JP2009299529A - Start control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a start control device for an internal combustion engine capable of suppressing the lowering of engine speed in a compression stroke during a starting process. <P>SOLUTION: This start control device is equipped with a hydraulic pressure generator for generating hydraulic pressure, a hydraulic motor for applying a rotational force according to the strength of hydraulic pressure to a crankshaft of the internal combustion engine, an oil passage for supplying hydraulic pressure to the hydraulic motor from the hydraulic pressure generator, a hydraulic supply control valve disposed in the oil passage, and a valve opening means for opening the hydraulic supply control valve according to a start demand of the internal combustion engine. The length of the oil passage is a length in which the strength of oil pressure reaching the hydraulic motor in one of compression strokes from after the start demand until a rotational force auxiliary period passes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a start control device for an internal combustion engine, and more particularly to a start control device for an internal combustion engine having a hydraulic starter system.

  Conventionally, as disclosed in Patent Document 1, for example, a start control device for an internal combustion engine using a hydraulic motor is known. In addition, this publication discloses control for supplying hydraulic pressure to the hydraulic motor until the target rotational speed is obtained. According to such a system, when the internal combustion engine is started, the rotational force of the crankshaft can be assisted until the engine speed is stabilized.

JP 2001-82202 A JP 2004-60527 A JP 2002-349403 A JP 2006-37820 A

  By the way, a compression reaction force is generated in the compression stroke of the internal combustion engine cycle. The rotational force of the crankshaft decreases due to the compression reaction force. However, in the above-described conventional internal combustion engine, the hydraulic motor assists the rotational force of the crankshaft with a constant force regardless of the decrease in the rotational force due to the compression reaction force. Since this assistance does not take into account the time when the compression reaction force occurs, it is not possible to sufficiently suppress the decrease in the rotational force of the crankshaft during the compression stroke. For this reason, there has been a problem that a decrease in the engine speed in the compression stroke cannot be sufficiently suppressed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an internal combustion engine start control device that can suppress a decrease in engine speed during a compression stroke.

In order to achieve the above object, a first invention is a start control device for an internal combustion engine,
A hydraulic pressure generator for generating hydraulic pressure;
A hydraulic motor that applies a rotational force according to the strength of the hydraulic pressure to the crankshaft of the internal combustion engine;
An oil passage for supplying hydraulic pressure from the hydraulic generator to the hydraulic motor;
A hydraulic supply control valve disposed in the oil passage;
Valve opening means for opening the hydraulic pressure supply control valve in response to a start request of the internal combustion engine,
The path length of the oil path is a length that maximizes the strength of the hydraulic pressure reaching the hydraulic motor in any compression stroke after the start request and until the rotational force assist period elapses.
It is characterized by.

The second invention is the first invention, wherein
The path length of the oil path is a length that maximizes the strength of the hydraulic pressure reaching the hydraulic motor in a compression stroke immediately after the start request of the internal combustion engine.

The third invention is the first invention, wherein
The oil path includes a path length varying means for varying the path length.

Moreover, 4th invention is 1st invention or 3rd invention,
A path length control means for variably controlling the path length so that the strength of the hydraulic pressure reaching the hydraulic motor is maximized in all the compression strokes after the start request until the rotational force assist period elapses; It is characterized by providing.

  According to the first aspect, the hydraulic pressure is supplied to the hydraulic motor by opening the hydraulic pressure supply control valve. Also, pulsation occurs in the hydraulic pressure by opening the hydraulic pressure supply control valve. Due to the pulsation of the hydraulic pressure, the strength of the hydraulic pressure supplied to the hydraulic motor varies. In the present invention, the strength of the hydraulic pressure reaching the hydraulic motor can be maximized in any one of the compression strokes after the start-up request until the rotational force assist period elapses. By maximizing the hydraulic pressure reaching the hydraulic motor, the hydraulic motor can apply a large rotational force to the crankshaft. A decrease in engine speed can be suppressed by applying a large rotational force. For this reason, according to the present invention, it is possible to suppress a decrease in the engine speed in the compression stroke immediately after the start request.

  According to the second aspect of the invention, the strength of the hydraulic pressure reaching the hydraulic motor can be maximized particularly in the compression stroke immediately after the start request when the engine speed is low. For this reason, according to the present invention, it is possible to suitably suppress a decrease in the engine speed in the compression stroke immediately after the start request.

  According to the third invention, the path length of the oil passage can be changed. Therefore, according to the present invention, the path length can be set so that the hydraulic pressure reaching the hydraulic motor is maximized in accordance with each compression stroke.

  According to the fourth aspect of the present invention, the path length of the oil passage can be variably controlled so that the hydraulic pressure reaching the hydraulic motor is maximized in each compression stroke after the start request. For this reason, according to this invention, the fall of an engine speed can be suppressed in all the compression strokes.

Embodiment 1 FIG.
[Basic Configuration in Embodiment 1]
FIG. 1 is a diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine 10 (not shown). The internal combustion engine 10 includes a crankshaft 12. A crank angle sensor 14 for detecting the crank angle and the engine speed is disposed in the vicinity of the crankshaft 12. The crankshaft 12 is engaged with a ring gear 16 having a one-way clutch via a gear mechanism. The ring gear 16 is meshed with a constant biting hydraulic starter 18. The hydraulic starter 18 is connected to the inflow side oil passage 20 and the outflow side oil passage 22.

  A reservoir tank 24 for storing oil flowing out from the hydraulic starter 18 is provided downstream of the outflow side oil passage 22. The reservoir tank 24 is connected to the oil pump 26. The oil pump 26 is connected to the pressure accumulation container 28. The pressure accumulating container 28 is connected to the hydraulic starter 18 by the inflow side oil passage 20. The inflow side oil passage 20 is provided with a solenoid valve 30 that controls the flow of oil by opening and closing.

  The system according to the present embodiment includes an ECU (Electronic Control Unit) 50. The aforementioned crank angle sensor 14 is connected to the input side of the ECU 50. The solenoid valve 30 is connected to the output side of the ECU 50.

  The hydraulic starter system is realized by the basic configuration described above. Specifically, first, the oil pump 26 sucks oil from the reservoir tank 24 and raises the pressure. The increased hydraulic pressure is stored in the pressure storage container 28. The hydraulic pressure accumulated in the pressure accumulating container 28 reaches the hydraulic starter 18 through the inflow side oil passage 20 when the ECU 50 opens the solenoid valve 30. The hydraulic starter 18 generates a rotational force corresponding to the reached hydraulic pressure. This rotational force is transmitted to the ring gear 16 meshing with the hydraulic starter 18. Further, the torque is transmitted to the crankshaft 12 through the gear mechanism to assist the rotational force of the crankshaft 12. Thus, the hydraulic starter system is realized by the basic configuration described above.

[Characteristic Configuration in Embodiment 1]
Next, a characteristic configuration of the inflow side oil passage 20 in the system of the present embodiment will be described. In the internal combustion engine cycle, the engine speed increases in the combustion / expansion stroke. On the other hand, in the compression stroke, the engine speed decreases due to the compression reaction force. FIG. 2 is a graph showing changes in engine speed during the starting process of the internal combustion engine. As shown in FIG. 2, in the starting process of the internal combustion engine, the engine speed increases while repeating fluctuations. Regarding the fluctuation of the engine speed, attention is paid to the period A in FIG. 2 showing the compression stroke immediately after the start. Since the compression reaction force is generated in the compression stroke as described above, the engine speed decreases from X to Y. Thereafter, the engine speed increases from Y to Z in the combustion / expansion stroke. As a result, the amount of increase in engine speed that has increased in this one cycle is Z-X. On the other hand, the fluctuation amount of the engine speed is ZY. The greater the variation, the greater the vehicle vibration. In order to suppress vehicle vibration, it is required to reduce the reduction amount XY of the engine speed in the compression stroke.

  In the hydraulic starter system described above, hydraulic pulsation occurs when the solenoid valve 30 is opened to supply hydraulic pressure to the inflow side oil passage 20. Due to the pulsation of the hydraulic pressure, the strength of the hydraulic pressure reaching the hydraulic starter 18 varies (FIG. 3). The rotational force applied to the crankshaft 12 by the hydraulic starter 18 also fluctuates in accordance with the fluctuation of the hydraulic pressure. For this reason, the rotational force that the hydraulic starter 18 applies to the crankshaft 12 is maximized at the timing when the strength of the hydraulic pressure is maximized.

  Therefore, in the system of the present embodiment, the path length of the inflow side oil passage 20 is set so that the strength of the hydraulic pressure supplied to the hydraulic starter 18 is maximized in the compression stroke immediately after the start when the engine speed is low. It was decided to constitute.

  According to the above configuration, the hydraulic pressure reaching the hydraulic starter 18 can be maximized in the compression stroke immediately after starting. By maximizing the hydraulic pressure, the rotational force applied to the crankshaft 12 by the hydraulic starter 18 is also maximized. By making the rotational force maximum, the compression reaction force in the compression stroke can be suitably suppressed. Therefore, it is possible to suppress a decrease in engine speed during the compression stroke. FIG. 4 is a specific example showing fluctuations in the engine speed in the compression stroke immediately after starting. As shown in FIG. 4, in the system of this embodiment (broken line 52), it is possible to suppress a decrease in the engine speed in the compression stroke as compared with a comparison target (solid line 54) that does not consider hydraulic pulsation. For this reason, according to the system of the present embodiment, it is possible to suppress a decrease in the engine speed in the compression stroke immediately after the start using the pulsation of hydraulic pressure. By suppressing the decrease in the engine speed, fluctuations in the engine speed can be reduced. If the fluctuation of the engine speed is reduced, vehicle vibration can be suppressed. Further, by suppressing the decrease in the engine speed, it becomes easy to increase the amount of increase in the engine speed in the cycle immediately after starting.

  By the way, in the system of the first embodiment described above, the time when the strength of the hydraulic pressure reaching the hydraulic starter 18 is maximized is the compression stroke immediately after starting, but this time is not limited to this. . The compression stroke may be any one of the compression strokes after the start request is determined to be complete until the rotational force assist to the crankshaft 12 by the hydraulic starter 18 is stopped.

  In the first embodiment described above, the hydraulic starter 18 is in the “hydraulic motor” in the first invention, the inflow side oil passage 20 is in the “oil passage” in the first invention, and the solenoid valve 30 is in the above-described first embodiment. It corresponds to the “hydraulic supply control valve” in the first invention. Further, in the first embodiment, after the start request is made, it is determined that the start is completed, and the period from when the hydraulic starter 18 stops assisting the rotational force to the crankshaft 12 is the “rotational force assist” in the first invention. Corresponds to "period".

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 50 to execute a routine of FIG. 8 described later in the configuration shown in FIG. 5 described later. FIG. 5 is a diagram for explaining a system configuration according to the second embodiment of the present invention. Since the system configuration in FIG. 5 includes the same configuration as the system in FIG. 1 described above, common configurations are denoted by the same reference numerals, and description thereof is simplified or omitted.

[System Configuration of Embodiment 2]
As shown in FIG. 5, a three-way valve 32 is disposed downstream of the solenoid valve 30 described in FIG. By the three-way valve 32, the inflow side oil passage 20 is branched into a first oil passage 20a and a second oil passage 20b. Downstream of the first oil passage 20 a and the second oil passage 20 b is connected to the hydraulic starter 18.

[Features of Embodiment 2]
In the system according to the first embodiment described above, the strength of the hydraulic pressure reaching the hydraulic motor 18 in the compression stroke immediately after starting can be maximized. As a result, it is possible to suppress a decrease in the engine speed in the compression stroke immediately after starting. FIG. 6 is a diagram showing changes in the engine speed during the starting process. As shown in FIG. 6, in the starting process, the engine speed increases stepwise while repeating a decrease in the compression stroke and an increase in the combustion / expansion stroke. In order to suppress the fluctuation of the engine speed that causes the vehicle vibration throughout the entire starting process, it is necessary to suppress a decrease in the engine speed in each compression stroke.

  Therefore, in the system of the present embodiment, the first oil passage 20a having a path length in which the strength of the hydraulic pressure reaching the hydraulic starter 18 in the initial compression stroke reaches a maximum, and reaches the hydraulic starter 18 in the later compression stroke. The second oil passage 20b having a path length that maximizes the hydraulic pressure is provided. Further, both passages 20a and 20b are switched by the three-way valve 32 so that the strength of the hydraulic pressure reaching the hydraulic starter is maximized in each compression stroke.

  An outline of more specific control will be described with reference to FIG. FIG. 7 is a timing chart for explaining characteristic operations executed in the system of the present embodiment. 7A to 7D respectively show the compression stroke of the internal combustion engine cycle.

FIG. 7A is a diagram showing fluctuations in engine speed during the starting process. A solid line 60 indicates the fluctuation of the engine speed to be compared. The comparison target does not take into account the pulsation of the hydraulic pressure that occurs when the hydraulic pressure is supplied to the hydraulic starter 18. As shown in FIG. 7A, in the comparison target, the engine speed is greatly decreased in each of the compression strokes A to D.
On the other hand, in the system of the present embodiment, the control of the three-way valve 32 that switches the hydraulic paths 20a and 20b controls the strength of the hydraulic pressure reaching the hydraulic starter in each of the compression strokes A to D in FIG. It is maximal. Therefore, in the system of the present embodiment, it is possible to suppress a decrease in the engine speed in each of the compression strokes A to D as indicated by a broken line 62 in FIG.

  FIG. 8 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. In the routine shown in FIG. 8, the ECU 50 first acquires the crank angle after the start request by the crank angle sensor 14 (step 100). Next, it is determined whether or not the acquired crank angle is greater than or equal to the path length change value (step 110). Specifically, for each compression stroke, the ECU 50 sets a path (first oil path 20a or second oil path 20b) that maximizes the hydraulic pressure reaching the hydraulic starter 18, and a path length change timing (crank angle). Is stored in advance. As the initial value of the path length change value, a path length change timing corresponding to the compression stroke immediately after starting is set.

  When it is determined that the crank angle is smaller than the path length change value, the ECU 50 ends this routine. On the other hand, when it is determined that the crank angle is equal to or greater than the path length change value, the ECU 50 sets a path for supplying oil to the hydraulic starter 18 (step 120). Specifically, the ECU 50 acquires a route (first oil passage 20a or second oil passage 20b) corresponding to the route length change timing from the map described above. Then, the three-way valve 32 is set so as to supply hydraulic pressure to the path. Thereafter, the next route length change timing is set as the route length change value of the next routine (step 130).

  As described above, according to the routine shown in FIG. 8, the hydraulic pressure can be supplied to the determined first oil passage 20a or the second oil passage 20b at each path length change timing. Therefore, the strength of the hydraulic pressure reaching the hydraulic starter 18 in each compression stroke of the starting process can be maximized. By maximizing the hydraulic pressure, the rotational force applied to the crankshaft 12 by the hydraulic starter 18 is also maximized. Therefore, it is possible to suppress a decrease in engine speed in each compression stroke of the starting process. By suppressing the decrease in the engine speed, fluctuations in the engine speed can be reduced. Therefore, in the system of the present embodiment, it is possible to reduce vehicle vibration throughout the starting process. Moreover, it becomes easy to increase the increase amount of the engine speed per cycle by suppressing the decrease of the engine speed.

  By the way, in the system of the second embodiment described above, the path for supplying the hydraulic pressure to the hydraulic starter 18 is the two paths of the first oil path 20a and the second oil path 20b, but this path is limited to this. It is not a thing. Three or more paths having different path lengths may be used.

  Further, in the system of the second embodiment described above, the configuration in which the path length of the oil path is variable is realized by switching a plurality of paths having different path lengths, but the path length of the oil path is variable. However, the configuration is not limited to this. For example, it is good also as implement | achieving by one oil path provided with the actuator which expands / contracts path | route length.

  Further, in the system of the second embodiment described above, the timing for changing the path length is determined based on the crank angle, but the determination criterion for this timing is not limited to this. For example, the determination may be made based on the elapsed time after the start request.

In the second embodiment described above, the three-way valve 32, the first oil passage 20a, and the second oil passage 20b correspond to the “path length varying means” in the third aspect of the invention.
Further, here, the “route length control means” in the fourth aspect of the present invention is realized by the ECU 50 executing the processing of steps 100 to 130 described above.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a figure which shows the fluctuation | variation of the engine speed immediately after starting. It is a figure which shows the fluctuation | variation of the hydraulic pressure in a hydraulic starter inlet. It is a figure for demonstrating an example of the operation | movement implement | achieved in the system of Embodiment 1 of this invention. It is a figure for demonstrating the system configuration | structure of Embodiment 2 of this invention. It is a figure which shows the fluctuation | variation of the engine speed of a starting process. It is a timing chart for demonstrating an example of the operation | movement implement | achieved in the system of Embodiment 2 of this invention. It is a flowchart of the control routine performed in the system of Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Crankshaft 14 Crank angle sensor 16 Ring gear 18 Hydraulic starter 20 Inflow side oil passage 20a, 20b 1st oil passage, 2nd oil passage 24 Reservoir tank 26 Oil pump 28 Pressure accumulating container 30 Solenoid valve 32 Three-way valve 50 ECU

Claims (4)

A hydraulic pressure generator for generating hydraulic pressure;
A hydraulic motor that applies a rotational force according to the strength of the hydraulic pressure to the crankshaft of the internal combustion engine;
An oil passage for supplying hydraulic pressure from the hydraulic generator to the hydraulic motor;
A hydraulic supply control valve disposed in the oil passage;
Valve opening means for opening the hydraulic pressure supply control valve in response to a start request of the internal combustion engine,
The path length of the oil path is a length that maximizes the strength of the hydraulic pressure reaching the hydraulic motor in any compression stroke after the start request and until the rotational force assist period elapses.
A start control device for an internal combustion engine. The path length of the oil path is such that the strength of the hydraulic pressure reaching the hydraulic motor is maximized in the compression stroke immediately after the start request of the internal combustion engine,
The start control device for an internal combustion engine according to claim 1. The oil path is a path length varying means for varying the path length,
The start control device for an internal combustion engine according to claim 1, comprising: Path length control means for variably controlling the path length so that the strength of the hydraulic pressure reaching the hydraulic motor is maximized in all the compression strokes after the start request until the rotational force assist period elapses;
The start control device for an internal combustion engine according to claim 1 or 3, further comprising:

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