JP2015218631A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a desired lift amount of an exhaust valve even if stop time of an internal combustion engine is relatively long.SOLUTION: An internal combustion engine control device comprises: a decompression device 50 releasing a cylinder internal compression pressure; and a control unit configured to control the decompression device 50. The decompression device 50 includes an exhaust valve 9; a valve spring 51; a rocker arm 52; a hydraulic lash adjuster (HLA) 53; a cam member 59 capable of selectively lifting the HLA 53 to an opening side of the exhaust valve 9; and a decompression-device actuator driving the cam member 59. The control unit activates the decompression-device actuator to lift the HLA 53 so as to always open the exhaust valve 9 at a time of starting an internal combustion engine. The control unit increases a lift amount of the HLA 53 at a time of restarting the internal combustion engine if stop time from stop to restart of the internal combustion engine exceeds predetermined time, from the lift amount if the stop time does not exceed the predetermined time.

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine provided with a decompression device for releasing in-cylinder compression pressure.

  An internal combustion engine having a decompression device (or a decompression device) that communicates an in-cylinder combustion chamber with an exhaust passage in order to release in-cylinder pressure at least during a compression stroke is known. Such a decompression device is used for the purpose of suppressing vibration noise and rotation fluctuation of the internal combustion engine when the internal combustion engine is stopped or started, and reduces the compression load and thus the load of the starting motor when starting the internal combustion engine, thereby reducing battery power consumption. It is used for the purpose of suppressing etc.

  Patent Document 1 discloses a configuration in which an exhaust valve of an internal combustion engine is used in order to selectively bring the in-cylinder combustion chamber and the exhaust passage into a communication state (open) or a non-communication state (close). In this configuration, a rocker arm that drives the exhaust valve and a hydraulic lash adjuster that forms the rocking center of the rocker arm are provided, and the exhaust valve is lifted by a desired amount by lifting the hydraulic lash adjuster. .

JP 2007-024030 A

  By the way, in the structure of the decompression device provided with the hydraulic lash adjuster as seen in Patent Document 1, when the stop time from the stop to the restart of the internal combustion engine is relatively long, the interior of the hydraulic lash adjuster There is a problem that the oil leaks and decreases, and a desired lift amount of the exhaust valve may not be obtained when the internal combustion engine is restarted.

  Accordingly, the present invention has been made in view of the above circumstances, and its purpose is to obtain a desired lift amount of the exhaust valve even when the stop time from the stop to the restart of the internal combustion engine is relatively long. Another object of the present invention is to provide a control device for an internal combustion engine.

According to one aspect of the invention,
A decompression device for communicating the in-cylinder combustion chamber with the exhaust passage in order to release the in-cylinder pressure at least during the compression stroke;
A control unit configured to control the decompression device;
With
The decompression device includes an exhaust valve that opens and closes the exhaust passage, a valve spring that biases the exhaust valve in a closing direction, a rocker arm that receives a driving force from a camshaft and operates the exhaust valve in an opening direction. A hydraulic lash adjuster that forms the rocking center of the rocker arm, a cam member that can selectively lift the hydraulic lash adjuster to the open side of the exhaust valve, and a decompression actuator that drives the cam member.
The control unit operates the decompression actuator to lift the hydraulic lash adjuster so that the exhaust valve is always opened when the internal combustion engine is started.
The control unit is configured such that when the stop time from the stop to restart of the internal combustion engine exceeds a predetermined time, the hydraulic lash adjuster at the time of restart is compared with a case where the stop time does not exceed the predetermined time. A control apparatus for an internal combustion engine characterized by increasing a lift amount is provided.

  According to the present invention, even when the stop time from the stop to the restart of the internal combustion engine is relatively long, an excellent effect that the desired lift amount of the exhaust valve can be obtained is exhibited.

It is the schematic which shows the structure of the internal combustion engine which concerns on embodiment of this invention, and its control apparatus. It is an expanded front sectional view of a decompression device. It is an expanded side sectional view of a decompression device. It is a time chart which shows the change of the lift amount of an intake valve and an exhaust valve, the intake flow rate, and the exhaust flow rate at the time of non-operation of a decompression device. It is a time chart which shows the change of the lift amount of an intake valve and an exhaust valve, the intake air flow rate, and the exhaust gas flow rate at the time of operation of a decompression device. It is the schematic which shows a comparative example and its operation | movement. It is a graph which shows the relationship between an engine stop time and the contraction amount of a hydraulic lash adjuster. It is the schematic which shows each position of a decompression cam. It is a flowchart which shows the routine of the switching process of the operation position at the time of the action | operation of a decompression apparatus. It is a flowchart which shows the routine of start control. The map of lift correction amount (DELTA) in other embodiment is shown. It is a flowchart which shows the routine of the switching process of the operation position in other embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 schematically shows the configuration of an internal combustion engine and its control device according to this embodiment. An internal combustion engine (engine) 1 according to the present embodiment is mounted on a vehicle and is configured as a multi-cylinder (for example, in-line 4-cylinder) spark ignition internal combustion engine. However, the type of engine, the number of cylinders, the cylinder arrangement type (in-line, V-type, horizontally opposed, etc.), the ignition method, etc. are not particularly limited. For example, the engine may be a compression ignition type internal combustion engine (diesel engine). The type and application of the vehicle are not particularly limited. For example, the vehicle may be a normal vehicle having the engine 1 as a sole power source, or a hybrid vehicle having two power sources of the engine 1 and an electric motor. There may be. The vehicle is provided with an electronic control unit (hereinafter referred to as ECU) 20 as a control unit configured to control the vehicle and the engine.

  A piston 3 is accommodated in a cylinder (cylinder) 2 a formed in a cylinder block 2 of the engine 1 so as to be able to reciprocate. A crankshaft 4 is connected to the piston 3. The cylinder head 5 of the engine 1 is provided with two intake valves 7 for opening and closing the intake port 6 and two exhaust valves 9 for opening and closing the exhaust port 8 for each cylinder. Each intake valve 7 and each exhaust valve 9 are driven to open and close by a valve operating mechanism including camshafts 10 and 11. The camshafts 10 and 11 are connected to the crankshaft 4 through a power transmission mechanism. A spark plug 13 for igniting the air-fuel mixture in the in-cylinder combustion chamber 12 is attached to the top of the cylinder head 5 for each cylinder. A variable valve mechanism (for example, a variable valve timing mechanism) for changing the opening characteristic of at least one of the intake valve 7 and the exhaust valve 9 may be provided.

  The intake port 6 of each cylinder is connected to a surge tank 15 that is an intake manifold through an intake manifold or branch pipe 14 for each cylinder. An intake pipe 16 is connected to the upstream side of the surge tank 15, and an air cleaner (not shown) is provided at the upstream end of the intake pipe 16. An air flow meter 17 for detecting the intake air amount and an electronically controlled throttle valve 18 are incorporated in the intake pipe 16 in order from the upstream side. An intake passage is formed by the intake port 6, the branch pipe 14, the surge tank 15, and the intake pipe 16. An injector 19 for injecting fuel into the intake passage, particularly the intake port 6 is provided for each cylinder.

  An exhaust manifold and an exhaust pipe (not shown) are connected to the exhaust port 8 of each cylinder, and a catalyst composed of a three-way catalyst is installed in the exhaust pipe. Upstream and downstream air-fuel ratio sensors for detecting the air-fuel ratio of exhaust gas are installed upstream and downstream of the catalyst. The ECU 20 executes air-fuel ratio feedback control for controlling each air-fuel ratio to stoichiometric (theoretical air-fuel ratio) based on the outputs of these air-fuel ratio sensors.

  Regarding the sensors, in addition to the air flow meter 17 and the upstream and downstream air-fuel ratio sensors described above, a crank angle sensor 35 for detecting the crank angle of the engine 1, an accelerator opening sensor 36 for detecting the accelerator opening, A water temperature sensor 37 for detecting the coolant temperature of the engine 1 is electrically connected to the ECU 20. A start switch 39 for starting or stopping the engine 1 is electrically connected to the ECU 20. The ECU 20 controls the spark plug 13, the throttle valve 18, and the injector 6 based on the detection values of these sensors. The ignition timing, fuel injection amount, fuel injection timing, throttle opening, etc. are controlled.

  In addition, in the engine 1 of the present embodiment, a decompression device (or a decompression device) 50 that communicates the in-cylinder combustion chamber 12 with the exhaust passage (exhaust port 8) in order to release the in-cylinder pressure at least during the compression stroke of the engine. Is provided.

  Hereinafter, the decompression device 50 will be described with reference to FIGS. 2 and 3. The decompression device 50 of the present embodiment is configured to release at least the in-cylinder pressure, that is, the compression pressure during the compression stroke, by lifting (opening) the exhaust valve 9 of the engine 1 by a certain amount. Therefore, the decompression device 50 of this embodiment uses the exhaust valve 9 as a part of the constituent elements.

  As illustrated, the cylinder head 5 includes an exhaust camshaft 11 (camshaft), an exhaust valve spring 51 (valve spring), a rocker arm 52, and a hydraulic lash adjuster (components of a valve mechanism for the exhaust valve 9). (Hereinafter referred to as HLA) 53 is provided. The exhaust valve spring 51, the rocker arm 52, and the HLA 53 are provided for each exhaust valve 9. The valve operating mechanism for the intake valve 7 is configured in the same manner, and corresponding parts are represented in FIG.

  The exhaust valve spring 51 urges the exhaust valve 9 in the closing direction. The rocker arm 52 swings in response to the driving force from the exhaust camshaft 11 and selectively operates the exhaust valve 9 in the opening direction. In the present embodiment, the exhaust camshaft 11 is in direct contact with the rocker arm 52, and the exhaust camshaft 11 directly drives the rocker arm 52. However, an intermediate member such as a roller arm may be interposed between the exhaust camshaft 11 and the rocker arm 52 so that the exhaust camshaft 11 drives the rocker arm 52 via the intermediate member.

  As is well known, the HLA 53 forms the rocking center of the rocker arm 52 and operates so as to always eliminate the clearance between the exhaust camshaft 11 (or the intermediate member) and the rocker arm 52. Although not described in detail, the HLA 53 includes an HLA main body 53A and a plunger 53B that protrudes upward from the HLA main body 53A and can move up and down in the HLA main body 53A. As a result, the entire HLA 53 can be expanded and contracted. Oil or hydraulic pressure is supplied through the oil passage 55 into the HLA 53, that is, into the HLA main body 53A and the plunger 53B. Such supply is performed by an oil pump (not shown) that is rotationally driven by the crankshaft 4.

  The exhaust camshaft 11, the exhaust valve spring 51, the rocker arm 52, and the HLA 53 constitute constituent elements of the decompression device 50. In addition to these, the decompression device 50 includes a decompression cam shaft 59 as a cam member that can selectively lift the HLA 53 to the open side of the exhaust valve 9, and a decompression actuator 57 that drives the decompression cam shaft 59.

  The decompression cam shaft 59 is a single member common to all cylinders, and is rotatably inserted into the cam shaft insertion hole 60 and supported. The camshaft insertion hole 60 is formed in the cylinder head 5 so as to face the bottom of each HLA 53. The decompression cam shaft 59 has a decompression cam 59A disposed so as to contact the bottom surface of each HLA 53. When the decompression cam 59A is rotated by the rotation of the decompression cam shaft 59, the HLA 53 is raised and lowered. In addition, the HLA 53 is supported in the HLA support hole 61 formed in the cylinder head 5 so as to be movable up and down. The decompression cam shaft 59 is rotationally driven by an electric decompression actuator 57.

  The decompression actuator 57 is electrically connected to the ECU 20 and controlled by the ECU 20. An on / off signal and a signal indicating the target displacement amount of the decompression actuator 57 are sent from the ECU 20 to the decompression actuator 57, and a signal showing the actual displacement amount of the decompression actuator 57 is sent from the decompression actuator 57 to the ECU 20.

  When the decompression device 50 is operated, the decompression actuator 57 is turned on, and the decompression actuator 57 is rotationally displaced by an amount equal to the target displacement amount, so that the decompression cam shaft 59 operates 180 ° different from the stop position shown in FIGS. Rotate to position (shown in phantom line in FIG. 3). Then, the decompression cam 59A directly pushes up the HLA 53 and lifts it upward. As a result, the rocker arm 52 rotates and lifts the exhaust valve 9 in the opening direction (downward). Such an operation is performed simultaneously for each exhaust valve 9. As a result, the same effect as the enlargement of the base circle of the exhaust camshaft 11 can be obtained, and each exhaust valve 9 is not fully closed, but is lifted at least by a minute amount much smaller than the lift amount when fully opened.

  The stop position and the operating position of the decompression cam shaft 59 shown in FIGS. 2 and 3 are not the stop position and the operating position employed in this embodiment. The stop position and the operation position will be described later.

  The HLA 53 is extended to eliminate the clearance between the exhaust camshaft 11 and the rocker arm 52 when hydraulic pressure is supplied from the oil pump during engine operation. When the decompression device 50 is operated in this state, the exhaust valve 9 is lifted by at least the minimum decompression lift amount Ldmin. The minimum decompression amount Ldmin is, for example, 1 mm, but the value can be arbitrarily determined.

  Here, when the engine is started or stopped, the hydraulic pressure supply from the oil pump is insufficient or completely absent, and the engine speed is also low. Electric type is used instead of hydraulic type. In addition, the decompression device 50 of the present embodiment is configured using the components of the exhaust valve and the valve operating mechanism, which is very advantageous for cost reduction.

  4 and 5 show changes in the lift amount ((A) diagram) of the intake valve 7 and the exhaust valve 9 and the intake flow rate and exhaust flow rate ((B) diagram) in a specific cylinder. 4 shows the decompression device 50 when it is not operating, and FIG. 5 shows the decompression device 50 when it is operating. In FIG. 5B, the intake flow rate is positive in the direction flowing into the in-cylinder combustion chamber 12, and the exhaust flow rate is positive in the direction flowing out from the in-cylinder combustion chamber 12. 4 and 5 show data when the engine is motored at 1000 rpm.

  As can be seen from FIG. 5, the exhaust valve 9 is always open when the decompression device 50 is operated, and the exhaust valve 9 is also closed (see FIG. 4) when the decompression device 50 is closed (the lift amount is zero). 9 is lifted by a predetermined minimum decompression lift amount Ldmin. Thus, the in-cylinder combustion chamber 12 is always in communication with the exhaust passage (particularly the exhaust port 8). The minimum decompression lift amount Ldmin defines the minimum lift amount of the exhaust valve 9 when the decompression device 50 is operated. At the timing when the exhaust valve 9 is open (the lift amount is not zero) when the decompression device 50 is not in operation (see FIG. 4), the lift amount of the exhaust valve 9 when the decompression device 50 is activated is the decompression device. It is a value obtained by adding the minimum decompression lift amount Ldmin to the lift amount at the time of non-operation of 50.

  The decompression device 50 of the present embodiment is activated when the engine is started. That is, the ECU 20 lifts the HLA 53 by operating the decompression actuator 57 so that the exhaust valve 9 is always opened when the engine is started. As a result, vibration noise and rotational fluctuations at the time of starting the engine can be suppressed, and the compression load and thus the load on the starting motor can be reduced, thereby suppressing battery power consumption, fuel consumption, and the like.

  By the way, in the configuration of the decompression device 50 including the HLA 53 as in the present embodiment, when the stop time from the engine stop to the restart is relatively long, the oil inside the HLA 53 leaks and decreases. There is a problem that a desired amount of lift of the exhaust valve 9 may not be obtained when the engine is restarted.

  This problem will be described with reference to a comparative example shown in FIG. Note that FIG. 6 is a diagram in which the shape, dimensions, scale, arrangement, and the like are deformed in order to make the operation of each member easy to understand, and it should be noted that it is different from the actual shape shown in FIGS.

  When the engine is stopped and the crankshaft is also stopped rotating, the rotational phase position of the exhaust camshaft 11 in the stopped state and the open state of the exhaust valve 9 vary depending on the cylinder and the rotation stop timing. Here, as an easy-to-understand example, FIGS. 6 (A) and 6 (B) show an example (cylinder) in which the exhaust valve 9 is completely closed in an engine stop state (also a rotation stop state of the crankshaft). FIGS. 6C to 6F show examples (cylinders) in which the exhaust valve 9 is fully opened (maximum lift) when the engine is stopped.

  As shown in FIG. 6A, when the engine is stopped and the decompression device is stopped, the exhaust camshaft 11 is in contact with the rocker arm 52 at the base circle position a1 and substantially pushes down the rocker arm 52 and the exhaust valve 9. Absent. Therefore, the reaction force from the exhaust valve spring 51 does not act on the rocker arm 52, and the rocker arm 52 does not push down the plunger 53B of the HLA 53. Therefore, the HLA 53 is not subjected to a force that contracts the HLA 53 (presses the plunger 53B into the HLA main body 53A) and leaks oil from the inside of the HLA 53.

  Assume that there is no oil leak from the HLA 53 and the decompression device is operated while the engine is stopped as shown in FIG. 6B while the HLA 53 remains in the same extended state. In this case, the decompression cam 59A is rotated and the HLA 53 is lifted by the lift amount Lh1. Then, the rocker arm 52 is rotated about the contact point with the exhaust camshaft 11 to push down the exhaust valve 9 and lift the exhaust valve 9 by the minimum decompression lift amount Ldmin. This is the desired operating state with no problems.

  However, as shown in FIG. 6C, when the exhaust camshaft 11 is stopped at a rotational phase position where the exhaust valve 9 is fully opened (lift amount = Lmax) in the engine stopped state and the decompression device stopped state. Is a problem. That is, in this case, the exhaust camshaft 11 is in contact with the rocker arm 52 at the maximum lift position a2, and pushes down the rocker arm 52 and the exhaust valve 9 to the maximum lift Lmax against the reaction force from the exhaust valve spring 51. Accordingly, a reaction force from the exhaust valve spring 51 acts on the rocker arm 52, and the rocker arm 52 pushes down the plunger 53B of the HLA 53. Accordingly, the HLA 53 is subjected to a force that contracts the HLA 53 and leaks oil from the inside of the HLA 53.

  If left in this state, as shown in FIG. 6D, the oil gradually leaks from the inside of the HLA 53 to the oil passage 55 and eventually to the oil pump side, and the HLA 53 gradually contracts (leaks down or sinks). Also called). The illustrated example shows a state in which the HLA 53 has finally contracted to the maximum (a state with a bottom). Accordingly, the rocker arm 52 is pushed back in the valve closing direction of the exhaust valve 9 and rotates, and the lift amount of the exhaust valve 9 decreases. In recent years, oil leaks from the HLA 53 tend to decrease, and if the duration of such a pressing state is within a predetermined time, no oil leakage will be caused. However, if the pressing state continues beyond such a predetermined time, A problem oil leak occurs, and the above-described exhaust valve lift amount decreases.

  Next, when the decompression device is operated in this state, the decompression cam 59A is rotated as shown in FIG. 6E, and the HLA 53 is lifted by the lift amount Lh1. Then, the exhaust valve 9 is lifted by a lift amount corresponding to the lift amount Lh1.

  However, from this state, it is assumed that cranking has been executed for engine start with decompression operation. Then, as shown in FIG. 6 (F), the exhaust camshaft 11 is rotated, and the rocker arm 52 swings with the contact portion with the HLA 53 as the swing center following the rotation. During this time, the exhaust camshaft 11 sometimes contacts the rocker arm 52 at a lift position lower than the maximum lift position a2, for example, at the base circle position a1. At this time, the exhaust valve 9 must be lifted by the minimum decompression lift amount Ldmin. However, since the HLA 53 has already contracted, the position of the oscillation center is shifted downward from the original position as shown in FIG. 6B, and as a result, the lift amount of the HLA 53 is substantially reduced. The same result is caused, and there arises a problem that the lift amount of the exhaust valve 9 is insufficient and the desired minimum decompression lift amount Ldmin cannot be obtained. As a result, only a decompression amount smaller than the minimum decompression amount Ldmin can be obtained.

  This problem may occur not only when the exhaust camshaft 11 is stopped at the rotational phase position corresponding to the fully open state of the exhaust valve 9 while the engine is stopped and the decompression device is stopped. That is, this problem can occur when the rocker arm 52 receives a force from the exhaust valve 9. This is because in this case, the force also acts on the HLA 53 to cause the HLA 53 to contract. Therefore, the above problem can occur when the exhaust camshaft 11 is stopped at the rotational phase position where the exhaust valve 9 is lifted. Further, although the exhaust valve 9 is not lifted, the exhaust camshaft 11 is stopped at the rotational phase position where the rocker arm 52 receives the force from the exhaust valve 9 below the set load of the exhaust valve spring 51 (excluding zero). The above-mentioned problem may occur even if it is done. The set load of the exhaust valve spring 51 is a load required to compress the exhaust valve spring 51 when the exhaust valve spring 51 is attached. The exhaust valve 9 is not lifted unless a force exceeding the set load is applied.

  As can be seen from the above description, when the engine is stopped with the HLA 53 receiving a force in the contraction direction and the stop time from the stop to the restart is relatively long, the exhaust valve 9 The desired amount of lift may not be obtained. In the case of a multi-cylinder engine, it is considered that the HLA 53 receives a force in the contraction direction while the engine is stopped in any of the cylinders.

  FIG. 7 shows the relationship between the stop time from the engine stop (horizontal axis) and the HLA contraction amount (vertical axis). A solid line a indicates a case where the exhaust camshaft 11 is stopped at the rotational phase position corresponding to the fully opened exhaust valve 9 when the engine is stopped (fully opened cylinder). A broken line b shows a case where the exhaust camshaft 11 is stopped at a rotational phase position corresponding to the fully closed state of the exhaust valve 9 (fully closed cylinder) when the engine is stopped. In the case of the broken line b, a relatively weak force greater than zero and less than or equal to the set load of the valve spring 51 is applied to the rocker arm 52 from the exhaust valve 9, and the HLA is contracted due to this force.

  As shown in the figure, in the case of a fully opened cylinder, the HLA contraction starts earlier, the HLA contraction speed is fast, and reaches the maximum contraction amount Smax (the contraction amount when the HLA bottoms out) compared to the fully closed cylinder. It's too early. This is because the HLA 53 receives a greater force in the contraction direction in the fully open cylinder than in the fully closed cylinder. From this figure, it will be understood that as the lift amount of the exhaust valve 9 when the engine is stopped increases from zero, the characteristics of the fully closed cylinder approach the characteristics of the fully opened cylinder.

  Therefore, in order to solve the above problem, in the present embodiment, when the stop time from the stop of the engine to the restart exceeds a predetermined time, the HLA 53 at the time of restart is compared with a case where the stop time does not exceed the predetermined time. Increase the lift amount. Such increase is performed by the ECU 20.

  More specifically, as shown in FIG. 8, the decompression cam 59A has a stop position P0 as shown in (A), a first operating position P1 as shown in (B), and as shown in (C). It is located at any one of the second operating positions P2. Thus, in addition to the stop position, two stages of operation positions are defined.

  The stop position P0 is a position when the decompression device 50 is stopped. On the other hand, as will be described in detail later, the first operating position P1 is a position when the decompression device 50 is operating, and when the HLA contraction amount is zero or relatively small, a desired value of the exhaust valve 9 is obtained. The position is such that the minimum decompression lift amount Ldmin can be obtained. The second operating position P1 is a position when the decompression device 50 is operating, and is a position where the desired minimum decompression lift amount Ldmin of the exhaust valve 9 can be obtained when the HLA contraction amount is relatively large. is there.

  The decompression cam 59A is rotated in the rotation direction R around the rotation center axis C as it goes in order from the stop position P0 to the first operation position P1 and the second operation position P2. When the decompression cam 59A is at the stop position P0, the decompression cam 59A contacts the HLA 53 at the point Q0. The angular position θ (°) of the decompression cam 59A at this point Q0 is set as a reference angular position θ0 (= 0 °).

  When the decompression cam 59A is rotated in the rotation direction R by the first angle Δθ1 from the stop position P0, the decompression cam 59A reaches the first operating position P1. In the illustrated example, the first angle Δθ1 is 45 °, but this value can be arbitrarily changed. In the first operating position P1, the decompression cam 59A contacts the HLA 53 at the point Q1.

  When the decompression cam 59A is rotated in the rotation direction R by the second angle Δθ2 from the stop position P0, the decompression cam 59A reaches the second operation position P2. The second angle Δθ2 is larger than the first angle Δθ1, and in the illustrated example, the second angle Δθ2 is 90 °, but this value can be arbitrarily changed. In the second operating position P2, the decompression cam 59A contacts the HLA 53 at the point Q2.

  As the decompression cam 59A is sequentially rotated from the stop position P0 to the first operation position P1 and the second operation position P2, the lift amount of the HLA 53 is increased in order to the first lift amount Lh1 and the second lift amount Lh2.

  When the decompression device is operated upon engine restart, the ECU 20 determines that the decompression cam 59A is at the first operating position P1 when the engine stop time T before the restart does not exceed the predetermined time Ts (T ≦ Ts). The decompression actuator 57 is rotationally displaced so that it is positioned, and the decompression cam shaft 59 is rotated. As a result, the HLA 53 is lifted by the first lift amount Lh1. Further, when the engine stop time T exceeds the predetermined time Ts (T> Ts), the ECU 20 rotationally displaces the decompression actuator 57 so that the decompression cam 59A is positioned at the second operating position P2, and the decompression cam shaft 59 Rotate. As a result, the HLA 53 is lifted by the second lift amount Lh2.

  In particular, when the engine stop time T exceeds the predetermined time Ts, the lift amount of the HLA 53 is increased more than the first lift amount Lh1, so the engine stop time T is relatively long and the HLA 53 is oil leaked as described above. Even in the case of contraction, the lift amount of the HLA 53 can be increased so as to compensate for this contraction. Therefore, the desired minimum decompression amount Ldmin of the exhaust valve 9 can be obtained.

  Regarding the profile of the decompression cam 59A shown in FIG. 8, the decompression cam 59A has the minimum reference radius r0 at the reference angular position θ0 = 0 °, and the second angular position θ2 = 90 ° corresponding to the point Q2 (counter rotation direction). The maximum second radius r2. The angular position range of about 180 ° to about 360 ° has a reference radius r0 that defines the base circle of the decompression cam 59A.

  The decompression cam 59A gives the first lift amount Lh1 of the HLA 53 when in the first operating position P1. This first lift amount Lh1 is equal to the lift amount Lh1 at the operating position as shown in (B) and (E) of the comparative example of FIG. That is, in the present embodiment, the lift amount Lh2 larger than that of the comparative example can be given to the HLA 53 at the second operating position P2. Thus, the HLA 53 can be lifted more greatly so as to compensate for the contraction of the HLA 53 and to obtain the minimum decompression lift amount Ldmin of the exhaust valve 9.

  2 and 3 and FIG. 8, in the example of FIGS. 2 and 3, the angle position of θ = 270 ° (indicated by the point Q3 in FIG. 8) corresponds to the stop position, and θ = θ2 An angular position of = 90 ° corresponds to the operating position. However, when this is done, when the decompression cam 59A is rotated from the stop position to the operating position, the base circle portion without any lift of the HLA 53 is forced to move 90 ° (from 270 ° to about 360 °). Such invalid movement causes unnecessary operation of the decompression actuator 57 and wastes battery power. On the other hand, in this embodiment, as shown in FIG. 8, when the decompression cam 59A is rotated from the stop position toward the operating position, the lift of the HLA 53 starts immediately. There is no invalid movement of the base circle part as described above. Therefore, useless operation of the decompression actuator 57 can be suppressed, and battery power can be used efficiently. Specifically, the reference angular position θ0 is set near the end point in the counter-rotation direction of the base circle portion of the decompression cam 59A.

  However, if the invalid movement can be allowed, the reference angular position θ0 can be arbitrarily set, and can be set to an angular position of θ = 270 ° as shown in FIGS.

  The predetermined time Ts for switching between the first operating position P1 and the second operating position P2 is set in consideration of the characteristics shown in FIG. In the present embodiment, for example, in consideration of the characteristics of a: fully opened cylinder in which HLA is most easily contracted, the stop time T2 in which the HLA contraction amount is approximately ½ of the maximum contraction amount Smax in the characteristics, It is set as the predetermined time Ts. T2 is, for example, 3 hours. A setting method other than this method is also possible.

  If the engine stop time T does not exceed the predetermined time Ts, the lift amount of the HLA 53 is controlled to the first lift amount Lh1 as a reference value, assuming that the contraction amount of the HLA 53 is relatively small. On the contrary, if the engine stop time T exceeds the predetermined time Ts, the HLA 53 is controlled to have a larger second lift amount Lh2 because the amount of contraction of the HLA 53 is relatively large. In any case, it is possible to obtain a desired minimum decompression amount Ldmin of the exhaust valve 9.

  Next, a routine executed by the ECU 20 will be described. FIG. 9 shows a routine for switching the operation position when the decompression device 50 is operated. This routine is repeatedly executed by the ECU 20 every predetermined calculation cycle.

  First, in step S101, the value of the engine stop time T calculated separately by the ECU 20 is acquired. This calculation may be performed by counting the elapsed time from the previous engine stop with a timer while the engine is stopped, or by subtracting the time at the previous engine stop from the current time.

  Next, in step S102, the acquired value of the engine stop time T is compared with a predetermined time Ts.

  When the engine stop time T does not exceed the predetermined time Ts, the operation position of the decompression cam 59A is set to the first operation position P1 in step S103. When the engine stop time T exceeds the predetermined time Ts, the operating position of the decompression cam 59A is set to the second operating position P2 in step S104.

  FIG. 10 shows a start control routine for starting the engine. This routine is also repeatedly executed by the ECU 20 every predetermined calculation cycle.

  In step S201, it is determined whether there is an engine start request. In this embodiment, when the start switch 39 is turned on to turn on the starter that is a starter motor, it is determined that there is a request for starting the engine. The determination may be made according to other conditions.

  If it is determined that there is no start request, the routine is terminated. If it is determined that there is a start request, the routine proceeds to step S202 where the starter is turned on and the engine is cranked.

  In step S203, the actual engine speed Ne calculated from the output of the crank angle sensor 35 is compared with a predetermined decompression completion speed Ne (for example, 400 rpm).

  When the engine speed Ne is lower than the decompression end rotation speed Nes, the routine proceeds to step S204, where the fuel cut (F / C) flag is turned on, and fuel injection from the injector 19 is prohibited. In step S205, the ignition flag is turned off, and ignition by the spark plug 13 is also prohibited.

  Next, in step S206, the decompression flag is turned on. Then, first, in step S207, the operating position determined in the routine of FIG. 9 is acquired, and then in step S208, the decompression device 50 is operated so that the actual operating position of the decompression cam 59A becomes the acquired operating position. .

  Thus, since the decompression operation is executed at the initial stage of cranking of the engine, the in-cylinder compression pressure is released, the load on the starter is reduced, and battery power consumption and the like can be suppressed. Further, vibration noise and rotation fluctuation of the engine can be suppressed. Furthermore, since the engine speed rises quickly, the starting time can be shortened and the starter capacity can be reduced to reduce the cost.

  On the other hand, if it is determined in step S203 that the engine rotational speed Ne is equal to or higher than the decompression completion rotational speed Ne, the routine proceeds to step S209, where the fuel cut flag is turned off, and the fuel injection prohibited state is released. In step S210, the ignition flag is turned on, and the ignition inhibition state is also released.

  Next, in step S211, the decompression flag is turned off. Then, in step S212, the decompression device 50 is stopped, and the decompression cam 59A is returned to the stop position.

  Finally, in step S213, an injection signal is set for the intake stroke cylinder, and preparation for subsequent fuel injection and thus substantial starting of the engine is made.

  Thus, after the engine speed Ne reaches the decompression end rotational speed Ne, fuel injection and ignition are performed as usual with the decompression device 50 stopped, and the engine is started.

  Next, another embodiment of the present invention will be described.

  In the basic embodiment described above, when the engine stop time exceeds a predetermined time, the lift amount of the HLA 53 is a second value obtained by adding a constant value ΔLh2 (see FIG. 8) to the first lift amount Lh1 as a reference value. The lift amount was uniformly controlled to Lh2. On the other hand, in this embodiment, when the engine stop time exceeds a predetermined time, the lift amount of the HLA 53 is variably controlled in a stepless manner or in multiple steps according to the stop time.

  FIG. 11 shows a map of the lift correction amount ΔLh added to the first lift amount Lh1. This map is stored in the ECU 20 in advance. As shown in the figure, this map defines the relationship between the engine stop time T and the lift correction amount ΔLh, and this relationship corresponds to the characteristic of a: fully opened cylinder shown in FIG. In the range of 0 ≦ T ≦ T1, the lift correction amount ΔLh is zero, and in the range of T1 <T <T3, the lift correction amount ΔLh increases steplessly and proportionally as the engine stop time T increases, and T ≧ T3 In the range, the lift correction amount ΔLh is a constant value ΔLh2. It will be understood that the stepless characteristics as shown in the range of T1 <T <T3 can be easily changed to similar multistage characteristics. T1 is, for example, 30 minutes and T3 is, for example, 6 hours, but these values can be arbitrarily changed. A function or the like may be used instead of the map.

  The predetermined time Ts is set equal to T1. When the engine stop time T does not exceed the predetermined time Ts, the lift amount of the HLA 53 is controlled to the first lift amount Lh1. When the engine stop time T exceeds the predetermined time Ts, the lift amount of the HLA 53 is controlled to a value obtained by adding the lift correction amount ΔLh (> 0) determined from the map to the first lift amount Lh1. Thus, when the stop time T exceeds the predetermined time Ts, the lift amount of the HLA at the time of restart is increased compared to the case where the stop time T does not exceed the predetermined time Ts.

  Regarding more specific operation, when the engine stop time T does not exceed the predetermined time Ts, the decompression cam 59A is controlled to the first operation position P1 shown in FIG. 8B.

  When the engine stop time T exceeds the predetermined time Ts (= T1), the decompression cam 59A is between the first operation position P1 shown in FIG. 8B and the second operation position P2 shown in FIG. 8C. Thus, the position is controlled steplessly at a position corresponding to the engine stop time T. Naturally, the position at this time is such a position that the above-described lift amount of the HLA 53 is realized or corresponds to the lift amount. When the engine stop time T is in the range of T1 <T <T3, the decompression cam 59A is positioned closer to the second operating position P2 as the engine stop time T becomes longer. When the engine stop time T is in the range of T ≧ T3, the decompression cam 59A is positioned at the second operating position P2.

  In this embodiment, the same operating positions P1 and P2 as in the basic embodiment are used. However, for example, an operating position different from that in the basic embodiment may be used in order to optimize the characteristics in accordance with the characteristics shown in FIG.

  With respect to the routine executed by the ECU 20, only the switching process routine shown in FIG. 9 is modified as shown in FIG. 12, and the start control routine shown in FIG. 10 is the same. As shown in FIG. 12, in the switching process routine of this embodiment, steps S401 to S403 are the same as steps S101 to S103, but steps S404 to S406 are different.

  When it is determined in step S402 that the engine stop time T exceeds the predetermined time Ts, in step S404, the lift correction amount ΔLh corresponding to the engine stop time T is acquired from the map shown in FIG.

  Next, in step S405, the operation position correction amount ΔP of the decompression cam 59A corresponding to the lift correction amount ΔLh is calculated using a map or the like (not shown). The operating position correction amount ΔP of the decompression cam 59A is determined in advance so as to increase as the lift correction amount ΔLh increases.

  Next, in step S406, the operating position of the decompression cam 59A is set to a position approaching the second operating position P2 by the operating position correction amount ΔP from the first operating position P1.

  According to the present embodiment, when the engine stop time T exceeds the predetermined time Ts, the decompression cam 59A and the amount corresponding to the HLA contraction amount that increases as the engine stop time T increases, that is, the necessary minimum amount, The decompression actuator 57 can be operated. Therefore, the amount of operation can be reduced and battery power consumption and the like can be suppressed as compared with the case where the operation is uniformly performed up to the second operation position P2 as in the basic embodiment. Of course, according to this embodiment, it is possible to stably obtain the desired minimum decompression lift amount Ldmin of the exhaust valve 9 regardless of the length of the engine stop time T.

  Although the preferred embodiments of the present invention have been described above, other embodiments of the present invention are possible.

  (1) For example, instead of the rotary decompression cam shaft 59 and decompression actuator 57 described above, a slide cam member and decompression actuator may be used.

  (2) In the other embodiment described above (see FIG. 12), the HLA lift correction amount ΔLh is acquired from the map shown in FIG. 11, and the operation position of the decompression cam 59A corresponding to the acquired lift correction amount ΔLh. The correction amount ΔP was calculated, and the operating position of the decompression cam 59A was set based on the operating position correction amount ΔP and the first operating position P1. However, for example, the map shown in FIG. 11 is modified so that the operation position correction amount ΔP can be calculated directly from the engine stop time T, and the decompression cam 59A is based on the calculated operation position correction amount ΔP and the first operation position P1. An operating position may be set.

  Each of the above-described embodiments, examples, and configurations can be arbitrarily combined as long as no contradiction occurs. The embodiments of the present invention include all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

1 Internal combustion engine
8 Exhaust port 9 Exhaust valve 11 Exhaust camshaft 12 In-cylinder combustion chamber 20 Electronic control unit (ECU)
50 Decompression device 51 Valve spring 52 Rocker arm 53 Hydraulic lash adjuster (HLA)
57 Decompression actuator 59 Decompression camshaft

Claims (1)

A decompression device for communicating the in-cylinder combustion chamber with the exhaust passage in order to release the in-cylinder pressure at least during the compression stroke;
A control unit configured to control the decompression device;
With
The decompression device includes an exhaust valve that opens and closes the exhaust passage, a valve spring that biases the exhaust valve in a closing direction, a rocker arm that receives a driving force from a camshaft and operates the exhaust valve in an opening direction. A hydraulic lash adjuster that forms the rocking center of the rocker arm, a cam member that can selectively lift the hydraulic lash adjuster to the open side of the exhaust valve, and a decompression actuator that drives the cam member.
The control unit operates the decompression actuator to lift the hydraulic lash adjuster so that the exhaust valve is always opened when the internal combustion engine is started.
The control unit is configured such that when the stop time from the stop to restart of the internal combustion engine exceeds a predetermined time, the hydraulic lash adjuster at the time of restart is compared with a case where the stop time does not exceed the predetermined time. A control apparatus for an internal combustion engine, characterized by increasing a lift amount.

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