JP2003161192A - Start controlling device of internal-combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain stable combustion at starting of an engine. <P>SOLUTION: There are formed a first cam peak making an intake valve cam open the intake valve during an intake stroke and a second cam peak making the intake valve open during an exhaust stroke. When a displacement amount D of a piston coupled to the cam becomes larger, the cam is made to be movable in a cam axial line direction so that lifting magnitude of the intake valve becomes larger by the second cam peak. In cases where the displacement amount D of the piston is larger than an allowable largest displacement amount DM thereof when a motor switch is turned on, a fuel injection is inhibited (OFF) to prevent combustion from generating. Further, the displacement amount D of the piston is made small by controlling an actuator driving the piston and then the fuel injection is made to start (ON) when the displacement amount D of the piston becomes less than the allowable largest displacement amount DM thereof. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start control device for an internal combustion engine.

[0002]

2. Description of the Related Art An internal combustion engine in which an intake valve cam for opening and closing an intake valve has a first cam crest for opening the intake valve in an intake stroke and a second cam crest for opening the intake valve in an exhaust stroke. The engine is publicly known (see JP 2001-59431 A). In this internal combustion engine, since the intake valve is opened in the exhaust stroke, the burnt gas in the combustion chamber flows back into the intake passage,
Then, it flows into the combustion chamber with fresh air. This burned gas acts in the same manner as exhaust gas recirculation (hereinafter referred to as EGR) gas, and therefore it is not necessary to provide an EGR passage extending from the exhaust passage to the intake passage.

Further, in this internal combustion engine, the intake valve cam is held movably in the cam axis direction, and when the intake valve cam is moved in the cam axis direction, the lift amount of the intake valve due to the second cam crest is increased. The second cam crest is formed so as to be changed, and the intake valve cam is moved in the cam axis direction based on the engine operating state. That is, the lift amount of the intake valve by the second cam crest is controlled by controlling the position of the intake valve cam in the cam axis direction, thereby controlling the amount of burnt gas that can act as EGR gas. There is.

[0004]

However, the position of the intake valve cam in the cam axis direction when the engine is to be started is generally the position when the engine is stopped, and therefore the intake valve is set to the second position when the engine is started. The cam may open the valve. In this case, the burned gas is returned to the combustion chamber as described above, that is, not only the inert gas exists in the combustion chamber but also the amount of fresh air decreases. Therefore, combustion which is originally unstable at the time of starting the engine becomes more unstable, and there is a possibility that the engine starting cannot be completed promptly or the engine starting cannot be completed.

Particularly, when the initial explosion occurs, a large negative pressure is generated in the intake passage, and a large amount of burned gas may flow back into the intake passage due to the large negative pressure. Therefore, there is a possibility that combustion becomes particularly unstable immediately after the initial explosion.

Therefore, an object of the present invention is to provide a starting control device for an internal combustion engine, which can obtain stable combustion when starting the engine.

[0007]

According to the first aspect of the present invention, there is provided lift amount varying means capable of changing the lift amount of an intake valve or an exhaust valve, and when the engine is to be started. At this time, it is determined whether the lift amount of the intake valve or the exhaust valve obtained in the state of the lift amount varying means is outside the predetermined allowable range, and it is determined that the lift amount is outside the allowable range. In such a case, combustion is prevented from occurring.

According to the second aspect of the invention, in the first aspect of the invention, when the lift amount is judged to be outside the allowable range, the action of supplying fuel to the engine is prohibited to prevent combustion from occurring. I am trying to do it.

According to the third aspect of the invention, in the first aspect of the invention, the cam for opening and closing the intake valve opens the intake valve in the intake stroke and the first cam crest for opening the intake valve in the intake stroke. A second cam crest, wherein the lift amount varying means is capable of changing the lift amount of the intake valve by the second cam crest, and the intake valve by the second cam crest when the engine should be started. When the lift amount is larger than a predetermined allowable amount, combustion is prevented from occurring.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a cam that opens and closes the exhaust valve opens the exhaust valve in the exhaust stroke, and the first cam mountain opens the exhaust valve in the intake stroke. A second cam crest, wherein the lift amount varying means can change the lift amount of the exhaust valve by the second cam crest, and the exhaust valve by the second cam crest when the engine should be started. When the lift amount is larger than a predetermined allowable amount, combustion is prevented from occurring.

According to the fifth aspect, the third or fourth aspect
In the second invention, the second cam lobes are movably held in the cam axis direction, and when the second cam lobes are moved in the cam axis direction, an intake valve or an exhaust gas by the second cam lobes is provided. The second cam lobe is shaped so that the lift amount of the valve is changed, and the position of the second cam lobe in the cam axis direction when the engine is to be started is detected and the intake valve or It is determined whether the lift amount of the exhaust valve is larger than the allowable amount.

According to a sixth aspect of the invention, in the first aspect of the invention, when it is determined that the lift amount is outside the allowable range, the lift amount varying means is controlled so that the lift amount falls within the allowable range. Equipped with return means.

Further, according to the seventh invention, in the sixth invention, when the lift amount is judged to be out of the allowable range, the cranking action is performed while preventing the combustion from occurring, and the cranking action is performed. If it is determined that the lift amount is out of the allowable range even if a predetermined allowable time has elapsed after the start of the combustion, the combustion is started based on the predetermined abnormal time parameter.

Further, according to the eighth invention, in the sixth invention, when the return amount is within the allowable range by the returning means, combustion is started based on a predetermined normal time parameter. ing.

[0015]

FIG. 1 shows the case where the present invention is applied to a four-stroke spark ignition type internal combustion engine. Referring to FIG. 1, 1 is an engine body, 2 is a piston, 3 is a combustion chamber,
4 is an electrically controlled fuel injection valve, 5 is a spark plug, 6 is an intake valve,
Reference numeral 7 is an intake valve drive device for opening and closing the intake valve 6, and 8
Is an intake port, 9 is an exhaust valve, 10 is an exhaust valve driving device for driving the exhaust valve 9 to open and close, and 11 is an exhaust port. The intake port 8 is connected to a surge tank 13 via a corresponding intake branch pipe 12, and the surge tank 13 is connected to an air cleaner 15 via an intake duct 14. A throttle valve 17 driven by a step motor 16 is arranged in the intake duct 14. On the other hand, exhaust port 1
1 is connected via an exhaust manifold 18 and an exhaust pipe 19 to a catalytic converter 20 containing a catalyst.

The electronic control unit 30 is composed of a digital computer, and a ROM (read only memory) 32, a RAM (random access memory) 33, a CPU (microprocessor) 34, and a power source which are connected to each other by a bidirectional bus 31 are always connected. B-RAM 35 that has been
It has a (backup RAM), an input port 36, and an output port 37. A water temperature sensor 38 that generates an output voltage proportional to the engine cooling water temperature is attached to the engine body 1, and a pressure sensor 39 that generates an output voltage proportional to the pressure in the surge tank 13 is attached to the surge tank 13. A load sensor 40 that generates an output voltage proportional to the amount of depression of the accelerator pedal is connected to the accelerator pedal (not shown). These sensors 38, 39, 40
The output signal of is input to the input port 36 via the corresponding AD converter 41. Further, at the input port 36, a rotation speed sensor 42 for generating an output pulse representing the engine rotation speed,
It is connected to a starter motor switch 43 that generates an output pulse indicating that it is turned on. On the other hand, the output port 36 is connected to the fuel injection valve 4, the spark plug 5, the step motor 16, and the starter motor 45 via the corresponding drive circuit 44. The starter motor 45 is driven only while the starter motor switch 43 is on.

As shown in FIG. 2, the intake valve drive device 7 is supported by a cam shaft 60 which is held so as to be rotatable around the cam shaft M and movable in the direction of the cam shaft M, and the cam shaft 60. An intake valve cam 61 for opening and closing the intake valve 6,
A hydraulic actuator 62 for moving the cam shaft 60 in the direction of the cam axis M together with the cam 61.

As shown in FIG. 3, the cam 61 has two cam ridges 61a and 61b. The first cam crest 61a is for opening the intake valve 6 in the intake stroke as shown by the solid line X in FIG.
Is for opening the intake valve 6 in the exhaust stroke as indicated by solid lines Y and Z in FIG. In the example shown in FIG. 4, the intake valve 6 is opened by the second cam crest 61b in the middle of the exhaust stroke, and the entire valve opening period by the second cam crest 61b is in the exhaust stroke. The dotted line W in FIG. 4 indicates the amount of displacement of the exhaust valve 9.

When the intake valve 6 is opened in the exhaust stroke, the burnt gas in the combustion chamber 3 flows back into the intake port 8 and then flows into the combustion chamber together with fresh air. Therefore, this burned gas is
It will act like a GR gas.

The second cam crest 61b is formed so as to be inclined with respect to the cam axis M direction. Therefore, when the position of the cam 61 or the second cam crest 61b with respect to the intake valve 6 in the cam axis M direction is changed. Intake valve 6 by the second cam crest 61b
The lift amount of will be continuously changed. A solid line Y in FIG. 4 shows a case where the lift amount of the intake valve 6 by the second cam crest 61b is relatively large, and a solid line Z shows a case where the lift amount of the intake valve 6 by the second cam crest 61b is relatively small. Is shown. On the other hand, even if the position of the cam 61 or the first cam crest 61a with respect to the intake valve 6 in the cam axis M direction is changed, the lift amount of the intake valve 6 by the first cam crest 61a is maintained constant.

Referring again to FIG. 2, the actuator 6
2 has a hydraulic chamber 63 filled with operating oil, and a piston 64 fixed to one end of the cam shaft 61 has a hydraulic chamber 6
It is housed movably within 4. The piston 64 defines a lift amount increasing chamber 65 and a lift amount decreasing chamber 66 having variable volumes in the hydraulic chamber 63.

The hydraulic pressure in the lift amount increasing chamber 65 and the lift amount decreasing chamber 66 is controlled by an electromagnetic hydraulic control valve 67. Specifically, the hydraulic control valve 67 includes a hydraulic control chamber 69 that movably accommodates a valve body 68, and the hydraulic control chamber 69 is connected to the lift amount increasing chamber 65 and the lift amount decreasing chamber 66, respectively. On the other hand, it is connected to the engine-driven oil pump 70 and the return passage 71, respectively. In FIG. 2, 72 indicates an oil tank. The hydraulic control valve 67 is also connected to the output port 36 of the electronic control unit 30 via the corresponding drive circuit 44.

When the valve body 68 is in the position shown in FIG. 2, the lift amount increasing chamber 65 and the lift amount decreasing chamber 66 are shut off from the oil pump 70 and the return passage 71, so that the lift amount increasing chamber 65 and the lift amount decreasing chamber are provided. Since the hydraulic pressure in 66 is maintained, the positions of the piston 64 and the cam 61 in the cam axis M direction are maintained. When the valve body 68 is moved leftward from the position shown in FIG. 2, the lift amount increasing chamber 65 is connected to the oil pump 70 while being blocked from the return passage 71,
The lift amount reduction chamber 66 is connected to the return passage 71 while being blocked from the oil pump 70, and thus the piston 64 and the cam 61 move to the right side in FIG. On the other hand, when the valve body 68 is moved to the right from the position shown in FIG. 2, the lift amount increasing chamber 65 is connected to the return passage 71 while being blocked from the oil pump 70, and the lift amount decreasing chamber 6 is
6 is blocked from the return passage 71 while the oil pump 70
2 and thus the piston 64 and the cam 61 are shown in FIG.
Move to the left at.

In this way, the piston 64 or the cam 61 is
Is moved in the cam axis M direction, or the position of the piston 64 or the cam 61 with respect to the intake valve 6 in the cam axis M direction is changed. As a result, the lift amount of the intake valve 6 by the second cam crest 61b is changed as described with reference to FIGS. 3 and 4.

That is, if the piston displacement amount, which is the displacement amount of the piston 64 or the cam 61 from the predetermined reference position in the direction of the cam axis M, is represented by D, the piston displacement amount D becomes large as shown in FIG. As it becomes, the lift amount L of the intake valve 6 by the second cam crest 61b continuously increases. However, in the example shown in FIG. 5, the lift amount L is maintained at zero when the piston displacement amount D is less than or equal to the threshold value DD.

The amount of burnt gas returned from the intake port 8 into the combustion chamber 3 depends on the lift amount L of the intake valve 6 by the second cam crest 61b, and this lift amount L depends on the piston displacement amount D. . Therefore, by changing the piston displacement amount D, the amount of burnt gas returned into the combustion chamber 3 can be controlled.

In the example shown in FIG. 2, the piston displacement amount D
A displacement amount sensor 73 for generating an output voltage proportional to is attached to the piston 64, and the output signal of this sensor 73 is transmitted via the corresponding AD converter 41 to the electronic control unit 30.
Is input to the input port 36 of the. Therefore, if the hydraulic pressure control valve 67 is controlled so that the piston displacement amount D detected by the displacement amount sensor 73 matches the target amount, the amount of burnt gas returned into the combustion chamber 3 can match the target amount. You will be able to Here, the piston displacement amount D is the piston 6
4 or the position of the cam 61 with respect to, for example, the intake valve 6 in the cam axis M direction, and therefore the displacement sensor 73 detects the position of the piston 64 or the cam 61 in the cam axis M direction.

Further, in the example shown in FIG. 2, a hemispherical sliding member 6b is inserted between the cam 61 and the valve lifter 6a provided at the top of the intake valve 6. This sliding member 6b
Is movably accommodated in a hemispherical groove formed on the top surface of the valve lifter 6a, and can be moved in the groove according to the shape of the cam surface of the cam 61.

By the way, when, for example, an ignition switch (not shown) is turned off to stop the engine, the valve body 68 of the hydraulic control valve 67 is fixed at the position shown in FIG. Therefore, the piston displacement amount D when the engine is started next is held at the displacement amount when the ignition switch is turned off. Therefore, at this time, the intake valve 6 is opened by the second cam crest 61b. There is a case. In this case, combustion becomes unstable as described in the beginning.

To solve this problem, burned gas is generated in the combustion chamber 3 when the lift amount L of the intake valve 6 by the second cam crest 61b is large, that is, when the piston displacement amount D is large. You just have to stop doing it. Therefore, in the embodiment according to the present invention, the piston 6 capable of ensuring a good engine start.
4 or the maximum allowable displacement DM of the cam 61 is obtained in advance, and when the engine is to be started, for example, when the piston displacement D when the starter motor switch 43 is turned on is larger than the maximum allowable displacement DM, combustion is performed. I try to prevent it from happening. Specifically, the fuel injection action from the fuel injection valve 4 is prohibited. as a result,
The engine can be started reliably and promptly.

In the spark ignition type internal combustion engine as shown in FIG. 1, combustion will not occur if either one of the fuel injection action and the ignition action is prohibited. Therefore, it is also possible to prohibit the ignition action while performing the fuel injection action. However, this not only lowers the fuel consumption rate, but the fuel injected at this time causes the combustion chamber 3
It is accumulated without burning inside. Therefore, in order to prevent combustion from occurring, it is preferable to at least inhibit the fuel injection action.

The above-mentioned maximum allowable displacement DM is the engine body 1
The temperature may vary depending on, for example, the engine cooling water temperature THW or the engine oil temperature. In the example shown in FIG.
When the engine cooling water temperature THW is lower than the constant value T1, the threshold DD is maintained, and the engine cooling water temperature THW is maintained at the constant value T1.
When it exceeds 1, it increases as THW increases. This maximum allowable displacement DM is stored in advance in the ROM 32 in the form of the map shown in FIG.

Further, in the embodiment according to the present invention, when the starter motor switch 43 is turned on and D> DM, the hydraulic pressure control valve 67 is controlled to reduce the piston displacement amount D.

More specifically, when D> DM when the starter motor switch 43 is turned on, the hydraulic pressure control valve 67 is controlled to move the lift amount increasing chamber 65 through the return passage 71.
The lift amount reducing chamber 66 is connected to the oil pump 70. Oil pump 7 if the viscosity of the working oil is low
The working oil discharged from 0 flows into the lift amount reduction chamber 66, and the piston displacement amount D is reduced. Even if the viscosity of the working oil is high, the lift amount increasing chamber 65 is connected to the return passage 71, so that the piston displacement amount D is easily reduced. That is, as described above, the intake valve 6 is biased toward the cam 61, while the second cam crest 61b is inclined with respect to the cam axis M. Therefore, when the cam 61 is rotated around the cam axis M by cranking, the cam 61 is biased in a direction in which the piston displacement amount D decreases each time the intake valve 6 passes through the second cam crest 61b. become. At this time, if the lift amount increasing chamber 65 is connected to the return passage 71, the working oil in the lift amount increasing chamber 65 is likely to flow out of the lift amount increasing chamber 65, so that the piston displacement amount D is easily reduced.

Next, when D ≦ DM, the prohibition of the fuel injection action is released, that is, combustion is started. Therefore, the engine is substantially started, at which time a good engine start is ensured.

However, for example, the piston 64 is located in the hydraulic chamber 6
When fixed to No. 3, the piston displacement amount D as described above
However, the actual piston displacement amount D does not decrease even if the reduction effect is applied, and the engine cannot be started. Therefore, in the embodiment according to the present invention, even if the predetermined allowable time tM elapses after the starter motor switch 43 is turned on, D ≦
When DM does not occur, the fuel injection action is started, and it is determined that an abnormality has occurred in the intake valve drive device 7, and combustion is started using the abnormal condition parameter.

That is, the fact that D ≦ DM does not hold means that the burned gas in the combustion chamber 3 is returned to the combustion chamber 3 in an amount more than the allowable amount. Therefore, engine control parameters such as the opening degree of the throttle valve 17, the ignition timing, the fuel injection amount, or the fuel injection timing that allow the engine to start even when the burned gas in the combustion chamber 3 is returned to the combustion chamber 3 in an amount exceeding the allowable amount. Is previously determined as an abnormal time parameter by an experiment, and combustion is started with the abnormal time parameter.

On the other hand, the starter motor switch 43
When D is turned on when D ≦ DM, or the allowable time t
When D ≦ DM before M has elapsed, the intake valve drive device 7 is normal, and the engine control parameter used at this time can be referred to as a normal time parameter. This normal time parameter is an engine control parameter necessary for starting the engine favorably when D ≦ DM.

The allowable time tM may vary depending on the temperature of the engine body 1, for example, the engine cooling water temperature THW or the engine oil temperature. In the example shown in FIG. 7, the engine cooling water temperature T
It becomes shorter as HW increases. The allowable time tM is shown in FIG.
Are stored in the ROM 32 in advance in the form of the map shown in FIG.

That is, as shown in FIGS. 8 and 9, when the piston displacement amount D is larger than the maximum allowable displacement amount DM when the starter motor switch 43 is turned on,
The fuel injection action is prohibited (OFF), and the lift amount increasing chamber 65 is
Is connected to the return passage 71, and the lift amount reduction chamber 66 is connected to the oil pump 70. Next, as shown in FIG. 8, when D ≦ DM, the fuel injection action is started (ON) with the normal condition parameter, and the lift amount increasing chamber 65 and the lift amount decreasing chamber 66 are connected to the oil pump 70 and the return passage. Blocked from 71.

Alternatively, as shown in FIG. 9, if D> DM even after the permissible time tM has elapsed since the starter motor switch 43 was turned on, the fuel injection action is started (on) by the abnormal condition parameter. , Lift amount increase chamber 6
5 continues to be connected to the return passage 71, and the lift amount reduction chamber 66
Remains connected to the oil pump 70.

When it is determined that the intake valve driving device 7 is abnormal, the lift amount increasing chamber 65 is not exhausted even after the engine has been started.
Is preferably connected to the return passage 71, and the lift reduction chamber 66 is preferably connected to the oil pump 70.

FIG. 10 shows a routine for executing the above-described starting control. This routine is executed only once when the starter motor switch 43 is turned on.

Referring to FIG. 10, first, step 100
Then, the maximum allowable displacement DM of the piston displacement D is calculated from the map of FIG. In the following step 101, the allowable time tM is calculated from the map of FIG. Continued Step 10
In 2, the actual piston displacement amount D is read, and in the following step 103, the piston displacement amount D is the maximum allowable displacement amount DM.
Is determined to be greater than or equal to. If D> DM, then the routine proceeds to step 104, where fuel injection is prohibited.
In the following step 105, the lift amount increasing chamber 65 is connected to the return passage 71 and the lift amount decreasing chamber 66 is connected to the oil pump 7.
The hydraulic control valve 67 is controlled so as to be connected to 0. In the following step 106, it is determined whether or not the allowable time tM has elapsed since the starter motor switch 43 was turned on. When the permissible time tM has not elapsed, the process returns to step 102, and when the permissible time tM has elapsed, the process proceeds to step 107, and the fuel injection action is started under the abnormal condition parameter. Therefore, combustion is started. On the other hand, when D ≦ DM in step 103, the routine proceeds to step 108, and the fuel injection action is started under the normal condition parameter. Therefore, combustion is started.

In the embodiments described so far, the intake valve cam is formed of a single cam 61, and the cam 61 is provided with a first cam.
And the second cam ridges 61a and 61b.
However, the intake valve cam is formed of, for example, two cams, and only one of the first cam peaks 61a is formed on one of the cams.
It is also possible to form only the second cam crest 62b on the other cam.

Further, in the embodiments described so far, the burned gas is returned into the combustion chamber 3 by opening the intake valve 6 in the exhaust stroke. However, it is also possible to return the burnt gas from the exhaust port 11 into the combustion chamber 3 by opening the exhaust valve 9 in the intake stroke. In this case, an exhaust valve cam for opening and closing the exhaust valve 9 and a first cam crest for opening the exhaust valve 9 in the exhaust stroke,
A second cam crest that opens the exhaust valve 9 in the intake stroke is formed, and the lift amount of the exhaust valve 9 by the second cam crest can be changed so that the second cam crest is generated when the engine should be started. Combustion may be prevented from occurring when the lift amount of the exhaust valve is larger than a predetermined allowable amount.

[0047]

EFFECTS OF THE INVENTION Stable combustion can be obtained when the engine is started.

[Brief description of drawings]

FIG. 1 is an overall view of an internal combustion engine.

FIG. 2 is an overall view of an intake valve drive device.

FIG. 3 is a perspective view of an intake valve cam.

FIG. 4 is a diagram showing displacement amounts of an intake valve and an exhaust valve.

FIG. 5 is a diagram showing a lift amount of an intake valve due to a second cam lobe.

FIG. 6 is a diagram showing an allowable maximum displacement amount.

FIG. 7 is a diagram showing an allowable time.

FIG. 8 is a time chart for explaining an example according to the present invention.

FIG. 9 is a time chart for explaining an example according to the present invention.

FIG. 10 is a flowchart for executing start-time control.

[Explanation of symbols]

1 ... Engine body 4 ... Fuel injection valve 6 ... Intake valve 7 ... Intake valve drive device 61 ... Intake valve cam 61a ... 1st Kam mountain 61b ... Second Cam Mountain

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 45/00 362 F02D 45/00 362S 3G301 F02M 25/07 510 F02M 25/07 510B F term (reference) 3G016 AA08 AA19 BA34 BA36 BA39 DA01 DA06 GA07 3G018 AB17 BA04 CA19 DA03 EA17 EA18 EA21 EA22 EA31 EA32 EA35 FA06 FA16 FA23 GA09 GA11 3G062 AA00 BA04 CA01 DA02 GA00 GA08 GA16 GA10 FA02 FA33 FA11 FA10 FA33 FA11 FA10 FA33 FA10 FA10 FA33 FA10 FA10 FA33 FA10 FA10 FA33 FA10 FA33 FA10 FA33 FA10 FA10 FA33 FA10 FA10 FA10 FA10 FA33 FA10 FA10 FA10 FA10 FA33 FA10 FA33 FA11 FA10 FA33 FA10 FA33 FA11 FA33 FA11 FA10 FA10 FA10 FA33 FA10 FA33 DA04 DA06 EA08 EA11 EA16 EA17 EC09 FA31 GA01 HA05Z HA12Z HE01Z HE08Z HF09Z HF19Z 3G301 HA01 HA19 HA00 JA00 KA01 LA07 LB01 MA11 NA08 NC02 NE23 PA07Z PE01Z PE08Z PE10Z PF03Z PF16Z

Claims (8)

[Claims] 1. An intake valve or an exhaust valve, comprising lift amount varying means capable of changing a lift amount of an intake valve or an exhaust valve, which is obtained in a state of the lift amount varying means at this time when an engine is to be started. A starting control device for an internal combustion engine, which determines whether or not a lift amount is outside a predetermined allowable range, and prevents combustion from occurring when it is determined that the lift amount is outside the allowable range. 2. The internal combustion engine according to claim 1, wherein combustion is prevented by prohibiting a fuel supply action to the engine when it is determined that the lift amount is out of an allowable range. Start control device. 3. A cam for opening and closing the intake valve comprises a first cam crest for opening the intake valve in an intake stroke, and a second cam crest for opening the intake valve in an exhaust stroke. The lift amount varying means can change the lift amount of the intake valve by the second cam crest, and the lift amount of the intake valve by the second cam crest is larger than a predetermined allowable amount when the engine is to be started. The start control system for an internal combustion engine according to claim 1, wherein combustion is sometimes prevented. 4. A cam for opening and closing the exhaust valve comprises a first cam crest for opening the exhaust valve in the exhaust stroke and a second cam crest for opening the exhaust valve in the intake stroke. The lift amount varying means can change the lift amount of the exhaust valve by the second cam crest, and the lift amount of the exhaust valve by the second cam crest is larger than a predetermined allowable amount when the engine should be started. The start control system for an internal combustion engine according to claim 1, wherein combustion is sometimes prevented. 5. The second cam lobes are movably held in the cam axis direction, and when the second cam lobes are moved in the cam axis direction, an intake valve or an exhaust gas by the second cam lobes is provided. The second cam lobe is shaped so that the lift amount of the valve is changed, and the position of the second cam lobe in the cam axis direction when the engine is to be started is detected and the intake valve or The start control device for an internal combustion engine according to claim 3 or 4, which determines whether or not the lift amount of the exhaust valve is larger than an allowable amount. 6. A return means for controlling the lift amount varying means so that the lift amount falls within an allowable range when it is determined that the lift amount falls outside the allowable range.
A starting control device for an internal combustion engine according to item 1. 7. When the lift amount is determined to be outside the allowable range, a cranking action is performed while preventing combustion from occurring, and a predetermined allowable time elapses after the cranking action is started. 7. The start control device for the internal combustion engine according to claim 6, wherein even if it is determined that the lift amount is out of the allowable range, combustion is started based on a predetermined abnormal condition parameter. 8. The start control device for an internal combustion engine according to claim 6, wherein combustion is started based on a predetermined normal time parameter when the lift amount is within an allowable range by the returning means. .