JP4539538B2 - Energy recovery device - Google Patents

Description

  The present invention relates to an energy recovery device that increases the pressure of a part of an exhaust passage of an engine and recovers the increased pressure as energy.

  In Patent Document 1, an exhaust throttle valve is disposed in an exhaust passage of an engine, and a high-pressure gas tank is installed so as to communicate with a portion of the exhaust passage upstream of the portion where the exhaust throttle valve is disposed. It is disclosed that the pressure of the exhaust gas upstream of the exhaust throttle valve is increased by reducing the opening of the throttle valve, and the increased exhaust gas is accumulated and held in a high-pressure gas tank.

JP 2002-147217 A

  In the device described in Patent Document 1, the pressure on the upstream side of the exhaust throttle valve is increased only by closing the exhaust throttle valve. The pressure upstream of the exhaust throttle valve is efficiently increased in this way, for example, during an acceleration operation, and in an operation state where fuel cut occurs at the time of deceleration, the pressure is efficiently increased. May not be able to increase.

  Accordingly, an object of the present invention is to provide an energy recovery device that can increase the pressure upstream of the exhaust throttle valve more efficiently when the fuel cut occurs at the time of deceleration. To do.

  In order to solve the above-described problem, an energy recovery device according to the present invention closes an exhaust throttle valve provided in an exhaust passage when performing fuel cut during deceleration, and closes an exhaust passage upstream of the exhaust throttle valve. An energy recovery device for increasing pressure and recovering the increased pressure as energy, and when increasing the pressure of the exhaust passage on the upstream side of the exhaust throttle valve, the pressure increase for promoting the pressure increase of the exhaust passage It is provided with a promotion means.

  When the pressure in the exhaust passage on the upstream side of the exhaust throttle valve is increased by the pressure increase promoting means, the pressure increase in the exhaust passage is promoted. Therefore, even when the fuel cut is performed at the time of deceleration, the exhaust is more efficiently performed. It is possible to increase the pressure in the passage.

  The pressure increase promoting means includes a variable valve mechanism that makes variable the valve timing of at least one of the intake and exhaust valves, and changes the valve timing of at least one of the intake and exhaust valves so that the intake air amount increases. preferable. As a result, the amount of intake air increases when energy is recovered, and the amount of fluid reaching the exhaust passage can be increased. Therefore, the pressure increase in the exhaust passage is promoted.

  Further, the pressure increase promoting means includes a variable valve mechanism that makes the lift amount of at least one of the intake and exhaust valves variable, and when the lift amount of at least one of the intake and exhaust valves is changed so that the intake air amount increases. preferable. As a result, the amount of intake air increases when energy is recovered, and the amount of fluid reaching the exhaust passage can be increased. Therefore, the pressure increase in the exhaust passage is promoted.

  Further, it is preferable that the pressure increase promoting means controls the overlap amount to be zero or negative. Thereby, since the overlap amount becomes zero or less, it is prevented that the fluid in the exhaust passage is pushed out to the intake passage side due to the pressure of the fluid in the exhaust passage and flows backward. Therefore, the fluid once reaching the exhaust passage is not excluded from the exhaust passage, and the fluid from the intake passage side is newly added thereto, so that the pressure increase in the exhaust passage is promoted. In addition, by making the overlap amount negative, it becomes possible to form a negative pressure in the cylinder at the initial stage of the intake stroke, and then the air in the intake passage can be urged by the negative pressure. Thereby, it becomes possible to inhale more air in the intake passage into the cylinder.

  Further, it is preferable that the pressure increase promoting means makes the closing timing of the intake valve earlier than the closing timing when energy is not recovered. Thereby, it is possible to reduce the air once reaching the cylinder from being pushed out to the intake passage side.

  In particular, the pressure increase promoting means preferably closes the intake valve near the bottom dead center. As a result, the air once reaching the cylinder is prevented from being pushed out to the intake passage side due to the rise of the piston.

  Furthermore, the pressure increase promoting means may further comprise intake throttle valve opening / closing control means, and the opening of the intake throttle valve may be larger than the opening when energy recovery is not performed. As a result, the opening of the intake throttle valve is increased during energy recovery, so that air can be more reliably taken into the cylinder.

  Alternatively, the pressure increase promoting means includes a variable compression ratio mechanism capable of changing the geometric compression ratio of the engine, and has a higher geometric compression ratio than the geometric compression ratio when energy is not recovered. It is preferable. As a result, air can be sent to the exhaust passage at a higher pressure, and as a result, the pressure increase in the exhaust passage can be promoted.

  An embodiment of an energy recovery device according to the present invention will be described in detail with reference to the drawings.

  First, a first embodiment of the energy recovery device according to the present invention will be described below. The concept of the engine system in the first embodiment is shown in FIG. The engine 10 in the first embodiment is an in-cylinder injection type in which gasoline, which is fuel, is directly injected into the combustion chamber 14 from the fuel injection valve 12 and ignited by the spark plug 16.

  The cylinder head 22 formed with the intake port 18 and the exhaust port 20 respectively facing the combustion chamber 14, and the valve operating mechanism 28 for driving the intake valve 24 and the exhaust valve 26, and the air-fuel mixture in the combustion chamber 14 are ignited. And an igniter 30 for generating a spark in the spark plug 16 is mounted.

  The valve operating mechanism 28 can freely change the phase and lift amount of the operating angle (operating angle) of the intake valve 24 and the exhaust valve 26, that is, can freely change their valve timing, and can freely increase their lift amount. The variable valve mechanism is variable. Although not shown, the valve mechanism 28 moves the intake valve 24 and the exhaust valve 26 by the electromagnetic force of the electromagnetic coil, and the intake and exhaust valves 24 and 26 are electromagnetically driven valves. Therefore, the phase of the working angle and the lift amount can be freely changed by the electromagnetic force by the energization drive controlled by the electromagnetic coils of the intake valve 24 and the exhaust valve 26.

  At the upstream end side of the intake pipe 34 connected to the cylinder head 22 so as to communicate with the intake port 18 and defining the intake passage 32 together with the intake port 18, dust contained in the atmosphere is removed to remove the intake passage 32. An air cleaner 36 is provided for guiding the air. The portion of the intake pipe 34 that is located downstream of the air cleaner 36 and upstream of the surge tank 38 is opened by the throttle actuator 42 based on the depression amount of the accelerator pedal 40 operated by the driver. An intake throttle valve whose degree of adjustment is adjusted, that is, an electronically controlled intake throttle valve (hereinafter referred to as “throttle valve”) 44 is incorporated. However, the depression operation of the accelerator pedal 40 and the opening / closing operation of the throttle valve 44 can be separated and electronically controlled.

  An exhaust throttle valve 50 that allows the exhaust passage 46 to be closed is disposed in the middle of an exhaust pipe 48 that is connected to the cylinder head 22 so as to communicate with the exhaust port 20 and defines the exhaust passage 46 together with the exhaust port 20. ing. The exhaust throttle valve 50 is a poppet valve in which an umbrella-shaped valve body 50a movable in the direction of the flow of exhaust gas moves in a direction perpendicular to the annular valve seat 50b. Therefore, when the valve body 50a is seated on the valve seat 50b, excellent closing performance of the exhaust passage 46 is ensured when the exhaust throttle valve 50 is closed. The valve body 50a of the exhaust throttle valve 50 is actuated by a pneumatic actuator 52, and has a closed position in which the valve seat 50b is seated and an open position in which the valve seat 50b is held at a predetermined interval. A portion of the exhaust passage 46 upstream of the exhaust throttle valve 50 has a control valve 54, and a recovery passage 57 defined by a recovery pipe 56 communicates with the pressure accumulation tank 58 via the recovery passage 57. It is connected. In addition to the collection pipe 56, a discharge pipe 62 having a control valve 60 is connected to the pressure accumulation tank 58 so that the pressure in the pressure accumulation tank 58 can be used.

  The engine 10 includes various sensors that detect various values and output them to an electronic control unit (hereinafter referred to as ECU) 64. Specifically, an intake pressure sensor 66 that detects the pressure of the air in the intake pipe 34, that is, the intake pressure, is provided. Further, an accelerator position sensor 68 that detects a position corresponding to the depression amount of the accelerator pedal 40 operated by the driver is provided. Further, a throttle position sensor 69 for detecting the opening degree of the throttle valve 44 is provided. A crank position sensor 78 for detecting a crank rotation signal of a crank shaft 76 to which the piston 70 is connected via a connecting rod 74 is attached to the cylinder block 72 in which the piston 70 reciprocates. In the first embodiment, the crank position sensor 78 is also used as an engine speed sensor. Furthermore, a pressure sensor 80 is provided for detecting the pressure of the fluid that is exhaust gas or air in the exhaust pipe 48 upstream of the exhaust throttle valve 50. A pressure sensor 82 that detects the pressure in the pressure accumulation tank 58 is also provided. Furthermore, a stop lamp switch 86 that outputs a signal based on depression of the brake pedal 84 is provided. Furthermore, a vehicle speed sensor 88 for detecting the vehicle speed is also provided.

  The ECU 64 is composed of a microcomputer including a CPU, ROM, RAM, A / D converter, input interface, output interface, and the like. The above various sensors are electrically connected to the input interface. Based on the detection signals from these various sensors, the ECU 64 electrically outputs a signal from the output interface so that the engine 10 can be smoothly operated according to a preset program, and the fuel injection valve 12. The operation of the valve mechanism 28, the igniter 30, the throttle actuator 42, the actuator 52, the control valve 54, the control valve 60, and the like is controlled.

  In the engine 10, during normal operation, the intake pressure based on the output value from the intake pressure sensor 66, the engine speed based on the output value from the crank position sensor 78, etc., that is, the operation expressed by the engine load and the engine speed. A fuel injection amount, fuel injection timing, ignition timing, and the like are set based on the state. At that time, the correction is made according to the depression amount of the accelerator pedal 40 based on the output value from the accelerator position sensor 68, and the fuel injection is performed based on the corrected fuel injection amount, fuel injection timing, and ignition timing. The valve 12 and the spark plug 16 are controlled.

  In the engine 10, the engine speed derived using the value detected by the crank position sensor 78 is equal to or higher than a predetermined speed (hereinafter referred to as “fuel cut speed”), and the accelerator position sensor 68 is used. When the detected depression amount of the accelerator pedal 40 is “0”, that is, when the accelerator pedal 40 is not depressed, the fuel injection from the fuel injection valve 12 is stopped (hereinafter referred to as “fuel cut”). Is set to However, when such a fuel cut state continues and the engine speed decreases and reaches another predetermined speed (hereinafter referred to as “fuel cut return speed”), fuel injection is resumed. In addition, when the fuel cut is performed, it corresponds in general at the time of deceleration.

  Further, in the engine 10, the valve mechanism 28 is controlled by the ECU 64 so that when the engine speed is high during normal operation, a predetermined amount of overlap between the intake valve 24 and the exhaust valve 26 occurs. . Thereby, the air is effectively guided into the combustion chamber 14. On the other hand, when the engine speed is low during normal operation, the engine speed is high in order to prevent the exhaust gas from flowing backward from the exhaust passage 46 into the combustion chamber 14 and causing unstable combustion. The valve operating mechanism 28 is controlled so that the amount of overlap is less than that of the case or no overlap occurs. The reason why the intake and exhaust valves 24 and 26 are controlled in this way is that a valve timing (hereinafter referred to as “normal valve timing”) for normal operation stored in advance in the ROM is set. It is.

  In the first embodiment, there is a valve timing (hereinafter referred to as “recovery valve timing”) when energy recovery described later is performed with respect to the normal valve timing. When performing energy recovery, instead of the normal valve timing, the recovery valve timing also stored in the ROM is set, the valve timings of the intake and exhaust valves 24 and 26 are defined, and the valve operating mechanism 28 is controlled. Is called. As will be described later, the recovery valve timing is a valve timing that makes it possible to increase the amount of intake air into the combustion chamber 14, that is, the cylinder. This is a valve timing that is used when energy recovery is performed, that is, when a fuel cut is being performed, so it is not necessary to consider combustion, and it is particularly desirable that the valve timing captures as much air as possible. . In other words, the valve timing increases the actual compression ratio. The actual compression ratio is obtained by multiplying the apparent geometric compression ratio by the volume efficiency, and an increase in the intake air amount corresponds to an increase in the actual compression ratio.

  By the way, in the engine 10, the exhaust gas flowing through the exhaust passage 46 has the exhaust throttle valve 50 fully opened during the normal operation, and is finally released to the atmosphere. On the other hand, in the above state where the fuel is cut when the vehicle is decelerated, energy is extracted by effectively utilizing the fluid flowing through the exhaust passage 46 and is set to be recovered. Yes. The energy recovery will be described in detail below. As will be described later, while fresh air from the fuel cut flows through the exhaust passage 46 (however, some exhaust gas may be mixed), the fluid reaching the exhaust passage 46 is damped to increase the pressure of the fluid. In order to increase the pressure of the fluid in the exhaust passage 46 more efficiently, a pressure increase promoting means is provided. In the first embodiment, the intake valve 24, the valve operating mechanism 28, the throttle actuator 42, the throttle valve 44, the ECU 64, and the like constitute part of the pressure increase promoting means.

  Hereinafter, the energy recovery of the first embodiment including the pressure increase promoting means of the first embodiment will be described in detail based on the control flowchart of FIG. The control flowchart of FIG. 2 is repeated approximately every 20 ms.

  First, in step S201, the ECU 64 determines whether or not the vehicle is decelerating. Specifically, it is determined whether or not the depression amount of the brake pedal 84 is “1” under the deceleration condition, that is, whether or not the stop lamp switch 86 is ON. If it is determined that the vehicle is decelerating, the process proceeds to step S203. If the result in step S201 is negative, the process proceeds to step S217 and subsequent steps, which will be described later.

  In step S203, it is determined whether the fuel is being cut. “Fuel cut in progress” corresponds to the case where the amount of depression of the accelerator pedal is “0” and the engine speed is equal to or higher than the fuel cut speed as described above. Specifically, whether or not the fuel is being cut is determined by whether or not the fuel injection amount is “0”. During normal operation, in order to produce a predetermined output by the engine 10, the fuel injection amount larger than “0” is guided as described above, and fuel injection is performed. Therefore, the result is negative in step S203, and step S217. Proceed to the following, but this will be described later.

  If both affirmative in step S201 and step S203, the process proceeds to step S205, where the predetermined opening, which is defined by searching the normal opening map, here the throttle valve 44 that is fully closed, The collection opening is first set so as to open at a large predetermined opening. The recovery opening degree of the throttle valve 44 is a predetermined opening degree and is a specified value that regulates the throttle valve 44 to a certain opening degree (including the fully open state) between the fully closed state and the fully opened state. Then, an operation signal is output to the throttle actuator 42 so that the recovery opening is obtained. Accordingly, in step S207, the exhaust throttle valve 50 is closed until it is fully closed. Specifically, an operation signal is output to the actuator 52 so that the exhaust throttle valve 50 is closed. Next, in step S209, the recovery valve timing is set. When the recovery valve timing is set, the ECU 64 controls the valve mechanism 28 so as to execute the recovery valve timing for the intake and exhaust valves 24 and 26. The recovery valve timing preferably changes based on the engine speed at that time.

  Here, the collection valve timing of the first embodiment will be described based on the valve timing diagram of FIG. FIG. 3A shows the valve timing when the engine speed is low speed, and FIG. 3B shows the valve timing when the engine speed is high speed. Note that the threshold value of whether the engine rotation is high speed or low speed is, for example, 4000 rpm.

  The valve timing when the engine rotation in FIG. 3 (a) is low-speed rotation is as follows: the exhaust valve 26 opens at 45 ° (45 ° BBDC) before bottom dead center, and closes at 3 ° (3 ° ATDC) after top dead center. The valve timing is such that the intake valve 24 opens at 90 ° (90 ° ATDC) after top dead center and closes at 30 ° (30 ° ABDC) after bottom dead center. In other words, the intake valve 24 is opened after a certain period of time has elapsed since the exhaust valve 26 is closed so that the opening timing of the intake valve 24 is later than the opening timing of the normal valve timing when energy is not recovered. Is opened, so that there is no overlap between the so-called intake and exhaust valves 24, 26, and a "negative" overlap occurs. Therefore, in the initial stage of the intake stroke, the piston 70 descends with both the exhaust valve 26 and the intake valve 24 closed, so the negative pressure in the cylinder rises. Thereafter, in the latter stage of the intake stroke, the intake valve 24 is opened, so that air is vigorously brought into the cylinder under the influence of the negative pressure. On the other hand, a vibration wave accompanying the negative pressure is generated in the air in the intake passage 32. That is, intake pulsation occurs. Then, the vibration wave is reflected at the open end of the atmosphere, and the closing timing of the intake valve 24 is set so that the intake valve 24 is closed at the timing when the vibration wave that is a sine wave reaches the inside of the cylinder. Is set. Therefore, supercharging can be realized by a so-called inertia effect. In this way, more air can be taken into the cylinder. Therefore, more fluid can be sent to the exhaust passage 46. Note that the opening timing and the closing timing of the slow opening of the intake valve 24 shown in FIG. 3 synchronize the closing timing of the intake valve 24 and the arrival timing of the sine wave of the intake pulsation as described above. Since it is set for the purpose of illustration, it is desirable to set a unique timing according to the intake pipe length, cylinder volume, cylinder shape, and the like.

  On the other hand, the valve timing when the engine rotation of FIG. 3B is high-speed is as follows: the exhaust valve 26 opens at 45 ° (45 ° BBDC) before the bottom dead center and 3 ° (3 ° ATDC) after the top dead center. The valve timing is closed and the intake valve 24 opens at 10 ° before top dead center (10 ° BTDC) and closes at 40 ° after bottom dead center (40 ° ABDC). That is, it is defined so that a positive overlap occurs. As a result, the air in the intake passage 32 is pulled by the fluid to be discharged, so that the fluid in the cylinder is quickly replaced, and air is sucked into the cylinder at a faster flow rate. And can be sent to the exhaust passage 46.

  As described above, when it is determined that the fuel is being cut at the time of deceleration, the throttle valve 44 is controlled to increase its opening, the exhaust throttle valve 50 is closed, and the recovery valve timing is set. Thus, the valve mechanism 28 is controlled, so that sufficient air from the intake passage 32 flows into the combustion chamber 14, and the air that flows in is directly pushed into the exhaust passage 46 by the vertical movement of the piston 70, and the exhaust throttle valve 50. As a result, the pressure in the exhaust passage 46 on the upstream side of the exhaust throttle valve 50 increases. Particularly in the first embodiment, when the pressure in the exhaust passage 46 is increased, the recovery valve timing is set as described above, and the intake and exhaust valves 24 and 26 are operated. Inhaled. Therefore, more air is caused to flow through the exhaust passage 46 and the pressure increase in the exhaust passage 46 is promoted. As a result, since the time during which fuel is cut is short, even when the time available for energy recovery is short, the pressure in the exhaust passage 46 upstream of the exhaust throttle valve 50 can be sufficiently increased in a short time. It becomes possible to increase. However, since the fuel injection amount is “0”, the fluid reaching the exhaust passage 46 may be exhaust gas when the exhaust throttle valve 50 is initially closed, but is generally air, that is, fresh air. It is desirable that this is only fresh air.

  Here, as the pressure in the exhaust passage 46 increases, the pressure in the exhaust passage 46 upstream of the exhaust throttle valve 50 increases and exceeds the pressure in the pressure accumulating tank 58, and the pressure as energy Can be recovered. Therefore, in order to determine whether or not this pressure can be recovered, in step S211, the pressure in the exhaust passage 46 upstream from the exhaust throttle valve 50 is the pressure in the pressure accumulation tank 58 ("tank internal pressure" in FIG. 2). It is determined whether or not it is above. Then, when the exhaust throttle valve 50 is initially closed, the pressure in that portion of the exhaust passage 46 may be lower than the pressure in the pressure accumulation tank 58. In this case, the result is negative, and the process proceeds to step S213, where the control valve 54 Is left closed. On the other hand, when the pressure in that portion of the exhaust passage 46 reaches a pressure equal to or higher than the pressure in the pressure accumulation tank 58, the result in step S211 is affirmative, the process proceeds to step S215, and the control valve 54 is opened. As a result, the increased pressure in the exhaust passage 46 upstream of the exhaust throttle valve 50 causes the fluid in that portion of the exhaust passage 46 to flow into the pressure accumulation tank 58 via the recovery passage 57, and the exhaust passage As the pressure of 46 increases, the pressure in the pressure accumulating tank 58 increases. That is, as a result, the pressure in the pressure accumulation tank 58 increases, and the pressure as energy is recovered in the pressure accumulation tank 58.

  In the first embodiment, this is basically continued until the result is negative in step S201 or step S203.

  If it is denied in step S201 that the vehicle is not decelerating or that the fuel is not being cut in step S203, the process proceeds to step S217 as described above, and for normal operation when energy recovery is not performed. Control or control for terminating energy recovery is performed. First, the control valve 54 is closed in step S217, the normal valve timing is set in step S219, and the intake / exhaust valves 24 and 26 are operated based on this. In step S221, the exhaust throttle valve 50 is opened. That is, an operation signal is output to the actuator 52 so that the exhaust throttle valve 50 is opened. Further, in step S223, a normal opening degree map is set for adjusting the opening degree of the throttle valve 44. Accordingly, the opening degree of the throttle valve 44 is defined by searching the normal opening degree map based on the depression amount of the accelerator pedal 40 and the engine speed, and an operation signal is output to the throttle actuator 42 so as to be the opening degree. Will be.

  In the first embodiment, as described above, when recovering energy, the recovery valve timing is set, and more air is sucked into the cylinder. This is done together with closing the exhaust throttle valve 50 and opening the throttle valve 44 to the recovery opening, so that even when performing a deceleration operation with a fuel cut to perform energy recovery, The pressure in the exhaust passage 46 on the upstream side of the exhaust throttle valve 50 can be quickly increased to efficiently recover energy.

  As mentioned above, although this invention has been demonstrated based on said 1st embodiment, this invention is not limited to this. For example, in the control flowchart, the order of steps S205, S207, and S209 may be interchanged. Further, the order of steps S217, S219, S221, and S223 may be interchanged. Further, another step is provided before step S201, and in this step, the pressure in the pressure accumulating tank 58 is a pressure allowed for the pressure accumulating tank 58 and is predetermined and stored in the ROM. The upper limit value may be compared. Thereby, when the pressure in the pressure accumulating tank 58 is sufficient, it is possible to reliably prevent further energy recovery. And when it is judged that the pressure in the pressure accumulation tank 58 is below an upper limit, it is preferable to progress to said step S201.

  In the first embodiment, the present invention is applied to the in-cylinder injection type engine. However, the present invention is not limited to this, and can be applied to various engines such as a port injection type engine and a diesel engine. . The fuel used is not limited to gasoline, but may be alcohol fuel, liquefied natural gas, or the like. In the first embodiment, the throttle valve 44 is used as the intake throttle valve. For example, the intake throttle valve is provided in parallel with the throttle valve 44, branches from the intake passage 32 so as to bypass it, and an idle speed control valve (ISCV) for idle control that opens and closes the joining passage. Can be the ISCV. Note that these intake throttle valves do not have to be provided.

  Further, the exhaust throttle valve 50 is not limited to the poppet type valve, and may be any valve such as a butterfly type valve, a shutter type valve, or a valve that opens and closes by rotating a valve body with respect to an axis. . The actuator 52 that operates the exhaust throttle valve 50 is not limited to a pneumatic actuator, and may be a hydraulic or electronically controlled actuator.

  Furthermore, the control valve 54 may be a check valve that automatically opens when the pressure in the exhaust passage 46 becomes equal to or higher than a specified pressure.

  Furthermore, in the first embodiment, one pressure accumulating tank 58 is provided, but a plurality of pressure accumulating tanks 58 may be provided. Furthermore, a plurality of pressure accumulating tanks may be divided and arranged in the engine room, the vehicle body floor, or the like. In addition, since not only fresh air but also a part of exhaust gas may flow into the pressure accumulating tank 58, the pressure accumulating tank 58 is made of a material having excellent corrosion resistance like the exhaust pipe 48. And good. Similarly, the recovery pipe 56 and the discharge pipe 62 are preferably made of a material having excellent corrosion resistance.

  Further, although the valve operating mechanism 28 using the intake valve 24 and the exhaust valve 26 as electromagnetically driven valves is used, other valve operating mechanisms such as intake / exhaust valves 24 and 26 having cams and camshafts are used. It is not excluded. In order to change the valve timing and the overlap amount, any mechanism that makes the phase of the working angle of at least one of the intake valve 24 and the exhaust valve 26 variable may be used. Such devices include a variable valve timing mechanism and a variable valve timing-lift mechanism. It is preferable that the phase of the operating angle of the intake valve 24 or the exhaust valve 26 is made variable by the hydraulic pressure controlled by the ECU 64 or the like. For example, some cams have a plurality of cams, and by switching the cams, the phase of the operating angle of the intake valve 24 or the exhaust valve 26 is continuously changed. In addition, by providing a variable timing controller on the camshaft that is rotated by the timing chain and adjusting the hydraulic pressure of the advance chamber in the housing, the phase of the operating angle of the intake valve 24 and the exhaust valve 26 can be adjusted. There are things that change continuously.

  In addition, when the fuel is cut, a dedicated valve timing is set when the fuel is being cut so that the engine brake effect can be effectively applied to the engine 10, but energy recovery is impossible or unnecessary. It is also good to do.

  The pressure as energy collected in the pressure accumulating tank 58 is used when the control valve 60 is opened by an operation signal from the ECU 64. Although the application is not illustrated, for example, there is an initial drive of a turbocharger. The turbo lag is improved by injecting the compressed air in the pressure accumulating tank 58 before the turbine.

  By the way, in the first embodiment, the recovery valve timing is set at the time of energy recovery, and the intake valve 24 is opened slowly so that the inertial supercharging effect can be maximized when the engine speed is low. The intake air amount was increased by realizing a certain amount of overlap when it was rotating at high speed. However, the present invention is not limited to such a recovery valve timing. Hereinafter, an example of other recovery valve timing and the like will be described with reference to the drawings.

  FIG. 4 shows an example of the recovery valve timing when the valve overlap is zero. In the first embodiment, the intake air amount is increased by using the overlap when the engine speed is high speed. However, if the pressure in the exhaust passage 46 becomes higher than a certain level, the intake air due to the overlap is increased. The volume increase may not be effective. For example, when the pressure of the exhaust passage 46 is high to such a level and the intake and exhaust valves 24 and 26 are both opened, that is, when an overlap occurs, the exhaust passage 46 has a high pressure from the exhaust passage 46 side. The fluid is pushed back into the cylinder, resulting in a backflow, which may result in a decrease in pressure in the exhaust passage 46. Therefore, in this case, as shown in FIG. 4A, the valve opening timing of the intake valve is delayed so that no valve overlap occurs, thereby preventing the back flow of the fluid once reaching the exhaust passage 46. It is effective to do. Even when the engine is rotating at a low speed, it is effective to prevent the overlap from occurring as described above. In the energy recovery, the exhaust passage can be obtained by setting the overlap to zero or negative. The backflow of fluid from 46 to the intake passage 32 side is prevented. As a result, the pressure increase in the exhaust passage 46 is promoted, and the pressure upstream of the exhaust throttle valve 50 can be increased more efficiently and quickly. In order to realize the recovery valve timing shown in FIG. 4A, it is preferable to delay the entire opening period of the intake valve 24 at the time of recovery from the normal time, as schematically shown in FIG. 4B. .

  In the first embodiment, the intake air amount is increased by the inertia supercharging effect by, for example, delaying the opening timing of the intake valve 24. However, if the inertia supercharging effect is not taken into account, the amount of intake air can be increased only once the air that has reached the cylinder is trapped in the cylinder. Therefore, it is desirable that the intake valve 24 be closed at a more effective timing. For this purpose, it is effective to advance the closing timing of the intake valve 24 at the time of energy recovery, and the intake valve 24 is preferably closed near the bottom dead center. Specifically, it is preferable that the intake valve 24 is closed before the piston 70 moves up, in other words, before the compression stroke is reached. As a result, the piston 70 can prevent the air in the cylinder from being pushed into the intake passage 32 from inside the cylinder. In order to realize such a recovery valve timing, it is preferable to control the movement of the intake and exhaust valves 24 and 26 as schematically shown in FIG. In FIG. 5, a thin line represents an example of the normal valve timing of the intake / exhaust valves 24 and 26, and a thick line represents an example of the recovery valve timing different from the normal valve timing of the intake valve 24. 5A and 5B, the locus of the lift amount associated with the opening of the intake valve 24 has a substantially trapezoidal shape, and represents that only the closing timing of the intake valve 24 is advanced during energy recovery. 5A is an example effective when both the intake and exhaust valves 24 and 26 are electromagnetically driven valves as in the first embodiment, and FIG. 5B shows at least the intake valve 24. Similarly, it is an effective example in the case of an electromagnetically driven valve. As shown in FIGS. 5A and 5B, it is possible to prevent an increase in the overlap amount of the intake and exhaust valves 24 and 26 by advancing only the closing timing of the intake valve 24. As described above, it is more preferable that no overlap occurs.

  Incidentally, advancing the closing timing of the intake valve 24 can be realized by changing the lift amount in addition to the timing shown in FIG. FIG. 6 schematically shows an example of a recovery valve timing that advances the closing timing of the intake valve 24 by reducing the lift amount of the intake valve 24. In FIG. 6, the thin line represents an example of the normal valve timing of the intake / exhaust valves 24 and 26, and the thick line represents an example of the recovery valve timing different from the normal valve timing of the intake valve 24. FIG. 6A shows that the intake valve 24 is opened slowly and quickly by reducing the lift amount of the intake valve 24. By setting the recovery valve timing to reduce the lift of the intake valve 24 in this way, the intake valve 24 is also opened slowly, and the valve overlap can be reduced. FIGS. 6B and 6C schematically show an example of valve timing in which not only the lift amount of the intake valve 24 is reduced but also the opening period of the intake valve is advanced. The recovery valve timings shown in FIGS. 6A to 6C are effective when at least the intake valve 24 is an electromagnetically driven valve as in the first embodiment, and are shown in FIG. 6B. The recovery valve timing is effective when both the intake and exhaust valves 24 and 26 are electromagnetically driven valves. Even if the lift amount is reduced so that the intake valve 24 is quickly closed as described above, a sufficient intake air amount can be realized mainly during low load operation. Therefore, it is possible to promote an increase in pressure in the exhaust passage 46 on the upstream side of the exhaust throttle valve 50.

  FIG. 7 schematically shows a recovery valve timing for increasing the intake air amount by increasing both the lift amounts of the intake valve 24 and the exhaust valve 26. In FIG. 7, the valve timing represented by a thin line is a normal valve timing, and the bold valve represents a recovery valve timing different from the normal valve timing. At this valve timing, both the lift amount of the intake valve 24 and the exhaust valve 26 are increased, the valve opening period of the exhaust valve 26 is advanced, and the valve opening period of the intake valve 24 is delayed. Will not change and will not grow. By doing so, it is possible to promote an increase in pressure in the exhaust passage 46 upstream of the exhaust throttle valve 50. As described above, it is preferable that no overlap occurs. However, since the recovery valve timing shown in FIG. 7 varies both the lift amount and the valve timing, it is effective when both the intake and exhaust valves 24 and 26 are electromagnetically driven valves.

  Next, a second embodiment of the present invention will be described. In the second embodiment of the present invention, unlike the first embodiment and the modification of the recovery valve timing thereof, the pressure increase in the intake passage 46 is promoted by replacing the geometric compression ratio of the engine itself. Yes. That is, in the second embodiment, a variable compression ratio mechanism capable of changing the geometric compression ratio of the engine is provided as the pressure increase promoting means, and the energy is higher than the geometric compression ratio when energy is not recovered. The geometric compression ratio is increased when recovery is performed. This will be described below with reference to FIGS. 8 to 10, but the same components as those of the engine system of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 8 is a conceptual diagram of the engine system of the second embodiment. FIG. 9 is an engine (hereinafter referred to as a variable compression ratio engine) in which the compression ratio (geometric compression ratio) can be changed in the engine system of FIG. 10) is a diagram showing a configuration of the mechanism 110, and FIG. 10 is a diagram schematically showing a transition in which the compression ratio is changed. The variable compression ratio engine 110 changes the compression ratio by moving a cylinder block 112 having cylinders in the axial direction of the cylinder with respect to a crankcase 114 to which a piston 70 is connected. The mechanism for changing the compression ratio of the variable compression ratio engine 110 is disclosed in Japanese Patent Application Laid-Open No. 2005-69179 filed by the present applicant, and an outline of the variable compression ratio engine 110 will be described. , Formed in a fitting portion between a part of the cylinder block and a part of the crankcase, and by providing a gap along the axial direction of the cylinder between the cylinder block and the crankcase in the fitting portion, A guide portion for guiding the relative movement between the cylinder block and the crankcase in the axial direction, and the cylinder block and the crankcase are moved relative to each other according to the guide portion to change the compression ratio of the engine (internal combustion engine). And an compression ratio control means.

  As shown in FIG. 9, a plurality of raised portions 116 are formed at the lower portions on both sides of the cylinder block 112, and a cam housing hole 118 is formed in each raised portion 116. The cam housing hole 118 has a circular shape and is formed so as to be perpendicular to the cylinder axial direction and parallel to the arrangement direction of the plurality of cylinders. The plurality of cam housing holes 118 on one side are all located on the same axis. The pair of axes of the cam storage holes 118 on both sides of the cylinder block 112 are parallel.

  In the crankcase 114, a standing wall 120 is formed so as to be positioned between the plurality of raised portions 116 in which the cam housing holes 118 are formed. A semicircular recess is formed on the surface of each standing wall 120 facing the outside of the crankcase 114. Each standing wall 120 is provided with a cap 124 attached by a bolt 122, and the cap 124 also has a semicircular recess. Further, when the cap 124 is attached to each standing wall portion 120, a circular bearing housing hole 126 is formed. The shape of the bearing storage hole 126 is the same as that of the cam storage hole 118 described above.

  Similar to the cam housing hole 118, the plurality of bearing housing holes 126 are perpendicular to the axial direction of the cylinder and parallel to the arrangement direction of the plurality of cylinders when the cylinder block 112 is attached to the crankcase 114. Are formed respectively. The plurality of bearing housing holes 126 are also formed on both sides of the cylinder block 112, and the plurality of bearing housing holes 126 on one side are all located on the same axis. The pair of axes of the bearing housing holes 126 on both sides of the cylinder block 112 are parallel. Further, the distance between the cam housing holes 118 on both sides and the distance between the bearing housing holes 126 on both sides are the same.

  The control shaft 128 is inserted through the two rows of the cam storage holes 118 and the bearing storage holes 126 arranged alternately. As shown in FIG. 9, the control shaft 128 includes a shaft portion 128a and a cam portion 128b having a right circular cam profile fixed to the shaft portion 128a while being eccentric with respect to the central axis of the shaft portion 128a. The movable bearing portions 128c having the same outer shape as the cam portion 128b and rotatably attached to the shaft portion 128a are alternately arranged. The movable bearing portion 128c is provided with a shaft housing hole 128e, and the movable bearing portion 128c rotates with respect to the shaft portion 128a by adopting a configuration in which the shaft portion 128a of the control shaft 128 is inserted. It is possible to move. The pair of control shafts 128 have a mirror image relationship. Further, a mounting portion 128d of a worm wheel 130 described later is formed at the end of the control shaft 128. The center axis of the shaft portion 128a and the center of the attachment portion 128d are eccentric, and the center of the cam portion 128b and the center of the attachment portion 128d coincide.

  The movable bearing portion 128c is also eccentric with respect to the shaft portion 128a, and the amount of eccentricity is the same as that of the cam portion 128b. In each control shaft 128, the eccentric directions of the plurality of cam portions 128b are the same. In addition, since the outer shape of the movable bearing portion 128c is the same circle as the cam portion 128b, the outer surface of the plurality of cam portions 128b and the outer surface of the plurality of movable bearing portions 128c are rotated by rotating the movable bearing portion 128c. Can be matched.

  A worm wheel 130 is attached to one end of the shaft portion 128 a of each control shaft 128. Worm gears 132a and 132b are engaged with the pair of worm wheels 130 fixed to the ends of the pair of control shafts 128, respectively. The worm gears 132 a and 132 b are attached to one output shaft of the motor 134. The worm gears 132a and 132b have spiral grooves that rotate in opposite directions. For this reason, when the motor 134 is rotated, the pair of control shafts 128 rotate in the reverse direction via the worm wheel 130. The motor 134 is fixed to the cylinder block 112 and moves integrally with the cylinder block 112.

  Next, a method for controlling the compression ratio in the variable compression ratio engine 110 having the above-described configuration will be described with reference to FIG. FIG. 10A to FIG. 10C are cross-sectional views showing the relationship between the cylinder block 112, the crankcase 114, and the control shaft 128 constructed between them. 10A to 10C, the central axis of the shaft portion 128a is indicated as a, the center of the cam portion 128b is indicated as b, and the center of the movable bearing portion 128c is indicated as c. FIG. 10A shows a state in which the outer peripheries of all the cam portions 128b and the movable bearing portion 128c coincide with each other when viewed from the extension line of the shaft portion 128a. At this time, the pair of shaft portions 128 a are located outside the cam housing hole 118 and the bearing housing hole 126 here.

  When the motor 134 is driven from the state of FIG. 10A to rotate the shaft portion 128a in the direction of the arrow, the state of FIG. 10B is obtained. At this time, since the cam portion 128b and the movable bearing portion 128c are displaced from each other in the eccentric direction with respect to the shaft portion 128a, the cylinder block 112 can be slid toward the top dead center side with respect to the crankcase 114. The sliding amount is maximized when the control shaft 128 is rotated until the state shown in FIG. 10C is reached, and is twice the eccentric amount of the cam portion 128b or the movable bearing portion 128c. The cam portion 129b and the movable bearing portion 128c rotate inside the cam housing hole 118 and the bearing housing hole 126, respectively, and allow the position of the shaft portion 128a to move inside the cam housing hole 118 and the bearing housing hole 126, respectively. is doing.

  By using the mechanism as described above, the cylinder block 112 can be moved relative to the crankcase 114 in the axial direction of the cylinder. As a result, the volume of the combustion chamber 14 of the variable compression ratio engine 110 is changed. Thus, the compression ratio can be variably controlled.

  Referring to FIG. 8, a variable compression ratio engine 110 includes a piston 70 that is connected to a crankshaft 76 and reciprocates in a cylinder. In FIG. 8, for simplicity of description, the control shaft 128 and the worm wheel 130 shown in FIG. 9 are described only on one side where the worm gear 132a is provided, and the control shaft 128 on the remaining worm gear 132b side, etc. The description is omitted.

  In the variable compression ratio engine 110 according to the second embodiment, the compression ratio is changed by the relative movement of the cylinder block 112 with respect to the crankcase 114 in the axial direction of the cylinder by driving the motor 134. Here, the cylinder block side guide portion 112a which is one end of the cylinder block 112 on the crankcase 114 side and the crankcase side guide portion 114a which is one end of the crankcase 114 on the cylinder block side are in a gap fitting state. . Therefore, the relative movement of the cylinder block 112 with respect to the crankcase 114 is restrained by the cylinder block side guide portion 112a and the crankcase side guide portion 114a, and as a result, the direction of relative movement is the axial direction of the cylinder.

  The control for energy recovery in the second embodiment in the engine system including the variable compression ratio engine having such a configuration is substantially the same as the control in the first embodiment. Therefore, only differences are noted, and explanations regarding other controls are omitted. In the second embodiment, the recovery valve timing is set (step S209) in the control flowchart (see FIG. 2) of the first embodiment, and then the normal valve timing is set (step S219). Instead of setting and executing timing, the geometric compression ratio of the variable compression ratio engine 110 is changed to be high. As a result, during energy recovery, the fluid delivery pressure to the exhaust passage 46 increases, and the pressure increase in the exhaust passage 46 upstream of the exhaust throttle valve 50 can be promoted.

  As in the second embodiment, when recovering energy, the geometric compression ratio may be changed to be high from the beginning to the end. For example, at the beginning of energy recovery, more fluid is discharged from the exhaust passage 46. The volume of the combustion chamber 14 may be increased as shown in FIG. On the other hand, when the pressure in the exhaust passage 46 upstream of the exhaust throttle valve 50 is increased to some extent, more force is required to push the fluid from the cylinder to the exhaust passage 46. When this is the case, it is preferable to change the geometric compression ratio to be high as shown in FIG. 10A and to force the fluid to flow into the exhaust passage 46 with a high compression force. When the geometric compression ratio is switched and controlled in this way, the geometric compression ratio is set as shown in FIG. 10 (b) during normal operation when energy recovery is not performed. It is desirable to change the geometric compression ratio according to the occasional requirement in either of FIGS. 10 (a) and 10 (c).

  In the variable compression ratio engine 110, the cylinder block 112 and the crankcase 114 are moved relative to each other in accordance with guide portions 112a and 114a that guide the relative movement between the cylinder block 112 and the crankcase 114 in the axial direction thereof. The compression ratio of the cylinder block 112 is changed. However, if the gap is large, vibration may occur in the cylinder block 112, which is not preferable. Therefore, in the second embodiment, in order to fix the cylinder block 112 more stably, while ensuring that the relative movement between the cylinder block 112 and the crankcase 114 is performed smoothly, the compression ratio control including the ECU 64 is performed. Based on the operation of changing the compression ratio of the engine by the means, the gap distance between the cylinder block 112 and the crankcase 114 in the guide portions 112a and 114a or the action between the cylinder block 112 and the crankcase 114 in the guide portions 112a and 114a Stabilization means for controlling the force is provided.

  Specifically, as a stabilizing means of the second embodiment, a gap between the cylinder block side guide portion 112a and the crankcase side guide portion 114a in the gap fitting state (hereinafter referred to as “guide portion gap”). ) Is provided with a piezoelectric deformation member 136 that is formed of a piezoelectric element and whose shape changes depending on a voltage applied to the piezoelectric element. When the voltage is applied from the battery 138, the shape of the piezoelectric deformation member 136 changes so that the shape thereof contracts in the radial direction of the cylinder in the guide portion gap.

  Therefore, when no voltage is applied from the battery 138, the piezoelectric deformation member 136 contacts both sides of the crankcase side guide portion 114a and the cylinder block side guide portion 112a, and as a result, pushes against both guide portions 112a and 114a. Pressure is applied, and the cylinder block 112 is fixed to the crankcase 114. On the other hand, when a voltage is applied from the battery 138, the piezoelectric deformation member 136 contracts and contacts only with the crankcase side guide portion 114a, and the cylinder block 112 can freely move in the axial direction of the cylinder with respect to the crankcase 114. Relative movement is possible.

  The stabilizing means is not limited to the stabilizing means as described above. For example, in the above-described variable compression ratio engine 110, the gap distance between the cylinder block 112 and the crankcase 114 fixed to the crankcase 114 and the guide portions 112a and 114a or a part of the cylinder block 112 of the guide portions 112a and 114a. A hydraulic cylinder that controls the pressing force acting on the cylinder, or fixed to the cylinder block 112, and a gap distance between the cylinder block 112 and the crankcase 114 in the guide portions 112a and 114a or a part of the crankcase 114 of the guide portions 112a and 114a. You may make it provide the hydraulic cylinder which controls the pressing force which acts on it. The stabilizing means controls the hydraulic pressure of the lubricating oil supplied to the hydraulic cylinder based on the operation of changing the compression ratio of the engine 110 by the compression ratio control means, so that the cylinder block 112 and the crank in the guide portions 112a and 114a It is desirable to control the gap distance with the case 114 or the acting force between the cylinder block 112 and the crankcase 114 in the guide portions 112a and 114a. The supply of the lubricating oil to the hydraulic cylinder may be performed by a pump that is connected to the crankshaft 76 and pumps the lubricating oil stored in the oil pan using the output of the engine as a power source.

  Alternatively, in the variable compression ratio engine, an elastically deformable member may be provided in the gap between the cylinder block 112 and the crankcase 114 in the guide portions 112a and 114a. Thereby, when the cylinder block 112 and the crankcase 114 move relative to each other, the elastically deformable member provided in the gap between the cylinder block 112 and the crankcase 114 in the guide portions 112a and 114a, The cylinder block 112 and the crankcase 114 are crushed and compressed and deformed. As a result, a pressing force is generated on the cylinder block 112 and the crankcase 114 by the elastic energy of the elastically deforming elastic deformation member, and the coupling force between the cylinder block 112 and the crankcase 114 increases.

  As mentioned above, although this invention was demonstrated based on said 1st and 2nd embodiment, this invention is not limited to these. For example, the present invention can change the geometric compression ratio as shown in the second embodiment and its modification while changing the valve timing and the lift amount as shown in the first embodiment and its modification. Is included.

  As described above, when the pressure of the exhaust passage 46 is increased during energy recovery, the pressure in the pressure accumulation tank 58 can be increased correspondingly. Therefore, the use of such stored energy is expanded.

  When the pressure in the exhaust passage 46 increases as described above, a larger force is required to flow the fluid from the cylinder to the exhaust passage, so that the so-called exhaust brake is more effective. Therefore, it is possible to reduce the frequency of use of the brake and the load applied to the brake.

It is a conceptual diagram of the engine system in a first embodiment. It is a control flowchart of a first embodiment. It is a figure showing an example of the collection | recovery valve | bulb timing of 1st embodiment. It is a figure showing other examples of recovery valve timing. It is a figure showing other examples of recovery valve timing. It is a figure showing other examples of recovery valve timing. It is a figure showing other examples of recovery valve timing. It is a conceptual diagram of the engine system of 2nd embodiment. It is a figure which shows the structure of the mechanism of the engine which can change a geometric compression ratio in the engine system of FIG. It is a figure which shows roughly the transition by which a compression ratio is changed with the engine of 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 12 Fuel injection valve 14 Combustion chamber 16 Spark plug 18 Intake port 20 Exhaust port 22 Cylinder head 24 Intake valve 26 Exhaust valve 28 Valve mechanism 30 Igniter 32 Intake passage 34 Intake pipe 36 Air cleaner 38 Surge tank 40 Accelerator pedal 42 Throttle actuator 44 Throttle valve 46 Exhaust passage 48 Exhaust pipe 50 Exhaust throttle valve 50a Valve body 50b Valve seat 52 Actuator 54 Check valve 56 Recovery pipe 58 Accumulation tank 60 Control valve 62 Release pipe 64 ECU
66 Intake pressure sensor 68 Accelerator position sensor 69 Throttle position sensor 70 Piston 72 Cylinder block 74 Connecting rod 76 Crankshaft 78 Crank position sensor 80 Pressure sensor 82 Pressure sensor 84 Brake pedal 86 Stop lamp switch 88 Vehicle speed sensor 110 Compression ratio variable engine 112 Cylinder Block 112
114 Crankcase 116 Raised portion 118 Cam housing hole 120 Standing wall portion 122 Bolt 124 Cap 126 Bearing housing hole 128 Control shaft 128a Shaft portion 128b Cam portion 128c Movable bearing portion 128d Mounting portion 130 Worm wheel 132a, 132b Worm gear 134 Motor 136 Piezoelectric deformation member 138 battery

Claims (6)

Energy recovery that closes the exhaust throttle valve provided in the exhaust passage, raises the pressure in the exhaust passage upstream of the exhaust throttle valve, and recovers the increased pressure as energy when fuel cut is performed during deceleration A device,
When increasing the pressure of the exhaust passage on the upstream side of the exhaust throttle valve, a pressure increase promoting means for promoting a pressure increase of the exhaust passage is provided,
The pressure increase promotion means includes a variable valve mechanism for varying at least one of the valve timing of the intake and exhaust valves, changing at least one of the valve timing of the intake exhaust valve so much intake air amount, the overlap An energy recovery device characterized in that the amount is controlled to be zero or negative .   The pressure increase promoting means includes a variable valve mechanism that makes the lift amount of at least one of the intake and exhaust valves variable, and changes the lift amount of at least one of the intake and exhaust valves so that the intake air amount increases. The energy recovery device according to claim 1. The energy recovery device according to claim 1 or 2 , wherein the pressure increase promoting means makes the closing timing of the intake valve earlier than the closing timing when energy is not recovered. 4. The energy recovery apparatus according to claim 3 , wherein the pressure increase promoting means closes the intake valve near a bottom dead center. The pressure increase promotion means further includes an intake throttle valve opening control means, the opening degree of the intake throttle valve, from claim 1, characterized in that larger than the opening degree of when not subjected to energy recovery of 4 The energy recovery device according to any one of the above. The pressure increase promoting means includes a variable compression ratio mechanism capable of changing the geometric compression ratio of the engine, and makes the geometric compression ratio higher than the geometric compression ratio when energy is not recovered. The energy recovery device according to any one of claims 1 to 5 .

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