JP2006161651A - Variable stroke characteristic engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrict enlargement of the whole length of an engine in the axial direction of a control shaft due to an actuator, which drives the control shaft, to the minimum in a variable stroke characteristic engine. <P>SOLUTION: In the engine, of which piston stroke characteristic is changed by rotating the control shaft 25 with the actuator 31 to vertically move a control link 28 to change motion constraining condition of a lower link 18 supported by a crank shaft 17, since the control link 28 adjacent to, at least, the actuator 31 is displaced in a direction of separating a connection part to the control shaft 25 from the actuator 31 in relation to a connection part to a lower link 18, enlargement of dimension of the engine E in the axial direction of the control shaft 25 can be restricted to the minimum by transferring the actuator 31 toward a central part by the displaced distance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a variable stroke characteristic engine that changes the position of a top dead center or a bottom dead center of a piston by rotating a control shaft with a drive device.

The lower link supported swingably on the pin journal of the crankshaft is connected to the piston via the upper link and to the control shaft via the control link, and the motion of the lower link is restricted by rotating the control shaft with an actuator. A stroke characteristic variable engine that changes the stroke characteristics including the positions of the top dead center and the bottom dead center of the piston by changing the conditions is known from Patent Document 1 below.
Japanese Patent Application Laid-Open No. 2003-322036

  By the way, since the control shaft arranged in parallel with the crankshaft drives a plurality of control links provided for each cylinder, the total length is substantially equal to the total length of the engine block. Therefore, when the actuator is directly connected to the shaft end of the control shaft, the actuator protrudes from the end of the engine block, and there is a problem that the engine is enlarged in the axial direction of the control shaft.

  The present invention has been made in view of the above-described circumstances, and in a variable stroke characteristic engine, it is an object to minimize the increase in the overall length of the engine in the axial direction of the control shaft by a drive device that drives the control shaft. And

  In order to achieve the above object, according to the invention described in claim 1, a crankshaft in which the main journal is rotatably supported by the engine block, and a control shaft in which the main journal is rotatably supported by the engine block. A lower link swingably supported by the pin journal of the crankshaft, an upper link connecting the lower link to the piston, a control link connecting the lower link or upper link to the pin journal of the control shaft, and a control shaft In the variable stroke characteristic engine having a drive device that is arranged on the axis of the drive shaft and rotationally drives the control shaft, at least the control link adjacent to the drive device is connected to the lower link or the connection to the upper link. Connecting part for cement roll shaft, the stroke characteristic variable engine wherein it is displaced in the direction away from the drive unit in the axial direction of the control shaft is proposed.

  According to the second aspect of the present invention, in addition to the configuration of the first aspect, the drive device is disposed between the adjacent cylinders, and the pair of control links adjacent to both sides in the axial direction of the drive device includes the lower link. There is proposed a variable stroke characteristic engine characterized in that the connecting portion for the control shaft is displaced in the direction away from the drive device in the axial direction of the control shaft with respect to the connecting portion for the link or the upper link.

  In addition, the actuator 31 of an Example respond | corresponds to the drive device of this invention.

  According to the configuration of the first aspect, the lower link is swingably supported by the pin journal of the crankshaft, the lower link is connected to the piston via the upper link, and the lower link or the upper link is connected via the control link. Since it is connected to the pin journal of the control shaft, the stroke characteristics of the piston can be changed by changing the motion restraint condition of the lower link by rotating the control shaft around the main journal and moving the control link up and down.

  At least the control link adjacent to the drive device is provided at the end of the control shaft because the connection portion to the control shaft is displaced away from the drive device with respect to the connection portion to the lower link or the upper link. By moving the drive unit closer to the center of the control shaft by the amount of displacement, and securing a space for placing the drive unit in the middle of the control shaft, the drive increases the size of the engine in the axial direction of the control shaft. Can be minimized.

  According to the configuration of the second aspect, the pair of control links located on both sides of the drive device disposed between the adjacent cylinders has a connection portion for the control shaft separated from the drive device with respect to the connection portion for the lower link or the upper link. Since the drive device is disposed in a space secured between adjacent cylinders inside the engine block, the drive device prevents the engine from being enlarged in the axial direction of the control shaft. Can do.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 8 show an embodiment of the present invention. FIG. 1 is a front view of a variable compression ratio engine, FIG. 2 is a longitudinal sectional view (high compression ratio state) of the variable compression ratio engine, and FIG. FIG. 4 is a view taken along line 4-4 in FIG. 2, FIG. 5 is a view taken in the direction of arrow 5 in FIG. 2, and FIG. 7 is a longitudinal sectional view (low compression ratio state) of the variable compression ratio engine, and FIG. 8 is a hydraulic circuit diagram of an actuator control system.

  As shown in FIGS. 1 to 5, a variable compression ratio engine E, which is an example of a variable stroke characteristic engine capable of changing the position of the top dead center or the bottom dead center of a piston, includes a cylinder block 11, a crankcase 12, and a cylinder head. The engine block 14 is coupled to the cylinder head 13, the head cover 15 is coupled to the upper part of the cylinder head 13, and the oil pan 16 is coupled to the lower part of the crankcase 12. A main journal 17a of the crankshaft 17 is rotatably supported on the split surfaces of the cylinder block 11 and the crankcase 12, and an intermediate portion of a substantially triangular lower link 18 is swingable on a pin journal 17b eccentric from the main journal 17a. It is supported by.

  A piston 21 is slidably fitted to a cylinder sleeve 20 provided in the cylinder block 11, and the upper end of an upper link 22 (connecting rod) is pivotally supported by the piston 21 via a piston pin 23. The lower end of 22 is pivotally supported on one end of the lower link 18 via the first pin 24. A main journal 25a of a crank-shaped control shaft 25 is pivoted on a lower surface of the crankcase 12 that is offset laterally from the position of the crankshaft 17 by a cap 27 fastened to the crankcase 12 by bolts 26 and 26. Be supported. The control link 28 includes a main body portion 28a and a cap portion 28b fastened to the lower end of the main body portion 28a with bolts 29, 29. The upper end of the main body portion 28a is connected to the other end portion of the lower link 18 via the second pin 30. The pin journal 25b of the control shaft 25 is pivotally supported between the lower end of the main body portion 28a and the cap portion 28b. The control shaft 25 is swung in a range of a predetermined angle by a hydraulic control actuator 31 provided at one end thereof.

  An intake port 32 and an exhaust port 33 are opened in a combustion chamber 13 a formed on the lower surface of the cylinder head 13, and an intake valve 34 that opens and closes the intake port 32 and an exhaust valve 35 that opens and closes the exhaust port 33. Is provided. The intake valve 34 is driven to open / close by an intake camshaft 36 via an intake rocker arm 37, and the exhaust valve 35 is driven to open / close by an exhaust camshaft 38 via an exhaust rocker arm 39.

  As is apparent from FIGS. 1 and 6, a chain cover 41 is detachably fixed to one end surface of the engine block 14 including the cylinder block 11, the crankcase 12, and the cylinder head 13 with a plurality of bolts 42. A timing chain 43 disposed in a space between the engine block 14 and the chain cover 41 is connected to the drive sprocket 44 provided at the shaft end of the crankshaft 17 and the shaft ends of the intake camshaft 36 and the exhaust camshaft 38, respectively. It is wound around the provided driven sprockets 45 and 46.

  The end surface of the crankcase 12 is exposed at a portion where the lower end on the intake side of the chain cover 41 is cut out in an arc shape, and the actuator 31 is fitted into that portion and fixed to the crankcase 12 with a plurality of bolts 47. Is done. A valve block 48 for controlling the operation of the actuator 31 is fixed to a side surface on the intake side of the crankcase 12 with a plurality of bolts 49.

  As shown in FIG. 8, the actuator 31 is provided with fan-shaped oil chambers 53, 53 that swingably accommodate a pair of vanes 52, 52 extending on both sides of the rotating shaft 51, and an oil tank 54 and an oil chamber 53. , 53, an oil pump 56 driven by a motor 55, a check valve 57, an accumulator 58, and a direction switching valve 59 are arranged. Accordingly, when the direction switching valve 59 is switched to the left, the vanes 52 and 52 are pushed by the hydraulic pressure generated by the oil pump 56, the rotating shaft 51 rotates counterclockwise, and conversely the direction switching valve 59 is switched to the right. When the vanes 52 and 52 are pushed by the hydraulic pressure generated by the oil pump 56 and the rotating shaft 51 rotates in the clockwise direction, the phase of the control shaft 25 connected to the rotating shaft 51 changes.

  As apparent from FIGS. 4 and 5, of the four control links 28 connected to the four pin journals 25 b of the control shaft 25, one control disposed closest to the actuator 31. The link 28 is different in shape from the other three control links 28. That is, the other three control links 28... Extend linearly in a direction perpendicular to the axis of the control shaft 25, whereas one control link 28 closest to the actuator 31 is curved in an S shape. Thus, the connection portion with the control link 28 is displaced in the direction away from the actuator 31 by the distance α with respect to the connection portion with the lower link 18.

  As apparent from FIG. 6, the end of the control link 28 on the control shaft 25 side is offset by a distance α in the right direction in the figure, so that the mounting seat formed on the end face of the crankcase 12 via the step 12b. The position of 12a can be offset rightward by the distance α, and the protrusion amount β of the actuator 31 attached to the mounting seat 12a from the end face of the crankcase 12 becomes smaller.

  Next, the operation of the first embodiment of the present invention having the above configuration will be described.

  The actuator 31 is driven according to the operating state of the engine E, and the control shaft 25 connected to the actuator 31 rotates to an arbitrary position between the position shown in FIG. 2 and the position shown in FIG. In the position shown in FIG. 2, the pin journal 25 b is positioned below the main journal 25 a of the control shaft 25, so that the control link 28 is pulled down and the lower link 18 is clockwise around the pin journal 17 b of the crankshaft 17. And the upper link 22 is pushed up to raise the position of the piston 21, so that the engine E enters a high compression ratio state.

  On the contrary, in the position shown in FIG. 7, the pin journal 25 b is positioned above the main journal 25 a of the control shaft 25, so that the control link 28 is pushed up and the lower link 18 is centered on the pin journal 17 b of the crankshaft 17. When the upper link 22 is pulled down and the position of the piston 21 is lowered, the engine E is in a low compression ratio state.

  As described above, the control link 28 moves up and down by the swinging of the control shaft 25, the motion constraint condition of the lower link 18 changes, and the stroke characteristics including the top dead center position of the piston 21 change. The compression ratio is arbitrarily controlled.

  Since the control arm 28 adjacent to the actuator 31 has an asymmetric shape in the axial direction of the control shaft 25, a space for moving the actuator 31 toward the central portion of the control shaft 25 can be secured. The amount of protrusion β of the actuator 31 (see FIG. 6) can be minimized and the engine E can be made compact.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the end of the control link 28 is fitted to the bifurcated end of the lower link 18 and pivotally supported by the second pin 30, but in the second embodiment, the lower link 18 A forked end of the control link 28 is fitted to the thinned end and pivotally supported by the second pin 30. In the second embodiment, three of the four control links 28... Have a symmetrical shape in the axial direction of the control shaft 25, but one control link 28 closest to the actuator 31 is the control shaft 25. The control link 28 has a space on the side surface of the control link 28 facing the actuator 31. That is, the axial direction center of the end of the one control link 28 on the control shaft 25 side is the axial direction on the side farther from the actuator 31 in the end of the control link 28 on the lower link 18 side. Offset to coincide with the center of.

  Then, by using this space, the position of the actuator 31 is moved toward the center of the control shaft 25, so that the amount of projection of the actuator 31 from the end face of the crankcase 12 is reduced, and the same effect as the first embodiment. Can be achieved.

  Next, a third embodiment of the present invention will be described with reference to FIG.

  In the first and second embodiments, the actuator 31 is arranged at one end of the control shaft 25. However, in the third embodiment, the control shaft is equally divided into two at the center, and the control shafts 25 and 25 are opposed to each other. A common actuator 31 is arranged in each part. The actuator 31 is arranged at the position where the central main journal 25a of the five main journals 25a... Of the control shaft 25 of the first and second embodiments is located. In order to secure the arrangement space, Two control links 28 and 28 adjacent to both sides of the actuator 31 have the same asymmetric shape as that of the second embodiment.

  According to the third embodiment, since the actuator 31 can be housed in the engine block 14, the actuator 31 is prevented from protruding from the end face of the engine block 14 and the engine E can be made more compact. Can do.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, although the variable compression ratio engine has been described in the embodiment, one or both of the compression ratio and the displacement of the engine can be changed by changing the size of each part with the same structure. The present invention can be applied to these variable stroke characteristic engines.

  In the embodiment, the hydraulic actuator 31 is directly connected to the control shaft 25, but an electric motor may be used instead of the hydraulic actuator 31, and a gear or belt is provided between the control shaft 25 and the actuator 31. A transmission mechanism such as a chain may be interposed.

  Further, the control shaft 25 is not limited to the swing axis, and may be a rotation axis whose rotation angle exceeds 360 °.

  In the embodiment, the control link 28 is connected to the lower link 18, but the present invention can also be applied to a variable stroke characteristic engine in which the control link 28 is connected to the upper link 22.

Front view of variable compression ratio engine Vertical section of variable compression ratio engine (high compression ratio state) 3-3 arrow view of FIG. 4-4 arrow view of FIG. 5 direction arrow view of FIG. Sectional view taken along line 6-6 in FIG. Vertical section of variable compression ratio engine (low compression ratio state) Hydraulic circuit diagram of actuator control system The figure corresponding to said 4 according to 2nd Example of this invention. The figure corresponding to said 4 based on 3rd Example of this invention.

Explanation of symbols

14 Engine block 17 Crankshaft 17a Main journal 17b Pin journal 18 Lower link 21 Piston 22 Upper link 25 Control shaft 25a Main journal 25b Pin journal 28 Control link 31 Actuator (drive device)

Claims (2)

A crankshaft (17) having a main journal (17a) rotatably supported by an engine block (14);
A control shaft (25) in which the main journal (25a) is rotatably supported by the engine block (14);
A lower link (18) swingably supported by a pin journal (17b) of the crankshaft (17);
An upper link (22) connecting the lower link (18) to the piston (21);
A control link (28) connecting the lower link (18) or the upper link (22) to the pin journal (25b) of the control shaft (25);
A drive device (31) disposed on the axis of the control shaft (25) to rotationally drive the control shaft (25);
In the variable stroke characteristic engine with
At least the control link (28) adjacent to the drive unit (31) is connected to the lower link (18) or the upper link (22), whereas the connection to the control shaft (25) is connected to the control shaft (25). A variable stroke characteristic engine characterized by being displaced in a direction away from the drive device (31) in the axial direction. A drive unit (31) is arranged between adjacent cylinders, and a pair of control links (28) adjacent to both sides in the axial direction of the drive unit (31) are connected to the lower link (18) or the upper link (22). On the other hand, the connecting portion for the control shaft (25) is displaced in a direction away from the drive device (31) in the axial direction of the control shaft (25). Variable characteristics engine.

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