JP4421482B2 - Variable compression ratio mechanism for internal combustion engines - Google Patents

Description

  The present invention relates to an engine compression ratio variable mechanism that variably controls a compression ratio of an internal combustion engine (hereinafter referred to as an engine).

  Generally, when the load applied to the engine is low, less fuel is sucked into the cylinder, so the temperature and pressure in the cylinder are low when the piston is located near top dead center, and combustion stability is low. descend. For this reason, the compression ratio is increased to improve the stability of combustion, and the expansion ratio is increased to improve the thermal efficiency, thereby reducing the fuel consumption. On the other hand, when the load applied to the engine increases, the amount of fuel sucked into the cylinder increases, the temperature in the cylinder rises, and knocking occurs. In order to prevent the occurrence of knocking, there is known a variable compression ratio mechanism that increases the compression ratio when the engine load is small and controls the compression ratio low when the engine load is large (for example, Patent Documents). 1-3).

  In this variable compression ratio mechanism, a lower link is rotatably attached to the crank pin of the crankshaft, one end of the upper link linked to the piston pin is linked to a part of the lower link, and a control shaft having an eccentric cam is provided. Arranged in parallel with the crankshaft, the other end of the control link, one end of which is linked to the other part of the lower link, is linked to the eccentric cam of the control shaft, and the actuator is driven in a predetermined rotation range to control the compression ratio. I can do it. Here, an actuator using, for example, an electric motor as a drive source of a control shaft is known. The rotational motion of the electric motor is converted into a linear motion of the reciprocator, and this linear motion is converted into a rotational motion of the control shaft.

  A conventional compression ratio variable mechanism is configured to detect an angular position of a control shaft that is rotationally controlled by an actuator by a position sensor (angle sensor), and to control the compression ratio based on the detected value.

JP 2002-115571 A JP 58-57040 A Japanese Patent Publication No. 4-28893

  Since the conventional compression ratio variable mechanism is configured as described above, it has the following problems. First, since the control shaft is disposed in parallel with the crankshaft at the bottom of the engine, it is difficult to secure an installation location for attaching an angle sensor for detecting the angular position of the control shaft. That is, even if the angle sensor is to be attached to the end of the control shaft, the installation location cannot be secured because it is in the vicinity of the crank pulley. In addition, since the angle sensor is attached to the control shaft that controls the compression ratio, it is possible to detect the position of the control shaft with high accuracy. However, the rotational motion of the electric motor is once converted into linear motion, and then the control shaft is Therefore, the relationship between the value detected by the angle sensor and the rotational speed of the electric motor becomes a non-linear function. That is, for example, even if the electric motor moves by the same number of rotations and rotates the control shaft, the amount of change differs depending on the change range of the compression ratio, and it is difficult to accurately adjust the predetermined compression ratio.

  Conventionally, other variable compression ratio mechanisms (see, for example, Patent Documents 2 and 3) are also known. However, these variable compression ratio mechanisms are all variable compression ratios of the type described in Patent Document 1 above. The mechanism is not assumed. In the variable compression ratio mechanism described in Patent Document 1, the angle of the control shaft is detected by an angle sensor provided outside the actuator, and a technique for controlling the compression ratio by other sensors is known. Not.

  The present invention has been made in order to overcome the drawbacks of the conventional variable compression ratio mechanism of an engine. The object of the present invention is to install an angle sensor for detecting the angular position of the control shaft outside the actuator. The object is to provide a variable compression ratio mechanism in which the engine specification change is minimal and the compression ratio is variably controlled with high accuracy.

An engine compression ratio variable mechanism according to the present invention includes a lower link that is externally fitted to a crank pin so as to be relatively rotatable, an upper link that links the lower link and the piston pin, and a cylinder block formed in a cylinder block. An engine compression ratio variable mechanism having an extended control shaft, an eccentric cam eccentrically provided on the control shaft, and a control link linking the eccentric cam and the lower link is variably controlled. an actuator and a rotational driving force transmitting means for transmitting the rotational driving force from the reciprocating means and the rotation driving means mechanically linked to the rotation of the control shaft Previous Symbol reciprocating means, provided in the actuator and it is obtained by a detecting means for detecting the amount of movement of the actuator during rotation of the front Symbol control shaft.

According to the present invention, a lower link that is externally fitted to the crank pin so as to be relatively rotatable, an upper link that links the lower link and the piston pin, a control shaft that is formed in the cylinder block and extends in the column direction of the cylinder, an eccentric cam eccentrically provided on the control shaft, the variable compression ratio mechanism of an engine and a control link that links the said lower link and the eccentric cam, the control shaft to variably control the compression ratio of the engine times an actuator having a rotational drive force transmission means for transmitting a rotational driving force from the rotary drive means into a reciprocating means for mechanically linked to movement of the actuator when provided and rotated before Symbol control shaft in the actuator And detecting means for detecting the amount of movement, by detecting the amount of movement of the actuator by the detecting means, To change linearly compression ratio than conventional relative movement amount, there is an effect that it is possible to variably control facilitates precision compression ratio. In addition, since the compression ratio can be controlled by the amount of movement of the actuator detected by the detection means built in the actuator, there is no need to provide a sensor outside the actuator as in the prior art, so the engine specifications are changed. There is an effect that the mountability can be improved.

Embodiment 1 FIG.
1 is a partial sectional view showing a linkage mechanism of an engine compression ratio variable mechanism according to Embodiment 1 of the present invention, and FIG. 2 is a partial sectional view showing an internal structure of an actuator in the variable compression ratio mechanism shown in FIG. FIG. 3 is a graph showing the relationship between the output of the detection means provided in the actuator shown in FIG. 2 and the motor rotation speed of the actuator.

  A cylindrical cylinder 3 is formed in the cylinder block 1, and a piston 5 is disposed in the cylinder block 1 so as to be reciprocally movable. The piston pin 7 of the piston 5 and the crankpin 11 of the crankshaft 9 are mechanically linked via a multi-link variable compression ratio mechanism. The variable compression ratio mechanism includes a lower link 13 that is externally fitted to the crank pin 11 so as to be relatively rotatable, an upper link 15 that links the lower link 13 and the piston pin 7, and a cylinder 3 formed in the cylinder block 1. A control shaft 17 extending in the column direction, an eccentric cam 19 provided eccentric to the control shaft 17, a control link 21 linking the eccentric cam 19 and the lower link 13, and a control shaft 17 rotating within a predetermined range. An actuator (see FIG. 2) 23 that is dynamically driven and held at a predetermined rotational position is schematically configured.

  An upper end portion of the upper link 15 is connected to the piston pin 7 so as to be relatively rotatable, and a lower end portion is connected to the lower link 13 via a connecting pin 25 so as to be relatively rotatable. One end of the control link 21 is connected to the lower link 13 via a connecting pin 27 so as to be relatively rotatable, and the other end is externally fitted to the eccentric cam 19 so as to be relatively rotatable. A control plate 29 is provided integrally with the control shaft 17, and a slit 31 is formed in the control plate 29 from the peripheral edge toward the control shaft 17. As shown in FIGS. 1 and 2, a pin 35 of a reciprocator (reciprocating means) 33 of the actuator 23 is slidably engaged with the slit 31. The posture of the linkage mechanism is determined by the position of the pin 35 adjusted by the actuator 23, and the relative position of the piston 5 with respect to the cylinder 3 is determined, whereby compression in a combustion chamber (not shown) formed above the piston 5 is determined. The ratio is configured to be controlled. Note that arrows A1 to A7 and arrows B1 to B7 in FIG. 1 represent the operation directions of the components of the engine and the linkage mechanism.

  The actuator 23 has a pin 35 at one end and a reciprocating element 33 having a male screw 37 on the other end surface, an electric motor (rotation drive means) 39 as a drive source, and a motor pinion shaft of the electric motor 39. The three gears 45, 47, and 49 (rotational driving force transmitting means) that transmit the rotational driving force from the gear 43 provided in 41, and the male screw 37 of the reciprocator 33 formed on the inner surface of the gear 49. And a female screw (rotation driving force transmission means) 51 that is configured. The reciprocator 33 is slidably disposed in a substantially cylindrical housing 53, and a case 55 coupled to the housing 53 with a fastening member (not shown) such as a bolt, and a bolt 55 or the like connected to the case 55. A gear 43 of the motor pinion shaft 41 of the electric motor 39 and three gears 45, 47 and 49 are accommodated in a space formed between the cover 57 and a cover 57 connected by a fastening member (not shown). The cover 57 is formed with an inner space 59 that can be accommodated on the other end side of the reciprocator 33. Further, an opening 61 for receiving the penetration of the motor pinion shaft 41 of the electric motor 39 is formed in a part of the cover 57, and the electric motor 39 is bolted to the outer surface of the cover 57 around the opening 61. It is fixed with fastening members (not shown) such as.

The electric motor 39 is a brushless motor, and has a built-in hall IC 63 for driving that controls the rotation of the motor pinion shaft 41. In the first embodiment, the driving Hall IC 63 uses the rotation speed of the electric motor 39 (the amount of movement of the actuator) as detection means. When the electric motor 39 is turned on, the drive Hall IC 63 starts counting the rotation of the motor pinion shaft 41 (the amount of movement of the actuator). This count range is a control shaft that defines the maximum and minimum values of the compression ratio by the position of the pin 35 of the reciprocator 33 that moves in the direction of the arrow X or Y by the rotational driving force transmitted from the motor pinion shaft 41. 17 corresponding to the rotation range. That is, the correspondence between the count range and the compression ratio range is calculated and determined by a CPU (not shown). Here, the rotational speed of the motor pinion shaft 41 of the electric motor 39 and the detection value (sensor output) of the driving Hall IC 63 are linear functions as shown in FIG. The ratio is a function that is closer to the linearity compared to the conventional example for the reason described later, so the compression ratio can be easily and accurately controlled with linear feedback control by a driver (not shown) based on the sensor output. It becomes possible to do.
Here, the reason why the rotation speed and the compression ratio of the electric motor 39 are functions that are more linear than the conventional example will be described.
In the conventional example, as shown in FIG. 7, the change in the compression ratio is nonlinear with respect to the rotation angle of the control shaft. This is because the piston position in the cylinder linearly translates with respect to the rotation of the eccentric cam integrated with the control shaft in the multi-link variable compression ratio mechanism as in the present invention. The moving angle and the compression ratio exhibit nonlinear characteristics. Accordingly, since the change in the compression ratio with respect to the sensor output disposed at the end of the control shaft is also non-linear, the amount of change in the compression ratio per unit angle of the control shaft is not constant, making it difficult to control the compression ratio.
On the other hand, in the present invention, as shown in FIG. 8, the change in the compression ratio with respect to the detection value (sensor output) of the driving Hall IC 163 is significantly linearized, particularly on the high compression ratio side, as compared with the conventional example. I understand. This is because the linear motion of the actuator driving means (reciprocator) is converted into the rotational motion of the control shaft, and further converted back into a linear change in the piston position.
In the control shaft rotation range, there is a surface where nonlinearity is promoted compared to the conventional example on the low compression ratio side, but in the multi-link variable compression ratio mechanism to which the present invention is applied, the control shaft angle Since the compression ratio change sensitivity with respect to is relatively low on the low compression ratio side, precise compression ratio control is unnecessary, and there is little influence on the output performance of the internal combustion engine.
In an internal combustion engine using a variable compression ratio mechanism to which the present invention is applied, in order to avoid knocking particularly in a high load region, it can be changed from a high compression ratio to a low compression ratio immediately and accurately to a desired compression ratio. It is important to work. Compared to the conventional example, the ease of control on the high compression ratio side is also effective in terms of avoiding knocking and the like.

  Here, the compression ratio control accuracy in the case of controlling based on the rotational speed of the electric motor 39 and the case of controlling based on the angle sensor output of the control shaft will be described. That is, the motor pinion shaft 41 of the electric motor 39 receives a large load from the engine side as a backlash via the linkage mechanism such as the control shaft 17. This error factor such as backlash certainly causes an error in the detection value by the driving Hall IC 63, and can be regarded as a demerit when the driving Hall IC 63 is used as a detecting means. However, the gear ratio in the actuator 23 with respect to the rotation range of the control shaft 17 that defines the range of the compression ratio is large. Here, a large gear ratio means that, for example, when the motor pinion shaft 41 of the electric motor 39 rotates 10,000 times, the control shaft 17 rotates by several degrees, and the corresponding piston 5 moves about several millimeters. Means to give a predetermined compression ratio. At this time, even if the motor pinion shaft 41 is deviated by about a half turn due to the influence of backlash, it can be approximated that the motor pinion shaft 41 has made about 10,000 rotations. There is no substantial variation in the result of the piston 5 moving about a few millimeters giving a predetermined compression ratio. Therefore, the influence of the error factors such as the backlash can be ignored at the time of detection by the driving Hall IC 63, and therefore, the compression ratio control accuracy has the same level as the conventional example.

Next, the operation will be described.
When the electric motor 39 rotates, the rotation of the motor pinion shaft 41 is transmitted to the gears 43, 45, 47 and 49, and the female screw 51 of the gear 49 rotates around the male screw 37 of the reciprocator 33. Thereby, the reciprocator 33 slides in the arrow X direction or the Y direction depending on the rotation direction of the electric motor 39. When the reciprocator 33 slides in the direction of the arrow X, the pin 35 protrudes from the housing 53, and the pin 35 slides inward of the slit 31 to move the control shaft 17 together with the control plate 29 in the direction of arrow B7. Rotate. By this rotation, the eccentric cam 19 moves in the direction of the arrow B6, and accordingly, the control link 21 moves down in the direction of the arrow B5 to rotate the crank pin 11 in the direction of the arrow B4 and push up the lower link 13 in the direction of the arrow B3. Thus, the upper link 15 is pushed up in the direction of the arrow B2, and the position of the piston 5 in the cylinder 3 is raised in the direction of the arrow B1. This guides the engine to the high compression ratio side.

  Further, when the electric motor 39 rotates in the reverse direction, the reciprocator 33 slides in the arrow Y direction. In this case, the pin 35 is pulled into the housing 53, and the control shaft 17 is rotated in the direction of the arrow A7 together with the control plate 29 while the pin 35 slides outward of the slit 31. By this rotation, the eccentric cam 19 moves in the direction of the arrow A6, and accordingly, the control link 21 goes up in the direction of the arrow A5, rotates the crankpin 11 in the direction of the arrow A4, and pushes down the lower link 13 in the direction of the arrow A3. Thus, the upper link 15 is pushed down in the direction of arrow A2, and the position of the piston 5 in the cylinder 3 is lowered in the direction of arrow A1. This guides the engine to the low compression ratio side.

  On the other hand, the rotation of the electric motor 39 is counted and monitored by the driving Hall IC 63. The correspondence between the count range and the compression ratio range is calculated and determined by a CPU (not shown). The electric motor 39 is driven by a driver (not shown) based on the detection value (sensor output) of the driving Hall IC 63 to perform feedback control closer to linear than in the conventional example, and variably control the compression ratio.

  As described above, according to the first embodiment, the reciprocator 33 mechanically linked to the rotation of the control shaft 17, the electric motor 39, and the rotational driving force from the electric motor 39 to the reciprocator 33. An actuator 23 having transmission gears 43, 45, 47 and 49, and a drive hall IC 63 provided in the actuator 23 and detecting the rotation speed of the electric motor 39 when the control shaft 17 rotates. Since the rotational speed of the electric motor 39 is detected by the drive Hall IC 63, the compression ratio that changes with characteristics closer to linearity than the conventional example is variably controlled with respect to this rotational speed. There is an effect that can be.

  According to the first embodiment, since the drive Hall IC 63 originally built in the electric motor 39 is used as the detection means for the drive control, the sensor is provided outside the actuator as in the prior art. Since there is no need to provide a separate component, the number of components can be reduced, and there is an effect that mountability can be significantly improved, such as no need to change engine specifications.

Embodiment 2. FIG.
4 is a partial cross-sectional view showing an internal structure of an actuator in an engine compression ratio variable mechanism according to Embodiment 2 of the present invention. Of the constituent elements in the second embodiment, those common to the constituent elements in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  A feature of the second embodiment is that a rotation speed sensor (detection means) 65 for detecting the rotation speed of the electric motor 39, that is, the rotation speed of the gear 43 of the motor pinion shaft 41 (movement amount of the actuator) is provided in the case 55. It is in the point. The detection value (sensor output) by the rotation speed sensor 65 is also affected by error factors such as backlash similarly to the detection value by the driving Hall IC 63 in the first embodiment, but the influence is small. For this reason, since a linear function is established between the detection value by the rotation speed sensor 65 and the compression ratio, the compression ratio can be linearly feedback-controlled based on the detection value by the rotation speed sensor 65. Become.

  As described above, according to the second embodiment, since the rotation speed sensor 65 for detecting the rotation speed of the gear 43 of the motor pinion shaft 41 is provided in the actuator 23, the detection value by the rotation speed sensor 65 is detected. In contrast, the compression ratio that changes linearly can be variably controlled with high accuracy.

  According to the second embodiment, since the rotational speed sensor 65 is provided in the actuator 23, unlike the conventional variable compression ratio mechanism attached to the outside of the actuator, changes in the engine specifications can be minimized. There is an effect that the mountability can be remarkably improved.

Embodiment 3 FIG.
FIG. 5 is a partial cross-sectional view showing the internal structure of the actuator in the engine compression ratio variable mechanism according to Embodiment 3 of the present invention. Of the constituent elements in the third embodiment, those common to the constituent elements in the first embodiment and the like are denoted by the same reference numerals, and description thereof is omitted.

  The feature of the third embodiment is that a rotation speed sensor (detection means) for detecting the rotation speed (movement amount of the actuator) of a gear 49 as a rotational driving force transmission means for connecting the rotation of the electric motor 39 to the sliding movement of the reciprocator 33. ) 67 is provided in the case 55. The detection value (sensor output) by the rotational speed sensor 67 is also affected by an error factor such as backlash similarly to the detection value by the driving Hall IC 63 in the first embodiment, but the influence is small. For this reason, since a linear function is established between the detection value by the rotation speed sensor 67 and the compression ratio, the compression ratio can be linearly feedback-controlled based on the detection value by the rotation speed sensor 67. Become.

  As described above, according to the third embodiment, since the rotation speed sensor 67 for detecting the rotation speed of the gear 49 is provided in the case 55, it is linear with respect to the detection value by the rotation speed sensor 67. The compression ratio can be variably controlled with high accuracy.

  According to the third embodiment, since the rotational speed sensor 67 is provided in the actuator 23, unlike the conventional variable compression ratio mechanism attached outside the actuator, changes in the engine specifications can be suppressed to a minimum. There is an effect that the mountability can be remarkably improved.

Embodiment 4 FIG.
FIG. 6 is a partial cross-sectional view showing the internal structure of the actuator in the engine compression ratio variable mechanism according to Embodiment 4 of the present invention. Of the constituent elements in the fourth embodiment, those common to the constituent elements in the first embodiment and the like are denoted by the same reference numerals, and description thereof is omitted.

  The feature of the fourth embodiment is that a linear sensor 69 for detecting the moving distance (movement amount of the actuator) of the reciprocator is provided at the other end of the reciprocator 33. As the linear sensor 69, any known sensor can be used as long as it can measure the moving distance of the reciprocator 33. For example, the stroke can be measured by a method such as voltage change, flux change, sliding resistance, or laser irradiation. Things can be mentioned. The detection value by the linear sensor 69 is also affected by an error factor such as backlash similarly to the detection value by the driving Hall IC 63 in the first embodiment, but the influence is small. For this reason, since a linear function is established between the detection value by the linear sensor 69 and the compression ratio, the compression ratio can be linearly feedback-controlled based on the detection value by the linear sensor 69.

  As described above, according to the fourth embodiment, the linear sensor 69 that detects the movement distance (movement amount of the actuator) of the reciprocator is provided at the other end of the reciprocator 33. The compression ratio that changes linearly with respect to the detected value can be variably controlled with high accuracy.

  In the fourth embodiment, the linear sensor 69 is arranged so as to protrude from the cover 57 to the outside. However, since the linear sensor 69 itself is smaller than the size of the actuator 23, the specification of the engine is used. There is an effect that the change can be made unnecessary.

It is a fragmentary sectional view which shows the linkage mechanism of the compression ratio variable mechanism of the engine by Embodiment 1 of this invention. It is a fragmentary sectional view which shows the internal structure of the actuator in the compression ratio variable mechanism shown in FIG. It is a graph which shows the relationship between the output of the detection means provided in the actuator shown in FIG. 2, and the motor rotation speed of an actuator. It is a fragmentary sectional view which shows the internal structure of the actuator in the compression ratio variable mechanism of the engine by Embodiment 2 of this invention. It is a fragmentary sectional view which shows the internal structure of the actuator in the compression ratio variable mechanism of the engine by Embodiment 3 of this invention. It is a fragmentary sectional view which shows the internal structure of the actuator in the compression ratio variable mechanism of the engine by Embodiment 4 of this invention. It is a characteristic view which shows the change of the compression ratio with respect to the rotation angle of a control shaft. It is a characteristic view which shows the change of the compression ratio with respect to a drive hole.

Explanation of symbols

  1 cylinder block, 3 cylinder, 5 piston, 7 piston pin, 9 crankshaft, 11 crankpin, 13 lower link, 15 upper link, 17 control shaft, 19 eccentric cam, 21 control link, 23 actuator, 25 connecting pin, 27 Connecting pin, 29 Control plate, 31 Slit, 33 Reciprocator (reciprocating means), 35 Pin, 37 Male screw, 39 Electric motor (rotational driving means), 41 Motor pinion shaft, 43 Gear (rotational driving force transmitting means), 45 Gear (Rotation drive force transmission means), 47 Gears (Rotation drive force transmission means), 49 Gears (Rotation drive force transmission means), 51 Female screw (Rotation drive force transmission means), 53 Housing, 55 Case, 57 Cover, 59 Inner space 61 Opening 63 Drive Hall IC (detection means) 65 Rolling speed sensor (detection means), 67 rpm sensor (detection means), 69 linear sensor (detecting means).

Claims (5)

A lower link that is externally fitted to the crank pin so as to be relatively rotatable, an upper link that links the lower link and the piston pin, a control shaft that is formed in the cylinder block and that extends in the column direction of the cylinder, and is eccentrically provided on the control shaft In the compression ratio variable mechanism of the internal combustion engine comprising the eccentric cam and the control link that links the eccentric cam and the lower link,
An actuator comprising: reciprocating means mechanically linked to rotation of the control shaft for variably controlling the compression ratio of the internal combustion engine; and rotational driving force transmitting means for transmitting the rotational driving force from the rotational driving means to the reciprocating means; A variable compression ratio mechanism for an internal combustion engine, comprising: a detecting means provided in the actuator and detecting a movement amount of the actuator when the control shaft is rotated.   2. A compression ratio variable mechanism for an internal combustion engine according to claim 1, wherein the detection means is a rotation speed sensor for detecting the rotation speed of the rotation drive means.   3. The compression ratio variable mechanism for an internal combustion engine according to claim 2, wherein the rotation speed sensor is a drive Hall IC that controls the rotation of the rotation drive means.   2. The compression ratio variable mechanism for an internal combustion engine according to claim 1, wherein the detecting means is a rotational speed sensor for detecting the rotational speed of the rotational driving force transmitting means.   2. The compression ratio variable mechanism for an internal combustion engine according to claim 1, wherein the detecting means is a linear sensor for detecting a moving distance of the reciprocating means.

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