JP4165194B2 - Engine compression ratio changing method and variable compression ratio engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable compression ratio engine that changes the compression ratio of an engine.
[0002]
[Prior art]
In the variable compression ratio engine, various advantages can be obtained by changing the compression ratio according to the operating conditions. For example, by reducing the compression ratio at a high load at which knocking is likely to occur, the self-ignition of the fuel can be suppressed, whereby the occurrence of knocking can also be suppressed. When the compression ratio is increased at low loads, the temperature of the air-fuel mixture increases and the combustibility of the fuel increases. For this reason, during acceleration traveling, etc., where load fluctuations are likely to occur, the compression ratio is changed from a high compression ratio to a low compression ratio according to load fluctuations (fluctuations from low loads to high loads). Yes. By performing compression ratio control according to such load fluctuations, fuel efficiency and drivability are improved.
[0003]
In such a conventional variable compression ratio engine, the driving force of the driving source for changing the compression ratio is transmitted to the compression ratio changing mechanism by the worm and the worm wheel meshing with the worm (for example, patent) Reference 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 7-26981
In general, when using a worm and worm wheel for such power transmission, the worm is connected to a drive source such as a motor, the worm wheel is connected to a drive target device (compression ratio changing mechanism), and the gear ratio of both is increased. Yes. In this way, high rotation of the motor can be decelerated by the worm and worm wheel and transmitted to the compression ratio changing device, and the actual compression ratio can be smoothly changed to the target compression ratio. In addition, the worm and worm wheel are known to have a reverse rotation prevention function that makes it difficult to transmit rotation from the worm wheel side to the worm side due to the characteristics of the gear configuration. It works effectively because of its large size. If the variable compression ratio engine is described, after the change to the target compression ratio, unless the rotation is transmitted from the motor side, the compression ratio is maintained at the target compression ratio by this anti-reverse action.
[0006]
[Problems to be solved by the invention]
However, in the conventional variable compression ratio engine, the following problems have been pointed out due to the use of the worm and the worm wheel for power transmission as described above.
For example, if some trouble occurs in the equipment involved in changing the compression ratio when the vehicle is in low load operation, specifically, the compression ratio changing mechanism or its control device, the compression ratio is reduced by The high compression ratio in accordance with the operation is maintained. If the accelerator operation is performed in this state and the driving state of the vehicle shifts to a high-load operation, the occurrence frequency of knocking increases and drivability is impaired. Alternatively, it is necessary to perform engine control ignoring the accelerator operation so that the vehicle cannot be operated in a high load state, and this makes the driver who operates the accelerator feel uncomfortable.
[0007]
The present invention has been made to solve the above-described problems, and an object thereof is to avoid a situation in which the compression ratio of the engine is inadvertently fixed at a high compression ratio.
[0008]
[Means for solving the problems and their functions and effects]
In order to solve at least a part of the problem, in the compression ratio changing method and the variable compression ratio engine of the present invention, when the compression ratio is changed, the driving force of the driving source for changing the compression ratio is changed to the driving source side. And the worm wheel meshing with the worm are transmitted to the compression ratio changing mechanism. As a result, in the compression ratio changing mechanism, the driving device that it has is driven against the combustion chamber combustion pressure to change the compression ratio between the high compression ratio and the low compression ratio.
[0009]
Upon achieving such compression ratio changes to the compression ratio changing method of the present invention, the driving force transmission conditions between the driving source through a worm and Waugh Muhoiru the compression ratio changing mechanism, the drive from a drive source Adjustment control is performed so that the force transmission is suppressed. In this suppression adjustment, the driving force transmission cutoff control may be included. The compression ratio variable engine of the present invention, the driving force transmission conditions between the driving force transmission path to War Muhoiru or al compression ratio changing mechanism, a driving source via a worm and Waugh Muhoiru the compression ratio changing mechanism The adjusting means has an adjusting means for adjusting and controlling the driving force to the side for suppressing the transmission of the driving force.
[0010]
Therefore, an amount corresponding to the driving force transmission status through a worm and War Muhoiru efforts were made to suppress the driving force transmission, the compression ratio changing mechanism side will be able to drive without being warm side constraints. In particular, if the driving force transmission is interrupted, the compression ratio changing mechanism can be driven freely. For this reason, when the above-described suppression of driving force transmission occurs under the condition where the compression ratio is fixed at a high compression ratio in accordance with low load operation, the compression ratio changing mechanism causes the driving force of the driving source to be applied to the combustion pressure. Therefore, the combustion pressure is received in the direction in which the piston is pushed down and the piston top dead center position and the combustion chamber ceiling wall are automatically driven to be in a low compression ratio state. Therefore, according to this invention, the situation where the compression ratio of an engine is maintained carelessly with a high compression ratio can be avoided. As a result, the engine can continue to operate at a low compression ratio, so that knocking can be avoided and drivability can be maintained in a subsequent high-load driving situation, and further, the driver can feel uncomfortable.
[0011]
The above-described variable compression ratio engine of the present invention can be configured as follows. That is, it can be an adjusting means having a clutch that interrupts transmission of driving force between the driving source and the compression ratio changing mechanism. This way, the driving force transmission conditions between the driving source through a worm and Waugh Muhoiru the compression ratio changing mechanism, easily, and can be a situation of rapidly transmission cutoff. Therefore, the compression ratio of the engine can be quickly brought into a low compression ratio state from a fixed state at a high compression ratio, which is beneficial for avoiding knocking.
[0012]
Further, to determine the appropriateness of changing conditions of the compression ratio by determining means, when it is determined that there is an abnormality in the change situation of the compression ratio, the driving of the compression ratio changing mechanism from the driving source through a worm and War Muhoiru It is also possible to control the force transmission to the suppression side. In this way, under conditions where there is no abnormality in the compression change, the compression ratio is changed according to the load condition of the vehicle to improve fuel efficiency and drivability, while the compression ratio is reduced when the compression ratio change is abnormal. By setting the compression ratio, not only knocking avoidance but also drivability can be maintained and a sense of incongruity can be reduced.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, the form of this invention is demonstrated based on an Example. FIG. 1 is an explanatory diagram schematically illustrating the configuration of a variable compression ratio engine 20 according to the first embodiment.
[0014]
As shown in the figure, the variable compression ratio engine 20 includes a cylinder block 22 and a cylinder head 24, and a piston 28 is incorporated in the cylinder 26. The piston 28 is connected to the crankshaft 29 via a connecting rod 27 configured to be bendable, and the vertical reciprocation of the piston 28 in the cylinder is converted into a rotational motion of the crankshaft 29 via the connecting rod 27. The connecting rod 27 constitutes a compression ratio changing mechanism 30 to be described later, and simultaneously changes the top dead center position and the bottom dead center position of the piston 28 through the change of the bending degree. Thereby, the variable compression ratio engine 20 can change the compression ratio. Details of this will be described later.
[0015]
The variable compression ratio engine 20 includes an intake pipe 50 connected to an intake port (not shown) of the cylinder head 24. The intake pipe 50 guides the fuel injected by the injector 52 into the intake pipe flow path to the combustion chamber through an intake port in a mixed state with air. In this case, the air intake amount is adjusted by the throttle valve 54, and the fuel mixture ratio is adjusted.
[0016]
The variable compression ratio engine 20 includes an ECU 60 that controls the compression ratio change, the drive of the throttle valve 54, and the like. The ECU 60 is configured as a logical operation circuit centered on a microcomputer, and in addition to an actuator 63 for driving a throttle valve, a throttle sensor 55, and an accelerator sensor 61, an engine speed and a crank angle sensor for detecting an engine speed and a crank angle. 56, an actuator (servo motor) 57 for changing the compression ratio, a compression ratio sensor 58 for detecting the compression ratio, an oxygen sensor 62 for detecting the oxygen concentration in the exhaust, an air flow meter 64 for detecting the amount of intake air, and the like. ing.
[0017]
Next, a configuration for changing the compression ratio will be described in detail. FIG. 2 is a schematic perspective view showing the compression ratio changing mechanism 30 including the connecting rod 27, and FIG. 3 is an explanatory diagram for explaining how the driving force is transmitted and how the compression ratio is changed in the compression ratio changing mechanism 30.
[0018]
As shown in FIG. 2, the compression ratio changing mechanism 30 is configured by connecting the connecting rod 27 to a first connecting rod 31 and a second connecting rod 32 on the piston 28 side. The first connecting rod 31 is pivotally connected by a piston 28 and a piston pin 34 at a small end portion 33 at an upper portion thereof. The second connecting rod 32 is rotatably connected to a crank pin (not shown) of the crankshaft 29 at the lower end 35 thereof. The first and second connecting rods are connected to each other via a connecting rod pin 36 at the lower end side of the first connecting rod and the upper end side of the second connecting rod, and this connecting portion constitutes a link mechanism. ing.
[0019]
The first connecting rod 31 has a protruding portion 31 a on the lower end side, and is connected to the one end side of the control rod 37 by a pin 38 so as to be rotatable. The control rod 37 is provided with a through hole 37a on the other end side, and a control shaft 39 is rotatably fitted and assembled in the through hole 37a. The link mechanism configured at the connection location of the first and second connecting rods also includes the protrusion 31a and the pin 38, and the control rod 37 is connected to the link mechanism.
[0020]
In addition, the compression ratio changing mechanism 30 has a control shaft guide 40, and rotatably supports the shaft guide on the cylinder block 22 (see FIG. 1). The control shaft guide 40 includes bearing portions 41 having a circular cross section at both ends and a plurality of locations in the middle, and a connecting portion 42 having a crescent cross section formed between adjacent bearing portions 41. The same number of connecting portions 42 as the number of cylinders of the engine are prepared, and the control shaft 39 is fitted and fixed to the control shaft guide 40 so that the control shaft 39 is positioned in the notch region 43 of each connecting portion. That is, the control shaft 39 is fitted and fixed at a position eccentric from the rotation center axis (center axis) X of the control shaft guide 40. Therefore, when the control shaft guide 40 rotates, the control shaft 39 swings with respect to the central axis X and changes its position, whereby the control rod 37 moves the first connecting rod 31 to the second via the pin 38. The connecting rod 32 is bent and displaced. When the connecting rod 27 is bent in this way, the top dead center position and the bottom dead center position length of the piston 28 change simultaneously according to the degree of bending, and the variable compression ratio engine 20 changes the compression ratio. In this case, the compression ratio change, that is, the turning state of the control shaft guide 40 is controlled by the ECU 60 according to the operating state of the engine.
[0021]
The connecting portion 42 has a cross-sectional shape and dimensions so that the control rod 37 does not interfere with the connecting portion 42 when the control shaft 39 swings.
[0022]
Since the variable compression ratio engine 20 causes the control shaft 39 to oscillate (that is, the compression ratio is variable) in the compression ratio changing mechanism 30, the servo motor 57 and the worm gear 47 serving as the actuator are provided as shown in FIG. Have. Further, the variable compression ratio engine 20 includes a clutch 70 in the control shaft guide 40 for transmitting the rotational driving force of the servo motor 57 to the compression ratio changing mechanism 30 side.
[0023]
The clutch 70 is configured as an electromagnetic clutch, and is turned on / off by a control signal from the ECU 60 to switch transmission / disconnection of the motor driving force to the control shaft guide 40. That is, the clutch 70 includes a clutch plate 71 on the worm wheel 49 side of the worm gear 47 and a clutch portion 72 on the control shaft guide 40 side for electromagnetically adsorbing the clutch plate 71.
[0024]
The worm gear 47 includes a worm 48 connected to the shaft of the servo motor 57 and a directly connected worm wheel 49 connected to the control shaft guide 40. Accordingly, the control shaft guide 40 rotates with the rotation of the servo motor 57 in a state where the clutch 70 is connected to the upper and lower shafts (control shaft guide 40). Determined.
[0025]
That is, when the worm 48 is rotated by the servo motor 57, the control shaft guide 40 is rotated by an angle corresponding to the rotation degree, and the control shaft 39 and the control rod 37 are displaced as described above. Due to the displacement of the control rod 37, the bent state of the connecting rod 27 is determined, and the compression ratio of the engine changes. In this embodiment, the control shaft 39 can be displaced around the central axis X of the control shaft guide 40 in a range of 90 ° from the direction of about 3 o'clock to the direction of about 6 o'clock. Is set to be high. Even in this embodiment, since the worm gear 47 having the worm 48 and the worm wheel 49 is used, the anti-reverse action by the worm gear 47 is exhibited.
[0026]
The compression ratio sensor 58 detects the rotation angle (including direction) of the control shaft guide 40 and outputs it to the ECU 60. The ECU 60 is configured to calculate an actual compression ratio based on the sensor output. In calculating the compression ratio, instead of the compression ratio sensor 58 for detecting the rotation angle of the control shaft guide 40, the following configuration may be adopted. That is, an electromagnetic gap sensor can be incorporated in the combustion chamber of the cylinder 26, and the actual compression ratio can be calculated from the sensor output of the piston position in the combustion chamber.
[0027]
Here, how the compression ratio is changed in the variable compression ratio engine 20 of the present embodiment will be described. FIG. 4 is a flowchart showing the compression ratio change control, and FIG. 5 is an explanatory diagram for explaining the contents of the compression ratio control.
[0028]
The compression ratio change control routine shown in FIG. 4 is repeatedly executed every predetermined time. First, an accelerator sensor 61 that reads the engine speed from the speed / crank angle sensor 56 and outputs an accelerator depression state, and a throttle Torque is read according to the sensor output from the sensor 55 or an intake pipe negative pressure sensor (not shown) (step S100). Subsequently, a target compression ratio εt is calculated based on the read rotation speed / torque and the map shown in FIG. 5 in which both are associated with the compression ratio (step S110). A plurality of maps for calculating the target compression ratio are prepared depending on the engine cooling water temperature, the intake air temperature, the emission, or the like, and can be switched as appropriate according to the engine operating condition at that time.
[0029]
Next, the current compression ratio is read from the compression ratio sensor 58 (step S120), and it is determined whether or not the compression ratio needs to be changed based on the coincidence state between the read compression ratio εi and the target compression ratio εt. Determination is made (step S130). If the two compression ratios do not match, it is determined that the compression ratio needs to be changed, and the ECU 60 outputs a change command for setting the compression ratio to the target compression ratio εt to the servo motor 57 (step S140). ). Specifically, a drive signal necessary for setting the current compression ratio εi to the target compression ratio εt is output to the servomotor 57, and the above processes are repeated. By such control, the variable compression ratio engine 20 changes the degree of bending of the connecting rod 27 by the compression ratio changing mechanism 30 using the servo motor 57 as a drive source, and changes the compression ratio of the engine.
[0030]
In the present embodiment, driving force transmission control by the clutch 70 is also performed while performing such compression ratio change control. FIG. 6 is a flowchart showing driving force transmission control using the clutch 70.
[0031]
Even in this driving force transmission control, it is repeatedly executed every predetermined time. First, reading of the operating state of the engine (step S200) and reading of the current compression ratio εi from the compression ratio sensor 58 (step S220) are sequentially performed. . The reading of the operation state is performed by each sensor output as in step S100 described above.
[0032]
Next, it is determined whether or not the read current compression ratio εi is suitable for the current operating state of the engine (step S220). That is, the suitability of the compression ratio is determined based on the matching state between the current engine operating state and the map shown in FIG. In the process in which the compression ratio is changed by the compression ratio change control shown in FIG. 4, the compression ratio is determined to be inappropriate by this step S220. Therefore, in step S220, the compression ratio is determined so as to avoid such a situation. As one method, for example, the transition state of the compression ratio εi from the time when the compression ratio change command output in step S140 in FIG. 4 is grasped, and the suitability is determined by taking the result into consideration. That is, even when the time required from the output of the compression ratio change command to the change of the compression ratio has elapsed, the current compression ratio εi still does not match the target compression ratio, and the change transition of the current compression ratio εi is seen. Appropriateness judgment is performed in consideration of such a situation.
[0033]
If it is determined in step S220 that the compression ratio is suitable, it is determined that each component of the compression ratio changing mechanism 30 is normally driven, and the routine is temporarily terminated without performing any processing. On the other hand, if it is determined that the compression ratio is inappropriate, a disconnection signal is output to the clutch 70, and the clutch 70 disconnects the connection between the worm wheel 49 and the control shaft guide 40 (step S230). Thereafter, an alarm device (not shown) such as a warning light or an alarm device is driven to notify a warning that the compression ratio is inappropriate (step S240), and this routine is terminated. This warning notification is continued until the engine is serviced and reset.
[0034]
As described above, in the variable compression ratio engine 20 of the present embodiment, the compression ratio is variously changed according to the operating state of the engine as described in FIG. 4 and FIG. Whether the compression ratio (actual compression ratio εi) is appropriate or not is determined. If the actual compression ratio εi is not suitable for the actual driving situation, the clutch 70 is disengaged. Therefore, even if some trouble (for example, trouble such as seizure of the servo motor 57) occurs under the condition of a high compression ratio suitable for low-load operation, as described below, This will not cause any particular hindrance to vehicle driving.
[0035]
As described above, when the compression ratio becomes unsuitable (step S220), power transmission between the compression ratio changing mechanism 30 and the servo motor 57 is interrupted by the clutch 70 (step S230), and on the compression ratio changing mechanism 30 side, the compression ratio is reduced. The components (conrod 27, control shaft guide 40, etc.) involved in the change are in a free state. Therefore, in the compression ratio changing mechanism 30, the piston 28 receives the combustion pressure of the combustion chamber fuel, and the connecting rod 27 naturally bends so that the degree of bending of the first connecting rod 31 and the second connecting rod 32 increases. At this time, even the control shaft guide 40 is driven following the bending of the connecting rod. As a result, the compression ratio changing mechanism 30 sets the compression ratio of the engine to a low compression ratio because the piston top dead center position is separated from the ceiling wall of the combustion chamber. Therefore, since the situation where the compression ratio of the engine is inadvertently maintained at the high compression ratio is not caused, the variable compression ratio engine 20 can continue to operate at the low compression ratio. If the compression ratio is thus low, knocking can be avoided, drivability can be maintained, and the driver can feel a sense of discomfort even when the driving condition is high.
[0036]
By the way, the situation where the compression ratio is unsuitable as described above may occur in a situation where the compression ratio is low. However, in this case, since it is already in a low compression ratio state, it will not hinder the subsequent operation. In addition, even if it is a low compression ratio, if the value is a value larger than a low compression ratio lower limit, a compression ratio will be a thing of this low compression ratio lower limit.
[0037]
Further, in this embodiment, when the above-described situation in which the compression ratio is inappropriate occurs, an alarm device such as a warning light or an alarm device is driven to notify the driver that the compression ratio is inappropriate. Therefore, since the driver and the repair contractor can be urged to recover from the failure that has caused such a situation, the compression ratio change failure can be solved in an early stage. For this reason, since the period during which the engine is operated with a low compression ratio can be shortened even in a low-load operation situation, a reduction in fuel consumption due to an operation under a low-load / low compression ratio situation can be suppressed.
[0038]
Further, since the electromagnetic clutch 70 is used to interrupt the transmission of the driving force to the compression ratio changing mechanism 30, the compression ratio changing mechanism 30 can be easily and quickly free. Therefore, since a quick change to a low compression ratio can be performed, knocking can be avoided more effectively.
[0039]
Next, a second embodiment will be described. This embodiment is characterized in that the compression ratio is changed through the vertical movement of the cylinder. FIG. 7 is a schematic exploded perspective view of the variable compression ratio engine 100 according to the second embodiment, and FIG. 8 is a schematic perspective view of the variable compression ratio engine 100.
[0040]
The variable compression ratio engine 100 of the second embodiment changes the compression ratio by moving the cylinder block 103 in the axial direction of the cylinder 102 with respect to the lower case (crankcase) 104. Therefore, the variable compression ratio engine 100 according to the present embodiment includes a compression ratio changing mechanism that moves the cylinder block 103 with respect to the lower case 104. This compression ratio changing mechanism will be described later.
[0041]
Since the cylinder block 103 moves in the axial direction of the cylinder 102 with respect to the lower case 104, the cylinder block 103 moves with respect to the lower case 104 even on a camshaft (not shown) that opens and closes an intake / exhaust valve disposed on the cylinder 102. It becomes. Since the driving force of the camshaft is transmitted from the crankshaft 115 disposed in the lower case 104 via a chain or belt, this is also taken into consideration in the engine of this embodiment. Since this point is not directly related to the gist of the present invention, the description thereof is omitted.
[0042]
Regarding parts other than that the cylinder block 103 is movable with respect to the lower case 104 and that the moving mechanism (compression ratio changing mechanism) is provided, and that the fluctuating force is transmitted to the camshaft. There is no difference from a normal engine. Therefore, description of these is also omitted.
[0043]
As shown in FIG. 7, the variable compression ratio engine 100 includes a plurality of raised portions at the lower portions on both sides of the cylinder block 103, and has a cam storage hole 105 in each raised portion. Five cam storage holes 105 are formed on one side. The cam housing hole 105 has a circular shape, and is perpendicular to the axial direction of the cylinder 102 and parallel to the arrangement direction of the plurality of cylinders 102 (the variable compression ratio engine 100 of this embodiment is a four-cylinder engine). Each is formed to be. The cam storage holes 105 are formed on both sides of the cylinder block 103, and the plurality of cam storage holes 105 on one side are all located on the same axis. The pair of axes of the cam storage holes 105 on both sides of the cylinder block 103 are parallel.
[0044]
The lower case 104 is formed with an upright wall portion so as to be positioned between the plurality of raised portions in which the cam housing holes 105 are formed. A semicircular recess is formed on the surface of each standing wall portion facing the outer side of the lower case 104. Further, a cap 107 to be attached by a bolt 106 is prepared for each standing wall portion, and the cap 107 has a semicircular recess. When the cap 107 is attached to each standing wall portion, a circular bearing housing hole 108 is formed by both members. The shape of the bearing accommodation hole 108 is the same as that of the cam accommodation hole 105 described above.
[0045]
Similar to the cam housing hole 105, the plurality of bearing housing holes 108 are perpendicular to the axial direction of the cylinder 102 and parallel to the arrangement direction of the plurality of cylinders 102 when the cylinder block 103 is attached to the lower case 104. Become. The plurality of bearing housing holes 108 are also formed on both sides of the cylinder block 103, and the plurality of bearing housing holes 108 on one side are all located on the same axis. Four bearing housing holes 108 are formed on one side. The pair of axes of the bearing housing holes 108 on both sides of the cylinder block 103 are parallel. The distance between the cam housing holes 105 on both sides and the distance between the bearing housing holes 108 on both sides are the same.
[0046]
Cam shafts 109 are respectively inserted into the two rows of cam storage holes 105 and bearing storage holes 108 that are alternately arranged. As shown in FIG. 7, the cam shaft 109 includes a cam portion 109b and a movable bearing portion 109c on a shaft portion 109a. The cam portion 109b is fixed to the shaft portion 109a while being eccentric with respect to the central axis of the shaft portion 109a, and has a regular circular cam profile. The movable bearing portion 109c has the same outer shape as the cam portion 109b and is rotatably attached to the shaft portion 109a. In the present embodiment, the cam portions 109b and the movable bearing portions 109c are alternately arranged. The pair of cam shafts 109 have a mirror image relationship with the cylinder 102 interposed therebetween. An attachment portion 109d of a clutch 120, which will be described later, is formed at the end of the cam shaft 109. The center axis of the shaft portion 109a and the center of the mounting portion 109d are eccentric, and the center of all the cam portions 109b and the center of the mounting portion 109d coincide.
[0047]
The movable bearing portion 109c is also eccentric with respect to the shaft portion 109a, and the amount of eccentricity is the same as that of the cam portion 109b. In order to actually construct the camshaft 109, the camshaft 109 is manufactured in a state in which one end of the cam portion 109b is integrally connected in advance, and the movable bearing portion 109c, the other cam portion 109b, Are inserted alternately. Only the cam portion 109b is fixed to the shaft portion 109a with a screw or the like as shown. In this case, the cam portion may be fixed by other methods such as press-fitting or welding. The number of cam portions 109b on the shaft portion 109a matches the number of cam housing holes 105 on one side of the cylinder block 103. Further, the thickness of the cam portion 109b also matches the length of each corresponding cam storage hole 105. Similarly, the number of movable bearing portions 109c on the shaft portion 109a matches the number of bearing housing holes 108 formed on one side of the lower case 104. Further, the thickness of the movable bearing portion 109c also matches the length of the corresponding bearing housing hole 108.
[0048]
In each cam shaft 109, the eccentric directions of the plurality of cam portions 109b are the same. In addition, since the outer shape of the movable bearing portion 109c is the same circle as the cam portion 109b, the outer surface of the plurality of cam portions 109b and the outer surface of the plurality of movable bearing portions 109c are rotated by rotating the movable bearing portion 109c. Can be matched. In this state, the cylinder block 103 and the lower case 104 are combined, and the cam shaft 109 is inserted into a long hole formed by the plurality of cam housing holes 105 and the plurality of bearing housing holes 108 and assembled. The cap 107 may be attached after the camshaft 109 is disposed with respect to the cylinder block 103 and the lower case 104.
[0049]
The cam housing hole 105, the bearing housing hole 108, the cam portion 109b, and the movable bearing portion 109c have the same exact circular shape. The cylinder block 103 is slidable with respect to the lower case 104, but a member such as a piston ring that secures the airtightness between the cylinder inner surface and the piston is arranged on the sliding surface of both of them so as to be airtight. Secure. Sealing may be performed by a method other than the piston ring, for example, a rubber gasket such as an O-ring.
[0050]
Each camshaft 109 has a clutch 120 at one end of its shaft portion 109a. The clutch 120 is also configured as an electromagnetic clutch, similar to the clutch 70 described above, and switches between transmission and disconnection of the motor driving force to each camshaft 109. That is, the clutch 120 has a clutch plate 121 on the worm wheel 110 side and a clutch portion 122 on the camshaft 109 side for electromagnetically adsorbing it. The worm wheel 110 is positioned with a key and is bolted to the clutch plate 121 of the clutch 120.
[0051]
Each worm wheel 110 corresponding to the pair of cam shaft 109, warm 1 11a, 111b are engaged. Warm 1 11a, 111b is attached to the output shaft of the single motor 112. Warm 1 11a, 111b has a butterfly旋溝rotating in opposite directions. Therefore, when the motor 112 is rotated while the clutch 120 is in a driving force transmission state, the pair of cam shafts 109 receives the rotation of the worm wheel 110 via the clutch 120 and rotates in opposite directions. The motor 112 is fixed to the cylinder block 103 or the like and moves integrally with the cylinder block 103.
[0052]
Next, compression ratio control performed by the variable compression ratio engine 100 of the present embodiment will be described. FIG. 9 is an explanatory diagram for explaining the compression ratio change in the variable compression ratio engine 100. 9A to 9C are cross-sectional views showing the compression ratio changing mechanism including the cylinder block 103, the lower case 104, and the cam shaft 109 and the like constructed between them. In these drawings, the central axis of the shaft portion 109a is denoted by a, the center of the cam portion 109b is denoted by b, and the center of the movable bearing portion 109c is denoted by c.
[0053]
FIG. 9A shows a state in which the outer circumferences of all the cam portions 109b and the movable bearing portions 109c coincide with each other when viewed from the extension line of the shaft portion 109a. At this time, the pair of left and right shaft portions 109a are located outside the cam housing hole 105 and the bearing housing hole 108 here.
[0054]
When the shaft portion 109a (and the cam portion 109b fixed to the shaft portion 109a) is driven in the direction of the arrow by driving the motor 112 from the state of FIG. 9A, the state of FIG. 9B is obtained. At this time, since the cam portion 109b and the movable bearing portion 109c are displaced in the eccentric direction with respect to the shaft portion 109a, the cylinder block 103 can be slid toward the top dead center side with respect to the lower case 104. The sliding amount is maximized when the cam shaft 109 is rotated until the state shown in FIG. 9C is reached, and is twice the eccentric amount of the cam portion 109b and the movable bearing portion 109c. The cam portion 109b and the movable bearing portion 109c rotate inside the cam housing hole 105 and the bearing housing hole 108, respectively, and allow the position of the shaft portion 109a to move inside the cam housing hole 105 and the bearing housing hole 108, respectively. is doing.
[0055]
In the state where the cam portion 109b and the movable bearing portion 109c completely coincide (FIG. 9A), the plurality of movable bearing portions 109c attached to one cam shaft 109 slide the cylinder up and down. There is also a possibility that it will run idle. For this reason, the engine compression ratio changing mechanism of the present embodiment does not cause a state in which the cam portion 109b and the movable bearing portion 109c are completely matched as shown in FIG. 9A. For example, when the rotational position of the cam shaft 109 in the state of FIG. 9A is set to 0 ° as a reference (the forward direction is the reverse rotational direction with the pair of cam shafts 109), the rotational position in the state of FIG. However, if the actual control range is set to 5 ° or more, the above-described problems can be solved. Further, as described above, since the actual amount of the slinod of the cylinder block 103 is considered to be several mm, about 0 ° ± 5 ° (also about 180 ° ± 5 °) cannot be used. There is no problem.
[0056]
Further, in this embodiment, the cylinder block 103 is slid only to the top dead center side with respect to the lower case 104 and used. Further, in order to return the slide amount to 0 from the state of FIG. 9C, the motor 112 is reversely rotated to return to the state of FIG. 9A. That is, in this embodiment, the control range of the cam shaft 109 is 5 ° to 90 °. However, the cylinder block 103 may be slid only to the bottom dead center side with respect to the lower case 104. In this case, the control range of the cam shaft 109 may be -5 ° to -90 ° (355 ° to 270 °). Further, when the cylinder block 103 is slid only to the top dead center side with respect to the lower case 104, the control range of the cam shaft 109 may be set to 90 ° to 175 ° or the like.
[0057]
By using the compression ratio changing mechanism as described above, the cylinder block 103 can be slid in the axial direction of the cylinder 102 with respect to the lower case 104. As a result, the compression ratio can be variably controlled. When a variable amount of the compression ratio was calculated by realizing a sliding amount of several mm with an engine of a certain size, it was calculated that a variable range of about 9 to 14.5 could be secured. Further, according to such a compression ratio changing mechanism, since the cylinder is not tilted, there is no portion where an excessive moment due to the combustion pressure is applied, and a simple operation using the camshaft 109 or the like is provided. The mechanism can build a variable compression ratio engine. Even in this embodiment, since the worm wheel 110 and the warm 1 11a, the worm gear structure having a 111b are incorporated, as in the first embodiment, the reverse rotation stop action is exhibited.
[0058]
Even in the variable compression ratio engine 100 of the second embodiment described above, as in the variable compression ratio engine 20 described above, the compression ratio is set according to the operating state of the engine as described in FIGS. While making various changes, the suitability of the changed compression ratio (actual compression ratio εi) is determined as shown in FIG. If the actual compression ratio εi is not suitable for the actual driving situation, the clutch 120 is simultaneously disconnected for each camshaft 109. Therefore, the same effect as the first embodiment can be obtained.
[0059]
In the second embodiment, in a situation where the compression ratio is inappropriate, the power transmission of the motor 112 is interrupted by the clutch 120, and the constituent members involved in the compression ratio change (the cam portion 109b of the cam shaft 109, the movable bearing portion 109c, etc.) Become free. Therefore, the piston receives the combustion pressure of the combustion chamber fuel, and the cam portion 109b and the movable bearing portion 109c lift the cylinder block 103 with respect to the lower case 104 as shown in FIG. A low compression ratio is achieved.
[0060]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and embodiments, and can of course be implemented in various modes without departing from the gist of the present invention. is there.
[0061]
For example, in the second embodiment described above, the compression ratio changing mechanism is constructed by combining the cam portion 109b-cylinder block 103 and the movable bearing portion 109c-lower case 104. However, the cam portion-lower case, movable bearing portion-cylinder block A compression ratio changing mechanism may be constructed in combination. Further, the shape of the cam portion 109b is preferably a perfect circle, but it can function even if it is not a perfect circle. For example, in the above-described embodiment, even if the major axis is an ellipse or an oval having the same length as the cam portion 109b, it can function.
[0062]
Furthermore, the variable compression ratio engine of the second embodiment can be easily applied to a V-type engine. In this case, the pair of cam shafts described above may be disposed for each bank, or a pair of cam shafts may be disposed at the bases of both banks so that a V-shape is formed in the center direction of the central angle formed by both banks. The compression ratio may be changed by sliding the entire bank.
[0063]
In addition, a clutch that switches the transmission of motor driving force to the transmission / cut-off state has been described as an example, but a clutch configuration with variable transmission efficiency and a configuration that can adjust the transmission of the motor driving force including shut-off are provided. If it exists, it can replace with the clutch 70 and clutch 120 of said Example, and can be used.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram schematically illustrating the configuration of a variable compression ratio engine 20 according to a first embodiment.
FIG. 2 is a schematic perspective view showing a compression ratio changing mechanism 30 including a connecting rod 27. FIG.
FIG. 3 is an explanatory diagram for explaining how the driving force is transmitted and how the compression ratio is changed in the compression ratio changing mechanism 30;
FIG. 4 is a flowchart showing compression ratio change control.
FIG. 5 is an explanatory diagram for explaining the content of compression ratio control.
6 is a flowchart showing driving force transmission control using a clutch 70. FIG.
FIG. 7 is a schematic exploded perspective view of a variable compression ratio engine 100 according to a second embodiment.
FIG. 8 is a schematic perspective view of the variable compression ratio engine 100. FIG.
FIG. 9 is an explanatory diagram for explaining a change in compression ratio in the variable compression ratio engine 100. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 ... Variable compression ratio engine 22 ... Cylinder block 24 ... Cylinder head 26 ... Cylinder 27 ... Connecting rod 28 ... Piston 29 ... Crankshaft 30 ... Compression ratio change mechanism 31 ... 1st connecting rod 31a ... Projection part 32 ... 2nd connecting rod 33 ... Small End 34 ... Piston pin 35 ... Large end 36 ... Connecting rod pin 37 ... Control rod 37a ... Through hole 38 ... Pin 39 ... Control shaft 40 ... Control shaft guide 41 ... Bearing portion 42 ... Connecting portion 43 ... Notch region 47 ... Worm gear 48 ... Worm 49 ... Worm wheel 50 ... Intake pipe 52 ... Injector 54 ... Throttle valve 55 ... Throttle sensor 56 ... Rotation speed / crank angle sensor 57 ... Servo motor 58 ... Compression ratio sensor 61 ... Accelerator sensor 62 ... Oxygen sensor DESCRIPTION OF SYMBOLS 3 ... Actuator 64 ... Air flow meter 70 ... Clutch 71 ... Clutch plate 72 ... Clutch part 100 ... Variable compression ratio engine 102 ... Cylinder 103 ... Cylinder block 104 ... Lower case 105 ... Cam accommodation hole 106 ... Bolt 107 ... Cap 108 ... Bearing accommodation hole 109 ... cam shaft 109a ... shaft portion 109b ... cam portion 109c ... movable bearing portion 109d ... mounting portion 110 ... worm wheel 111a, 111b ... warm <br/> 112 ... motor 115 ... crankshaft 120 ... clutch 121: clutch plate 122 ... Clutch part X ... Rotation center axis

Claims (3)

A compression ratio changing mechanism having a drive device driven against the combustion pressure in the combustion chamber to change the compression ratio of the engine; a drive source for generating a driving force for changing the compression ratio; and A method for changing a compression ratio of an engine comprising: a worm that rotates by receiving a driving force; and a worm wheel that meshes with the worm and transmits the driving force to the driving device of the compression ratio changing mechanism,
The driving force transmission conditions between the driving source and the compression ratio changing mechanism through said worm and Waugh Muhoiru, when there is an abnormality in the change situation of the compression ratio by said compression ratio changing mechanism, from said drive source A method for changing the compression ratio of an engine, wherein adjustment control is performed so that transmission of the driving force is suppressed. An engine that can change the compression ratio of the engine,
A compression ratio changing mechanism having a drive device driven against the combustion pressure in the combustion chamber to change the compression ratio of the engine;
A driving source for generating a driving force for changing the compression ratio;
A worm that rotates under the driving force of the driving source;
A worm wheel that meshes with the worm and transmits the driving force to the compression ratio changing mechanism;
Wherein the driving force of the driving source is transmitted to the compression ratio changing mechanism through said worm and War Muhoiru, and a control means for changing the driving device drives and controls the compression ratio of the compression ratio changing mechanism,
The control means includes
In the driving force transmission path to the War Muhoiru or al the compression ratio changing mechanism, the driving force transmission conditions between the driving source and the compression ratio changing mechanism through said worm and War Muhoiru, the drive source Adjusting means for adjusting and controlling the driving force transmission from the side ,
A determination means for determining whether the change ratio of the compression ratio is appropriate;
If it is determined that there is an abnormality in the change situation of the compression ratio, by the adjusting means, you suppression control a driving force transmission to the compression ratio changing mechanism from the driving source through said worm and worm wheel, Variable compression ratio engine. A variable compression ratio engine according to claim 2 Symbol placement,
The compression ratio variable engine, wherein the adjusting means includes a clutch that interrupts transmission of driving force between the driving source and the compression ratio changing mechanism.

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