipe 10 so that exhaust gas is
It has a function that makes it easy to return to. That is, EGR
The amount is controlled by adjusting the opening of the EGR valve 64 and the opening of the throttle valve 42.

Rotation angle sensors 76 and 78 are provided on the crankshaft of the engine 100 and the camshaft for the valve, respectively. The control unit 200 uses these sensors 7
The high-pressure fuel pump 74 and the fuel injection valve 7 depending on the operating condition parameters detected by various sensors including
2. Controls the EGR valve 64, the throttle valve 42, the actuator 35 of the supercharger 30, and the like.

Four branch pipes 14 of the intake manifold 12
An intake stop valve (electromagnetic open / close valve) 16 is provided in each. These four intake stop valves 16 are used to reduce vibration at the time of starting the engine 100, as described below.

FIG. 3 is a graph showing the starting state of the diesel engine 100 in the first embodiment. At time t0 before starting the engine 100, the four intake stop valves 1
6 is set to the fully closed state, and then cranking (rotation of the crankshaft) is started. This cranking is performed by the starter motor 160 with the clutch 110 (FIG. 1) disengaged. Instead of this, the clutch 11
It is also possible to connect 0 and use the power of the drive motor 120 to perform cranking. When cranking,
Since the intake stop valve 16 is fully closed, combustion chambers # 1 to #
Almost no air is sucked into No. 4, so that a compression reaction force of air is hardly generated. Generally, the vibration at the time of starting a diesel engine is mainly caused by the compression reaction force of air in each combustion chamber. As described above, when the engine 100 is cranked with the intake stop valve 16 closed, an excessive compression reaction force does not occur, and therefore vibration at the time of starting can be reduced.

The vibration at the time of starting the diesel engine is particularly remarkable when the engine speed is low, and when the speed exceeds 1000 rpm, the vibration due to the compression reaction force is significantly reduced. The reason for this is that the easiness of vibration of the engine depends on the natural frequency of the mechanism portion including the crankshaft, and the vibration does not resonate when the engine speed becomes sufficiently higher than the natural frequency. . Therefore, in this embodiment, as shown in FIG. 3, the time t when the engine speed N exceeds a predetermined value (for example, 1000 rpm).
At 1, the four intake stop valves 16 are fully opened, and at time t2 thereafter, fuel injection is started to ignite the engine 100. The engine speed at which fuel injection is started is, for example, 12
It is set to 00 rpm.

As described above, in the first embodiment, cranking is started after the intake stop valve 16 provided in each branch pipe 14 of the intake manifold 12 is fully closed before the diesel engine 100 is started. It is possible to reduce the vibration caused by the compression reaction force of the air immediately after the start. Also,
Since the intake stop valve 16 is fully opened after the engine speed N reaches 1000 rpm or more, it is possible to prevent the occurrence of a large vibration that is likely to occur at low speed.

It is preferable that the intake stop valve 16 has a flow passage area of almost zero in the fully closed state.
It is also possible to use a normal throttle valve as the intake stop valve 16. A normal throttle valve normally has some flow paths even when it is fully closed, but the intake stop valve 1
Even if such a throttle valve is used as 6, the effect of reducing vibration can be expected to some extent. However, the intake stop valve 16
As a result, the effect of reducing the vibration is increased by using the valve in which the flow passage area becomes almost zero when fully closed.

Further, the intake stop valve 16 includes the combustion chambers # 1 to #.
It is preferable that the intake port 4 is provided as close as possible. However, instead of providing the intake stop valve 16 in each branch pipe of the intake manifold 12, one intake stop valve may be provided in the intake pipe 10 before branching.

FIG. 4 is a graph showing an example of the driving pattern of the hybrid vehicle. The broken line shows the change of the vehicle speed V, and the solid line shows the change of the engine speed N. In this example, the vehicle speed V increases linearly from time t10 to time t30, runs at a substantially constant vehicle speed from time t30 to time t40, and then linearly decelerates from time t40 to time t50. It is temporarily stopped at time t50.
Then, at times t60 to t70, the same driving pattern as at times t10 to t50 is repeated, and at time t70, the vehicle is completely stopped.

The period marked "EV" in FIG.
The engine 100 is stopped and the drive motor 120 is operating during the "EV traveling mode (electric vehicle mode)", and both the engine 100 and the motor 120 are operating during the period "HB". The period of the “hybrid traveling mode” and the period of “EN” are the periods of the “engine traveling mode” in which the motor 120 is stopped and the engine 100 is operating. Further, during the period marked "EV (regeneration)", the engine 100 is stopped and the motor 120
(Or the starter motor 160) is in the regenerative operation period.

When the vehicle starts traveling at time t10, the vehicle first travels in the EV traveling mode and the drive motor 120
Only works. After that, when the vehicle speed V exceeds a predetermined value at time t20, the control unit 200 starts the diesel engine 100 according to the operation shown in FIG. 3, and shifts to the hybrid travel mode. Time t20 in FIG. 4 corresponds to time t0 in FIG. 3, and FIG. 3 is an enlarged view showing the change in the number of revolutions after time t20 in FIG.

From time t30 (FIG. 4), the normal operating state is entered, the motor 120 is stopped and the engine running mode EN is entered. However, for example, when the required torque cannot be satisfied only by the torque of the engine 100 during acceleration, the insufficient torque is supplemented by the motor 120. When the vehicle decelerates after time t40, the engine 10
0 is stopped, and the motor 120 performs regenerative operation. During the period t50 to t60 during which the vehicle is temporarily stopped, the engine 10
Both 0 and the motor 120 are stopped. Then, in the periods t60 to t70, the same operation as in the periods t10 to t50 is performed.

As described above, in the hybrid vehicle, the diesel engine 100 is started while the vehicle is traveling. At this time, if the vibration accompanying the start of the diesel engine 100 is excessively large, the driver may illusion that the engine 100 is abnormal. Further, since the engine 100 is started many times during one travel, the vibration may cause discomfort to the driver, which may be a serious problem. On the other hand, in the present embodiment, as described above, by performing the cranking with the intake stop valve 16 fully closed before the engine 100 is started, the vibration at the time of starting can be reduced, so that in the hybrid vehicle as described above It is possible to solve the problem of vibration. Further, since the so-called decompression mechanism is unnecessary, the engine structure can be simplified.

C. Second Embodiment: FIG. 5 is an explanatory diagram showing a schematic configuration of a diesel engine 100a in the second embodiment. Intake manifold 1 of this engine 100a
A vacuum pump 82 is connected to 2 via an electromagnetic opening / closing valve 84. In addition, 4 in the first embodiment shown in FIG.
Intake manifold 12 instead of two intake stop valves 16
One intake stop valve 86 is provided in the intake pipe 10 upstream of the intake pipe 10. The vacuum pump 82 and the electromagnetic opening / closing valve 84 configure an air suction unit 80 (also referred to as an “air amount reduction unit”) that reduces the amount of air in the combustion chambers # 1 to # 4 before cranking. The other structure of the second embodiment is the same as that of the first embodiment.

When using this engine 100a,
At the start of cranking (eg, immediately before time t0 in FIG. 3), the intake stop valve 86 is fully closed, the opening / closing valve 84 is fully open, and the vacuum pump 82 is used to intake the intake manifold 12
And the air in the combustion chambers # 1 to # 4 is sucked. Therefore, the amount of air in the combustion chambers # 1 to # 4 at the time of cranking can be reduced, so that the vibration at the time of starting can be further reduced as compared with the first embodiment.

The operation of the vacuum pump 82 is performed, for example, by
It is started at a timing when it is requested to start the engine 100a while the vehicle is traveling. In addition, the vacuum pump 82 is provided at various timings such as the timing when the driver gets into the vehicle and the timing when the vehicle starts the EV traveling operation.
It is also possible to start driving.

D. Third Embodiment: FIG. 6 is an explanatory diagram showing a schematic configuration of a diesel engine 100b in the third embodiment. This engine 100b is the same as the engine 100 (FIG. 2) of the first embodiment except that the electromagnetic opening / closing valve 92 and the vacuum pump 9 are used.
It has a configuration in which an air suction unit 90 composed of 6 and 6 is added. The four branch pipes 14 of the intake manifold 12 are
A vacuum pump 96 is provided through the communication passage 98 and the electromagnetic opening / closing valve 92.
Are commonly connected to.

The procedure for starting the engine 100b is almost the same as that of the second embodiment described above. That is, at the start of cranking, first, the intake stop valve 16 of each branch pipe 14 is fully closed, and then the on-off valve 92 is opened to open the combustion chambers # 1 to # 1.
The vacuum pump 96 sucks the air in # 4. Also in the third embodiment, similarly to the second embodiment, it is possible to greatly reduce the vibration at the time of starting the engine.

The intake stop valve 16 in the third embodiment
To the respective combustion chambers are smaller in volume than the intake passages from the intake stop valve 86 to the respective combustion chambers in the second embodiment. Specifically, the former is at most several hundred cc in total, while the latter is 1000 to 2000 cc.
It is a degree. Therefore, in the third embodiment, the amount of air to be sucked before the cranking is considerably smaller than that in the second embodiment, so that the time required to suck the air by the vacuum pump 96 can be shortened. Therefore, the engine can be started more quickly than in the second embodiment.

Further, since the amount of air to be sucked is smaller than that in the second embodiment, a vacuum pump having a smaller suction capacity can be used, and the space and cost relating to the vacuum pump can be reduced.

However, in the above-described second embodiment, since one intake stop valve 86 may be provided for the four combustion chambers # 1 to # 4, the structure is simpler than that in the third embodiment. There is an advantage.

E. Fourth Embodiment: FIG. 7 is an explanatory diagram showing a schematic configuration of a diesel engine 100c in a fourth embodiment. Air suction part 90a of this engine 100c
Has a configuration in which a vacuum tank 94 is added between the electromagnetic on-off valve 92 of the air suction portion 90 of the engine 100b (FIG. 6) of the second embodiment and the vacuum pump 96. Other configurations are the same as those of the engine 100b of the second embodiment.

The procedure for starting the engine 100c is almost the same as that of the third embodiment described above. That is, before starting the cranking, first, the intake stop valve 16 of each branch pipe 14 is fully closed, and then the on-off valve 92 connected to the vacuum tank 94 is opened to open the air in the combustion chambers # 1 to # 4. Aspirate. The vacuum tank 94 is evacuated by the vacuum pump 96 before the start of this operation. Also in the fourth embodiment, similarly to the third embodiment, it is possible to significantly reduce the vibration at the time of starting the engine.

The vacuum pump 96 is omitted and the combustion chamber #
The vacuum tank 94 may be evacuated in advance by utilizing the pumping of the pistons 1 to # 4.

FIG. 8 is an explanatory view showing a preferable engine stop position in the fourth embodiment. Here, the “engine stop position” means the angle of the crankshaft. FIG. 8A shows the timing of the open state of the intake valves and the exhaust valves of the four combustion chambers # 1, E3, # 4, E2. The arrangement of the combustion chambers follows the order in which the combustion process proceeds. Top dead center TDC and bottom dead center BD in FIG. 8 (A)
C is for the first combustion chamber # 1. Figure 8
The preferable engine stop position range DR1 shown in (A) is defined as follows.

DR1: A range in which there is no valve overlap between the exhaust valve and the intake valve in any of the combustion chambers, and the intake valve of any one of the combustion chambers is in the open state.

FIG. 8B shows the state of each combustion chamber when the engine is stopped at the position P1 (FIG. 8A) within this preferable range DR1. When the on-off valve 92 is opened in this state, the vacuum tank 94 sucks the air in the first combustion chamber # 1. On the other hand, in the other combustion chambers # 2 to # 4, since the intake valve is closed, air is not sucked. After that, when cranking of the engine is started, the compression reaction force in the first combustion chamber # 1 can be significantly reduced, so that the vibration at the start is reduced.

The stop position of the engine is adjusted by rotating the engine using the starter motor 160 (FIG. 1) while detecting the rotation angle of the valve camshaft with the rotation angle sensor 78 (FIG. 6). be able to.

FIG. 9 shows a particularly preferable engine stop position range DR2 in the fourth embodiment. This range DR2 is defined as follows.

DR2: A range in which there is no valve overlap between the exhaust valve and the intake valve in any combustion chamber, and the intake valves of any two combustion chambers are both in the open state.

FIG. 9B shows the state of each combustion chamber when the engine is stopped at the position P2 (FIG. 9A) within this preferable range DR2. In this example, the intake valves of the combustion chambers # 1 and # 2 are open. When the open / close valve 92 is opened in this state, the vacuum tank 94
Since the air in the two combustion chambers # 1 and # 2 is sucked by the above, it is possible to further reduce the vibration at the time of starting as compared with the case of FIG. 8B.

FIG. 10 shows a preferred range DR3 of the engine stop position at the time of key-off in the fourth embodiment. Here, “key off” means turning off the ignition key, and more generally, means a stop operation of the engine by the driver. This range DR3 is defined as follows.

DR3: Range near the compression top dead center of any combustion chamber.

The "predetermined range near the compression top dead center" means a range of compression top dead center ± 30 degrees, but it is preferable to set this range to compression top dead center ± 20 degrees. More preferably, the top dead center is ± 10 degrees.

FIG. 10B shows this preferable range DR3.
10 shows the state of each combustion chamber when the engine is stopped at the position P3 (FIG. 10A). In this example, the second combustion chamber # 2 is in a state immediately before the compression top dead center. If the vehicle is left in this state with the key off, the compressed air in the combustion chamber # 2 gradually leaks to the outside, and the pressure drops to near atmospheric pressure when the engine is started. Even if the engine is started from that state, the compression reaction force of the combustion chamber # 2 is small. Further, since the air in the first combustion chamber # 1 is sucked by the vacuum tank 94, a compression reaction force is hardly generated at the time of starting, and the other combustion chambers # 3 and # 3.
Since # 4 hits at the end of the exhaust process and the expansion process, the compression reaction force is not so much generated. As described above, if the engine is stopped in the preferable range DR3 of FIG. 10, the compression reaction force of the air in the four combustion chambers # 1 to # 4 becomes small, so that the vibration at the time of starting can be reduced. .

As can be understood by comparing FIGS. 9 and 10, the preferable range DR2 of FIG. 9 is included in the preferable range DR3 of FIG. Therefore, when the key is off, the engine may be stopped within the preferable range DR2 in FIG. When the engine is stopped at a position within this range DR2 at the time of key-off, the above-mentioned advantages of the two ranges DR2 and DR3 are simultaneously exhibited. For example, assume that the engine is stopped at position P2 in FIG. 9 when the key is off. In this case, since the fourth combustion chamber # 4 is located immediately after the compression top dead center, the compressed air in the combustion chamber # 4 leaks to the outside and the compression reaction force is reduced. In addition, by exhausting using the vacuum tank 94 before cranking, the two combustion chambers #
The air in 1 and # 2 is sucked. Therefore, in the preferable range DR2 of FIG. 9, it is possible to further reduce the compression reaction force in the four combustion chambers # 1 to # 4.

As described above, in the fourth embodiment, the engine stop position is restricted to one of the preset preferable stop position ranges DR1, DR2, DR3 to reduce the vibration at the time of starting the engine. It is possible to

The preferred engine stop position shown in FIGS. 8 to 10 is the engine 100a of the second embodiment.
(FIG. 5) and the engine 100b of the third embodiment (FIG. 6) can be similarly applied.

F. Fifth Embodiment: FIG. 11 is an explanatory diagram showing a schematic configuration of a diesel engine 100d in the fifth embodiment. This engine 100d has an air suction unit 90.
It is different from the engine 100c of the fourth embodiment (FIG. 7) in that b is connected to only one branch pipe of the intake manifold 12, and other configurations are the same as the engine 100c of the fourth embodiment.

In this engine 100d, the number of combustion chambers in which air is sucked by the vacuum tank 94 is only one. Further, in the engine 100b of the third embodiment (FIG. 6) and the engine 100c of the fourth embodiment (FIG. 7), the communication passage 98 provided for connecting the four branch pipes 14 to each other does not exist. As described above, in the fifth embodiment, since the amount of air to be sucked by the vacuum tank 94 is significantly smaller than that in the fourth embodiment, the vacuum tank 94 and the vacuum pump 96 smaller than those in the fourth embodiment are used. You can

Instead of connecting the air suction portion 90b to only one combustion chamber, it may be connected to two or three combustion chambers. That is, the air suction portion may be connected to a part of the plurality of combustion chambers of the diesel engine.

FIG. 12 is an explanatory view showing a preferable engine stop position in the fifth embodiment. The preferable engine stop position range DR4 shown in FIG.
It is defined as follows.

DR4: A range in which the intake valve of the specific combustion chamber to which the air suction portion is connected is in the open state and there is no valve overlap with the exhaust valve.

FIG. 12B shows this preferable range DR4.
12 shows the state of each combustion chamber when the engine is stopped at the position P4 (FIG. 12A). When the open / close valve 92 is opened in this state, the vacuum tank 94
As a result, the air in the first combustion chamber # 1 is sucked. After that, when the engine cranking is started, especially the first
The compression reaction force in the combustion chamber # 1 is significantly reduced, and the vibration at the start is reduced. In addition, other combustion chambers # 2 to # 4
Since the compression reaction force at the time of starting is smaller than that of the first combustion chamber # 1, the engine can be started by simply fully closing the intake stop valve 16 (FIG. 11) provided in each branch pipe 14 of the intake manifold 12. It is possible to sufficiently reduce the vibration at the time.

FIG. 13 shows a particularly preferable engine stop position range DR5 in the fifth embodiment. This range DR5 is defined as follows.

DR5: The intake valve of the specific combustion chamber to which the air suction section is connected is in the open state, there is no valve overlap with the exhaust valve, and the combustion order is higher than that of the specific combustion chamber. The range in which the previous combustion chamber is in the latter half of the compression stroke to the first half of the expansion stroke.

In the example of FIG. 13, the "combustion chamber one combustion order before the specific combustion chamber" is the second combustion chamber # 2. Further, the "range from the latter half of the compression stroke to the first half of the expansion stroke" means a range of compression top dead center ± 30 degrees, but it is preferable to set this range to compression top dead center ± 20 degrees, and compression top dead center More preferably, it is ± 10 degrees.

The definition of the range DR5 can be rewritten as follows in the case of a 4-cylinder engine.

DR5 ': A range in which a specific combustion chamber to which the air suction portion is connected is near the end of the intake stroke, and the intake valve is in the open state.

FIG. 13B shows this preferable range DR5.
13 shows the state of each combustion chamber when the engine is stopped at position P5 (FIG. 13A). In this example, the second combustion chamber # 2 is in a state immediately before the compression top dead center. If the engine stops in this state, the combustion chamber #
The compressed air in 2 gradually leaks to the outside and the pressure drops. Combustion chamber # 2 even if the engine is started from that state
Since the compression reaction force of is small, the vibration at the time of starting is also small.

The engine stop position is set to the above range D.
In R5, it is more preferable to adjust to "a range in which the combustion chamber one combustion order before the specific combustion chamber is in the expansion stroke". In the example of FIG. 13, this range is a range in which the combustion chamber # 2 is located after the compression top dead center. In this range, since the combustion chamber # 2 is in the expansion stroke, the compression reaction force of the combustion chamber # 2 disappears, and it is possible to further reduce the vibration at the time of starting.

As described above, also in the fifth embodiment, the engine stop position is restricted to one of the preset preferable stop position ranges DR4 and DR5 to reduce the vibration at the time of starting the engine. It is possible.

G. Sixth Embodiment: FIG. 14 is an explanatory diagram showing a schematic configuration of a diesel engine 100e in the sixth embodiment. The engine 100e has an air suction unit 90.
The open / close valve 92 and the suction passage 91 of c are connected to the intake manifold 12
It is different from the engine 100c of the fourth embodiment (FIG. 7) in that each branch pipe is independently provided, and other configurations are the same as the engine 100c of the fourth embodiment. Control unit 20
0 can open and close each on-off valve 92 independently.

FIG. 15 is an explanatory view showing a state of air suction control at the time of engine start in the sixth embodiment. In the sixth embodiment, unlike the above-described fourth and fifth embodiments, the engine stop position (crankshaft angle) is not restricted to a specific range. Instead, vibration at the time of starting is reduced by changing the method of sucking air according to the stop position of the engine.

In FIG. 15A, it is assumed that the engine is stopped at the position P6 just before the exhaust top dead center of the first combustion chamber # 1. FIG. 15 (B) shows the state of each combustion chamber when the engine is stopped at this position P6. At this position P6, the first combustion chamber # 1 is in the valve overlap state. Even if the air in the combustion chamber # 1 in the valve overlap state is sucked by the vacuum tank 94, not only the air in the combustion chamber cannot be exhausted, but also the air in other combustion chambers cannot be exhausted. Therefore, in the sixth embodiment, this problem is solved by closing the on-off valve 92 connected to the combustion chamber in the valve overlap state. That is, FIG.
In the state of 5 (B), the air in the branch pipes of the three combustion chambers # 2 to # 4 and the air in the one combustion chamber # 4 are sucked by the vacuum tank 94. Therefore, the compression reaction force in these combustion chambers can be reduced, and the vibration at the time of starting can be reduced. On the other hand, when none of the combustion chambers is in the valve overlap state, air is sucked from the branch pipes of all the combustion chambers.

Not only the on-off valve 92 connected to the combustion chamber in the valve overlap state, but also the on-off valve 92 connected to another combustion chamber which is expected to have a small compression reaction force at the time of starting. You may make it close at the same time. For example, in the example of FIG. 15B, the third combustion chamber # 3
Is located at a position where the exhaust stroke is to be started, the on-off valve 92 may be closed.

In the sixth embodiment, the on-off valve 92 is provided for each branch pipe in order to individually control the presence or absence of air suction from each branch pipe. However, various other configurations can be adopted as the air suction unit 90c capable of individually controlling whether air is sucked from each branch pipe. For example, a vacuum pump may be individually provided for each branch pipe.

The air suction unit capable of individually controlling the presence or absence of air suction from each branch pipe has one intake stop in the intake pipe 10 upstream of the intake manifold 12, as in the example of FIG. It is also applicable to an engine provided with the valve 86.

As described above, in the sixth embodiment, the air is not sucked from the branch pipe of the combustion chamber in the valve overlap state, but the air is sucked from the branch pipe of the combustion chamber not in the valve overlap state. Therefore, it is possible to reduce the vibration at the time of starting without restricting the stop position of the engine.

H. Modifications: The present invention is not limited to the above-described embodiments and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are also possible. is there.

H1. Modification 1 In the above embodiment, the intake stop valve (electromagnetic on-off valve) 16 is provided in the intake manifold 12, but the intake stop valve 16 may be provided in an intake passage other than the intake manifold. For example, the intake stop valve 16 may be provided at the intake passage position between the collecting portion of the intake manifold and the surge tank, the intake port, or the like.

H2. Modification 2: As a configuration of a hybrid vehicle using a diesel engine and a drive motor,
Various configurations other than those shown in FIG. 1 are possible, and are applicable to various parallel hybrid vehicles and series hybrid vehicles. However, the present invention is particularly effective when applied to a hybrid vehicle of a type in which the diesel engine is not started at the start of running of the vehicle, only the drive motor is used to start running, and then the diesel engine is started during running. Is. The reason for this is that in such a hybrid vehicle, since the diesel engine is started during traveling, there is a strong demand for vibration reduction in order to avoid misunderstanding that the engine is abnormal.

The present invention is also applicable to non-hybrid vehicles that do not have a drive motor. In particular, the effect is remarkable when applied to a vehicle in which the engine automatically stops during a temporary stop (so-called “eco-run” type vehicle). The reason for this is that in the eco-run type vehicle, the diesel engine is started every time the vehicle restarts after being temporarily stopped, so there is a strong demand for vibration reduction.

Furthermore, the present invention is applicable to various vehicles other than automobiles, and various moving bodies such as airplanes and ships. That is, in general, the present invention is applicable to mobile bodies having at least a diesel engine. For example,
In a typical conventional supercharged diesel engine with an intercooler, an intake throttle valve (throttle valve) is provided in the intake passage downstream of the intercooler, and the EGR passage is an exhaust passage upstream of the turbine of the supercharger. And an intake passage downstream of the intake throttle valve. Even in such a conventional supercharged diesel engine with an intercooler, the intake throttle valve is fully closed to function as an intake stop valve,
The present invention can be realized by fully closing the EGR valve arranged in the EGR passage.

H3. Modification 3: In each of the above embodiments, a four-cylinder engine is described, but the present invention can be applied to a diesel engine having an arbitrary number of cylinders other than four cylinders.
Further, although each of the above embodiments has described the engine having the EGR system and the supercharger 30, the present invention is also applicable to an engine having no EGR system or the supercharger 30.

[0106]

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a hybrid vehicle as an embodiment of the present invention.

FIG. 2 is a diesel engine 100 according to the first embodiment.
Explanatory diagram showing a schematic configuration of.

FIG. 3 is a diesel engine 100 according to the first embodiment.
A graph showing the starting state of.

FIG. 4 is a graph showing an example of a driving pattern of a hybrid vehicle.

FIG. 5 is a diesel engine 100 according to the second embodiment.
Explanatory drawing which shows the schematic structure of a.

FIG. 6 is a diesel engine 100 according to the third embodiment.
Explanatory drawing which shows schematic structure of b.

FIG. 7 is a diesel engine 100 according to the fourth embodiment.
Explanatory drawing which shows the schematic structure of c.

FIG. 8 is an explanatory view showing a preferable engine stop position in the fourth embodiment.

FIG. 9 is an explanatory view showing a preferable engine stop position in the fourth embodiment.

FIG. 10 is an explanatory view showing a preferable engine stop position in the fourth embodiment.

FIG. 11 is a diesel engine 10 according to the fifth embodiment.
Explanatory drawing which shows schematic structure of 0d.

FIG. 12 is an explanatory view showing a preferable engine stop position in the fifth embodiment.

FIG. 13 is an explanatory view showing a preferable engine stop position in the fifth embodiment.

FIG. 14 is a diesel engine 10 according to the sixth embodiment.
Explanatory drawing which shows schematic structure of 0c.

FIG. 15 is an explanatory diagram showing a state of air suction control at the time of engine start in the sixth embodiment.

[Explanation of symbols]

10 ... Intake pipe 12 ... Intake manifold 14 ... Branch pipe 16 ... Intake stop valve 20 ... Exhaust pipe 30 ... Supercharger 32 ... turbine 34 ... Compressor 35 ... Actuator 40 ... Intercooler 42 ... Electromagnetic throttle valve 44 ... Air flow meter 50 ... Catalytic converter 60 ... EGR passage 62 ... EGR cooler 64 ... EGR valve 72 ... Fuel injection valve 74 ... High-pressure fuel pump 76, 78 ... Rotation angle sensor 80 ... Air suction unit 82 ... Vacuum pump 84 ... Solenoid on-off valve 86 ... Intake stop valve 90 ... Air suction section 91 ... Suction path 92 ... Electromagnetic on-off valve 94 ... Vacuum tank 96 ... Vacuum pump 98 ... Communication passage 100 ... Diesel engine 110 ... Clutch 120 ... Drive motor 130 ... Automatic transmission 132 ... Output shaft 140 ... Differential gear 142 ... Axle 160 ... Starter motor 171, 172 ... Driving circuit 180 ... Battery 182 ... Battery sensor 200 ... Control unit 212 ... Shift position sensor 214 ... Accelerator sensor 216 ... Brake sensor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 13/08 F02D 13/08 A 5H115 29/06 29/06 D 45/00 362 45/00 362A // B60K 6/02 B60K 9/00 E (72) Inventor Shizuo Sasaki 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G065 AA01 AA03 AA04 CA00 DA04 EA01 GA00 GA05 GA10 GA29 GA31 GA46 HA02 HA03 JA04 JA09 JA11 KA02 3G084 AA00 BA00 CA01 CA07 DA09 DA39 FA38 FA39 3G092 AA00 AA02 AA17 AA18 AC08 BB10 CB02 CB03 DC03 DD00 DD01 EA02 FA14 FA30 FA31 GA01 HE01Z37G013 KA01 LA00 LA01 LA02 LA07 LB11 PA01Z PE03Z PE04Z PE06Z PF03Z PF05Z PF07Z PF08Z PG01A PG01Z 5H115 PA00 PC06 PG04 PI16 PI21 PI29 PO17 PU 01 PU22 PU24 PU25 QE01 QH01 RE01 SE04 SE05 SE06 SE08 TI00 TO21 TO23

Claims (15)

[Claims] 1. A start control device for a diesel engine, comprising: an intake stop valve provided in an intake passage of the diesel engine; and closing the intake stop valve before cranking the diesel engine, whereby the cranking is performed. A starting control unit that reduces the amount of intake air into at least one combustion chamber of the diesel engine during operation. 2. The start control device according to claim 1, wherein
The intake control valve is provided in each of a plurality of branch pipes of the intake manifold. 3. The start control device according to claim 1, wherein
The intake control valve is provided in a common intake passage portion of a plurality of combustion chambers before branching of the intake manifold. 4. The start control device according to claim 2, further comprising an air suction connected to a suction passage between the intake stop valve and a plurality of combustion chambers of the diesel engine to suck air. The starting control device includes a section, and the starting control section causes the air suction section to suck air before the cranking after closing the intake stop valve. 5. The start control device according to claim 4, wherein:
Further, the crank position before cranking is set so that there is no valve overlap between the exhaust valve and the intake valve in any of the combustion chambers of the plurality of combustion chambers, and the intake valve of any one of the combustion chambers is in the open state. A starting control device including a crank position adjusting unit for adjusting a range. 6. The start control device according to claim 5, wherein the crank position adjusting unit sets the crank position before cranking to an exhaust valve and an intake valve in any of the combustion chambers of the plurality of combustion chambers. 1. A start control device for adjusting the intake valve of any two combustion chambers to the range in which both are open, without the valve overlap. 7. The start control device according to claim 5, wherein the crank position adjusting unit sets a crank position when the engine is stopped by a driver's engine stop operation to one of the plurality of combustion chambers. A start control device that adjusts to a range near the compression top dead center of the combustion chamber. 8. The starting control device according to claim 1, wherein:
The start control device, wherein the intake stop valve is provided in a part of a plurality of branch pipes of the intake manifold. 9. The start control device according to claim 8, wherein:
Further, the intake stop valve is provided with an air suction unit that is connected to an intake passage between the specific combustion chamber of the diesel engine connected to the specific branch pipe and that sucks air. The control unit causes the air suction unit to suck air before the cranking after closing the intake stop valve. 10. The start control device according to claim 9, further comprising: a crank position before cranking, in which an intake valve of the specific combustion chamber is in an open state, and A starting control device comprising a crank position adjusting unit for adjusting the intake valve and the exhaust valve so as not to overlap with each other. 11. The start control device according to claim 10, wherein the crank position adjusting unit has an intake valve of the specific combustion chamber in an open state, and the intake valve and the exhaust gas of the specific combustion chamber. A starting control device that adjusts the crank position within a range in which a combustion chamber having no valve overlap with a valve and having a combustion sequence one order before the specific combustion chamber is in the latter half of the compression stroke to the first half of the expansion stroke. 12. The start control device according to claim 10, wherein the crank position adjusting unit is configured such that the specific combustion chamber is near the end of the intake stroke, and the intake valve of the specific combustion chamber is opened. A starting control device that adjusts the crank position to a range that is in a state. 13. The start-up control device according to claim 4, wherein the air suction section is connected to each branch pipe of the intake manifold, and the presence or absence of air suction from each branch pipe is individually checked. Is controllable, and the start control unit is connected to a combustion chamber at a crank position where there is a valve overlap between an intake valve and an exhaust valve before the cranking after closing the intake stop valve. The starting control device controls the air suction unit so as not to suck air from the branch pipe connected to the combustion chamber at the crank position without valve overlap. 14. The start control device according to claim 1, wherein the start control device is a device for a hybrid vehicle including the diesel engine and a drive motor, and the drive motor. A starting control device for cranking the diesel engine while the vehicle is traveling. 15. A method for controlling starting of a diesel engine, comprising: (a) preparing an intake stop valve provided in an intake passage of the diesel engine; and (b) stopping the intake before cranking the diesel engine. Closing the valve to reduce the amount of intake air into at least one combustion chamber of the diesel engine at the time of cranking, the starting control method.