JP4591199B2 - Variable compression ratio engine - Google Patents

Description

  The present invention relates to a variable compression ratio engine that changes a compression ratio by relatively displacing a cylinder block with respect to a crankcase, and more particularly to a mounting structure for auxiliary machinery.

There has been proposed an engine in which the compression ratio is variable by changing the combustion chamber volume by relatively displacing the cylinder block with respect to the crankcase (see, for example, Patent Document 1).
Japanese Patent No. 3224816 JP 2003-206871 A Japanese Patent Laid-Open No. 11-200949

  In the above-described variable compression ratio engine, accessories such as an alternator that are driven using the rotational torque of the crankshaft have to be attached to the wall surface of the crankcase. This is because the rotational torque of the crankshaft is transmitted to the auxiliaries via the belt, so that when the auxiliaries are mounted on the wall surface of the cylinder block, the distance between the crankshaft and the auxiliaries is changed as the compression ratio is changed. This is because there is a possibility that the auxiliary machine cannot be operated normally due to the change.

  By the way, when attaching auxiliary machinery to the wall surface of the crankcase, in order to ensure sufficient mounting rigidity, measures such as increasing the wall thickness of the crankcase wall or providing many reinforcing ribs are necessary. There is a possibility that the weight of the engine will increase and the manufacturing cost will increase.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to increase the weight of the engine or manufacture the variable compression ratio engine that changes the compression ratio by relatively displacing the cylinder block with respect to the crankcase. The purpose is to increase the attachment rigidity of the auxiliary machinery while suppressing an increase in cost.

  In order to solve the above-described problems, the present invention provides a variable compression ratio engine having a displacement mechanism for displacing a cylinder block with respect to a crankcase, and a support member for supporting an auxiliary device is fixed to the housing of the displacement mechanism. It is characterized by doing.

  Since the displacement mechanism of the variable compression ratio engine needs to be subjected to the high combustion pressure of the engine and to displace the cylinder block against the combustion pressure, the housing supporting the displacement mechanism has high strength and / or rigidity. Yes.

  A support member for supporting the auxiliary machine is fixed to such a housing, and preferably the housing and the support member are integrally formed, thereby suppressing an increase in the thickness of the crankcase wall surface and an increase in the reinforcing rib. It becomes possible to increase the attachment rigidity of the auxiliary machine with respect to.

In addition, when the support member is fixed to the housing of the displacement mechanism, the displacement mechanism is easily subjected to heat generated by the auxiliary machine in addition to the heat of the engine, so that the temperature of the displacement mechanism is low, such as after a cold start. Thus, the displacement mechanism can be warmed up early. If the displacement mechanism is warmed up early, it is possible to increase the control accuracy of the compression ratio after cold start and to reduce the driving force required to drive the displacement mechanism.

  When the support member is formed separately from the housing of the displacement mechanism, the bolt for fixing the housing to the crankcase and the bolt for fixing the support member to the housing may be shared. Good.

  If the support member is formed separately from the housing, the heat of the auxiliary machine is less likely to be transferred to the displacement mechanism compared to the case where the support member and the housing are integrally formed, but if the bolt is shared, the auxiliary machine is connected via the bolt. Heat is easily transferred to the displacement mechanism.

  In the present invention, when it is necessary to fix a plurality of positions of the support member to the crankcase, a part of the plurality of fixing positions is fixed to the housing of the displacement mechanism, and the remaining fixing positions are fixed to the wall surface of the crankcase. You may do it.

  Auxiliary mounting locations are subject to restrictions such as the positional relationship with other auxiliary machinery and the vehicle mountability of the engine, but some of the fixed locations described above are fixed to the housing of the displacement mechanism and the remaining fixed locations Can be fixed to the crankcase wall surface, it is possible to mount the auxiliary equipment within the limits of the above-mentioned restrictions while minimizing the increase in the wall thickness of the crankcase wall and the increase in the reinforcing ribs. It becomes.

  Examples of the support member in the present invention include a bracket and a boss.

  As an auxiliary machine in this invention, a generator (alternator), a hydraulic pump, the compressor of an air conditioner, etc. can be illustrated.

  Examples of the displacement mechanism in the present invention include a mechanism that changes the position of the cylinder block in the cylinder axis direction by the rotation of the eccentric shaft.

  According to the present invention, in a variable compression ratio engine provided with a displacement mechanism that relatively displaces a cylinder block with respect to a crankcase, it is possible to increase the attachment rigidity of auxiliary equipment while suppressing an increase in the weight of the engine and an increase in manufacturing cost. It becomes possible. Furthermore, according to the present invention, the heat of the auxiliary machine is easily transmitted to the displacement mechanism, so that the displacement mechanism can be warmed up early, such as during cold weather.

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

  First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of an engine 1 to which the present invention is applied. The engine 1 includes a cylinder block 2 and a crankcase 3.

  The cylinder block 2 is slidably attached to the crankcase 3 in the cylinder axial direction. Displacement mechanisms 4 for displacing the cylinder block 2 are provided at portions where the cylinder block 2 and the crankcase 3 overlap on both side surfaces of the engine 1 in the cylinder arrangement direction.

  FIG. 2 is a diagram showing the configuration of the displacement mechanism 4. A plurality of raised portions are formed at the lower portions on both sides of the cylinder block 2, and a cam housing hole 6 is formed in each raised portion. These cam housing holes 6 are formed in parallel to the cylinder arrangement direction and on the same axis.

  The crankcase 3 is formed with a standing wall portion 7a so as to be positioned between the plurality of raised portions in which the above-described cam housing holes 6 are formed. A semicircular recess is formed on the surface of each standing wall 7a facing the outside of the crankcase. A cap 7 b having a semicircular recess is fixed to each standing wall 7 a by a bolt 8. When the standing wall portion 7a and the cap 7b are fixed, a circular bearing housing hole 9 is formed by both concave portions. The inner diameter of the bearing accommodation hole 9 is the same as that of the cam accommodation hole 6.

  When the cylinder block 2 and the crankcase 3 configured as described above are connected, communication holes in which the cam storage holes 6 and the bearing storage holes 9 are alternately arranged are formed on both side surfaces of the cylinder block 2 and the crankcase 3. Is done. The eccentric cam shafts 5 are respectively inserted into these communication holes.

  Each eccentric cam shaft 5 includes a single shaft portion 5a, a plurality of cam portions 5b, and a movable bearing portion 5c. The cam portion 5b has a regular circular cam profile and is eccentrically fixed to the shaft portion 5a. The movable bearing portion 5c has the same shape as the cam portion 5b and is rotatably attached to the shaft portion 5a.

  The cam portions 5b and the movable bearing portions 5c are alternately arranged so that the cam portions 5b are accommodated in the cam accommodating holes 6 and the movable bearing portions 5c are accommodated in the bearing accommodating holes 9.

  An actuator 50 is provided at one end of the eccentric cam shaft 5 thus configured. The actuator 50 includes worm wheels 51a and 51b fixed to one end of the shaft portion 5a of each eccentric cam shaft 5, worms 52a and 52b meshing with the worm wheels 51a and 51b, and a motor 53 that rotationally drives the worms 52a and 52b. It has. The motor 53 is fixed to the cylinder block 2.

  The centers of the worm wheels 51a and 51b are offset from the center axis of the shaft portion 5a and coincide with the center of the cam portion 5b. Further, the spiral grooves of the worms 52a and 52b are formed in opposite directions, and the two eccentric cam shafts 5 are rotated in the opposite directions by the rotation of the motor 53.

  Here, the basic operation of the displacement mechanism 4 will be described with reference to FIG. 3, a, b, and c represent the center of the shaft portion 5a, the center of the cam portion 5b, and the center of the movable bearing portion 5c, respectively.

  FIG. 3A shows a state where the compression ratio is the highest, in other words, a state where the cylinder block 2 is most displaced toward the bottom dead center side. In this case, the centers b and c of all the cam portions 5b and the movable bearing portions 5c are located on the same axis, and the outer peripheral surfaces of the cam portions 5b and the movable bearing portions 5c coincide in the axial direction. Correspondingly, the centers of the cam storage hole 6 and the bearing storage hole 9 also coincide with each other.

  When the compression ratio is lowered from the state of FIG. 3A, the motor 53 is controlled so that the two eccentric cam shafts 5 rotate in the direction of the arrow in the figure. FIG. 3B shows a state in which the eccentric cam shaft 5 has been rotated approximately 45 ° from the state of FIG. In this case, the center b of the cam portion 5b is offset toward the top dead center side with respect to the center c of the movable bearing portion 5c, and accordingly the outer peripheral surface of the cam portion 5b is also top dead with respect to the outer peripheral surface of the movable bearing portion 5c. Offset to the point side.

When the cam portion 5b is offset toward the top dead center side with respect to the movable bearing portion 5c, the cam housing hole 6 is also offset toward the top dead center side with respect to the bearing housing hole 9, so that the cylinder block 2 is connected to the crankcase 3. Is displaced toward the top dead center. When the cylinder block 2 is displaced toward the top dead center side with respect to the crankcase 3, the combustion chamber volume is increased, and the compression ratio of the internal combustion engine 1 is reduced.

  When the motor 53 further rotates the two eccentric cam shafts 5 in the direction of the arrow in the figure, the offset amount between the cam portion 5b and the movable bearing portion 5c further increases, and the compression ratio is further reduced accordingly. FIG. 3C shows a state in which the eccentric cam shaft 5 is rotated by 90 ° from the state of FIG.

  At this time, the center a of the shaft portion 5a, the center b of the cam portion 5b, and the center c of the movable bearing portion 5c are aligned in the cylinder axial direction, and the offset amount between the cam portion 5b and the movable bearing portion 5c is maximized. That is, when the eccentric cam shaft 5 is rotated 90 ° from the state of FIG. 3A, the displacement amount to the top dead center side of the cylinder block 2 becomes the maximum. As a result, the compression ratio of the internal combustion engine 1 is the lowest.

  When the compression ratio is increased from the state shown in FIGS. 3B and 3C, the motor 53 rotates in the reverse direction to rotate the two eccentric cam shafts 5 in the direction opposite to the arrow direction in FIG. You can do it.

  Thus, according to the displacement mechanism 4, the cylinder block 2 can be displaced in the cylinder axial direction, and the compression ratio of the internal combustion engine 1 can be freely changed accordingly.

  By the way, in a conventional engine, an auxiliary machine driven by a crankshaft, such as an alternator, a hydraulic pump, or an air conditioner compressor, may be attached to the cylinder block. If the machine is attached to the cylinder block 2, the auxiliary machine may not operate normally.

  Power transmission from the crankshaft to the auxiliary machine is made by connecting pulleys attached to each of the auxiliary machine and the crankshaft with a belt. When the auxiliary machine is attached to the cylinder block 2 in the variable compression ratio engine, As the compression ratio changes, the distance between the crankshaft pulley (crank pulley) and the auxiliary pulley changes.

  If the distance between the crank pulley and the auxiliary pulley becomes excessively short, the belt tension becomes excessively low, and the rotational torque of the crank pulley may not be transmitted to the auxiliary pulley. On the other hand, if the distance between the crank pulley and the auxiliary pulley becomes excessively long, the belt tension becomes excessively high, which may cause rotation failure of the crank pulley and the auxiliary pulley.

  Therefore, the auxiliary machine of the variable compression ratio engine 1 is preferably attached to the crankcase 3. However, in general, the strength and rigidity of the crankcase wall surface tends to be lower than that of the cylinder block wall surface. Therefore, in order to ensure the necessary and sufficient mounting rigidity and strength, the thickness of the crankcase wall surface is increased, or It is necessary to take measures such as providing many reinforcing ribs. If the wall thickness of the crankcase wall is increased or a reinforcing rib is added, problems such as an increase in the weight of the engine and an increase in manufacturing costs may occur.

  On the other hand, in this embodiment, the accessory is attached to the housing of the displacement mechanism 4. In the example shown in FIGS. 1 and 2, the standing wall portion 7 a and the cap 7 b fastened to each other by the bolt 8 correspond to the housing of the displacement mechanism 4.

  The cap 7b and the upright wall portion 7a receive the combustion pressure of the engine 1 through the eccentric cam shaft 5, and the torque of the motor 50 that rotates the eccentric cam shaft 5 (displaces the cylinder block 2) against the combustion pressure. Therefore, the rigidity and strength are designed to be higher than those of other parts of the crankcase 3.

Therefore, if the accessory is attached to the cap 7b, the attachment rigidity and strength of the accessory can be increased without taking measures such as increasing the wall thickness of the crankcase wall or adding a reinforcing rib.

  Here, referring back to FIG. 1, a specific method of attaching the auxiliary machine will be described. In the example shown in FIG. 1, the bracket 11 for supporting the alternator 10 is fixed to the cap 7 b of the displacement mechanism 4. At this time, the cap 7b and the bracket 11 may be integrally molded in advance, but the bracket 11 separate from the cap 7b may be fixed to the cap 7b with a plurality of bolts.

  When the bracket 11 is fixed to the cap 7b with a plurality of bolts, as many bolts as possible among the plurality of bolts may be shared with the cap mounting bolts 8 and the remaining bolts may be dedicated bolts 12. preferable.

  When the cap mounting bolt 8 also serves as a fixing bolt for the bracket 11, in addition to the advantages of simplifying the structure of the crankcase 3 and reducing the number of parts, the displacement mechanism 4 is warmed up using the heat generated by the alternator 10. The excellent effect that it can be made can be acquired.

  The displacement mechanism 4 is provided at a joint portion between the cylinder block 2 and the crankcase 3, but since the joint portion is separated from the combustion chamber, the heat of the combustion chamber is not easily transmitted to the displacement mechanism 4. If the heat in the combustion chamber is difficult to be transmitted to the displacement mechanism 4, the displacement mechanism 4 will not easily rise to an appropriate temperature when the engine 1 is cold-started, causing problems such as increased friction and reduced compression ratio control accuracy. there's a possibility that.

  On the other hand, when the cap mounting bolt 8 also serves as a fixing bolt for the bracket 11, the heat generated by the alternator 10 is easily transmitted to the cap 7 b via the bolt 8. As a result, when the engine 1 is cold-started, the displacement mechanism 4 can easily rise in temperature to an appropriate temperature, so that an increase in friction and a decrease in control accuracy of the compression ratio can be suppressed.

  In addition, when attaching a plurality of auxiliary machines to the crankcase 3, it is necessary to consider the size of the pulley diameter of each auxiliary machine, the rotation balance of the belt, the on-vehicle performance of the engine 1, and the like. The mounting position is restricted. Under such restrictions, it may be difficult to attach all auxiliary brackets to the cap 7b.

  Therefore, in the example of FIG. 1, with respect to the bracket 14 of the hydraulic pump 13 and the bracket 16 of the air conditioner compressor 15, a part of the plurality of fixing portions of the brackets 14 and 16 are fixed to the cap 7b, and the remaining fixing portions are fixed. It was fixed to the wall surface of the crankcase 3.

  Specifically, one part of the bracket 14 of the hydraulic pump 13 is fixed to the cap 7b by a bolt 8 for mounting the cap, and the other part of the bracket 14 is fixed to the wall surface of the crankcase 3 by a dedicated bolt not shown. Is done. Further, one part of the bracket 16 of the air conditioner compressor 15 is fixed to the cap 7 b by the cap mounting bolt 8, and the other part of the bracket 16 is fixed to the wall surface of the crankcase 3 by the dedicated bolt 17.

  According to such an attachment method, it is possible to increase the attachment rigidity and attachment strength of the auxiliary machine while minimizing the number of reinforcements on the wall surface of the crankcase within the range of various restrictions as described above.

Therefore, according to the variable compression ratio engine of the present embodiment, it is possible to increase the mounting rigidity and mounting strength of the auxiliary machines while suppressing an increase in the weight of the engine 1 and an increase in manufacturing cost, and the displacement mechanism 4.
It becomes possible to improve the warm-up property.

  The alternator 10, the hydraulic pump 13, and the air conditioner compressor 15 described in the present embodiment are examples of the auxiliary machine according to the present invention, and the auxiliary machine according to the present invention is not limited to these. Further, the mounting position of the alternator 10, the hydraulic pump 13, and the air conditioner compressor 15 is not limited to the mounting position shown in FIG. 1, but depends on the shape of the engine 1 and the shape of the engine room in which the engine 1 is mounted. It is changed as appropriate.

It is a figure which shows schematic structure of a variable compression ratio engine. It is a figure which shows the structure of a displacement mechanism. It is a figure which shows operation | movement of a displacement mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Cylinder block 3 ... Crankcase 4 ... Displacement mechanism 7a ... Standing wall part (housing)
7b ··· Cap (housing)
8 ... Bolt 10 ... Alternator (auxiliary machine)
11 .... Bracket (supporting member)
13 .... Hydraulic pump (auxiliary machine)
14 .... Bracket (supporting member)
15 .... Air conditioner compressor (auxiliary)
16 .... Bracket (supporting member)

Claims (3)

In a variable compression ratio engine having a displacement mechanism for displacing a cylinder block with respect to a crankcase,
The displacement mechanism, comprises an eccentric cam shaft, the housings a bearing member for supporting the eccentric cam shaft in contact with the eccentric cam shaft is provided in the crankcase, and
A variable compression ratio engine characterized in that at least a part of a support member for supporting an auxiliary machine driven by a crankshaft is fixed to the housing.   The variable compression ratio engine according to claim 1, wherein the support member is formed integrally with the housing.   2. The variable compression ratio according to claim 1, wherein the support member is formed separately from the housing, and a bolt for fixing the support member to the housing and a bolt for fixing the housing to the crankcase are shared. engine.

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