JP2007113411A - Engine mount bracket fastening structure - Google Patents

Abstract

[PROBLEMS] To secure a sealing property that does not cause oil leakage from a chain cover, regardless of the type of engine and mounting method.
An engine includes a cylinder head 1000 and a cylinder block 2000 as main components. A timing chain cover 4000 for housing the timing chain 3000 is provided on both end faces of the cylinder head 1000 and the cylinder block 2000. The timing chain cover 4000 is provided with an engine mount bracket 5000. A cylinder head 1000, a timing chain cover 4000, and an engine mount bracket 5000, which have a thermal expansion amount larger than the thermal expansion amount of the cylinder block 2000, are fastened together with fastening bolts 5100. The engine mount bracket 5000 is not fastened to the cylinder block 2000 but fastened to the timing chain cover 4000 with fastening bolts 5200.
[Selection] Figure 1

Description

  The present invention relates to a technology for mounting an engine on a vehicle, and more particularly to a fastening structure of an engine mounting bracket.

  In general, a power plant in which an engine and a transmission are integrally assembled is often mounted on a vehicle body using a total of three engine mount brackets. As such an engine mount structure, for example, the engine mount bracket and the water pump case are fastened together with the cylinder block, and the above-mentioned engine mount bracket is inserted from the inside of the timing belt cover through the opening of the cover. There is a structure that protrudes to the outside of the timing belt cover.

  As described above, in the engine of the type in which the camshaft is driven by the timing belt, the above-described engine mount bracket can be attached with the timing belt cover protruding, but the engine of the type in which the camshaft is driven by the chain. In this case, since an oil chamber is formed by the chain cover, a sufficient seal structure is required, and it is not preferable that the engine mount bracket is mounted with the chain cover protruding.

  Therefore, when sufficient sealability is required for the chain cover, it is of course possible to ensure the sealability, but the engine mount bracket does not protrude from the chain cover and the engine mount bracket installation space is secured. In addition, it is necessary to improve the fastening rigidity between the cylinder block and the cylinder head. Japanese Patent Laid-Open No. 6-193460 (Patent Document 1) discloses such an engine mounting structure.

  The engine mounting structure disclosed in this publication is a horizontal V-type DOHC (Double Overhead Camshaft) engine mounting structure in which the first sprocket fixed to the intake camshaft of one bank and the other bank A chain is wound around a second sprocket fixed to the exhaust camshaft and a third sprocket fixed to the crankshaft, a chain cover is provided to cover the chain, and two fastening portions are intake camshafts on the other bank An engine mount bracket located on the outer side of the chain cover below the end is disposed between the banks, and the lower part of the engine mount bracket is fastened together with the block side of the chain cover with respect to the cylinder block, and Engine for cylinder head below intake camshaft Mounting brackets top are those that are head-side and fastened together in the chain cover.

According to this engine mounting structure, since the engine mounting bracket is positioned outside the chain cover, it is possible to ensure the sealing performance of the chain cover whose inside is set in the oil chamber. Furthermore, the engine mount bracket is disposed below the intake camshaft end of the other bank, in other words, the sprocket is not attached to the other bank, and the surplus space with no protrusion is effectively utilized, so that the horizontal mounting V-type A mounting space for the engine mount bracket can be secured in the DOHC engine.
JP-A-6-193460

  However, the engine mounting structure disclosed in the above-mentioned publication is only applicable to a horizontal V-type DOHC engine. Furthermore, according to FIG. 2 of this publication, in addition to the cylinder block 1, the chain cover 26, and the engine mount bracket 37 being fastened together with bolts 38, the Elinda head 3, the chain cover 26, The engine mount bracket 37 is fastened together with bolts 40. That is, the engine mount bracket 37 is fastened to the cylinder block 1 and the cylinder head 3 via the chain cover 26.

  As described above, when the engine mounting bracket has the same fastening structure with the same kind of fastening members (bolts) on the cylinder head and the cylinder block, there are the following problems. When the engine is operated, the temperature on the cylinder head side rises because there is a combustion chamber on the cylinder head side. For this reason, both the cylinder head and cylinder block whose materials are metal thermally expand, but in the case of the same material, the amount of expansion on the cylinder head side that receives more heat is large, even if different materials are the same It is difficult to obtain an expansion amount (thus, a difference occurs in the expansion amount).

  As a result, in the fastening structure disclosed in the above-mentioned publication, for example, when the expansion amount of the cylinder head 3 is large, the mounting bracket 37 is attached to the engine by the extension of the cylinder head 3 with the fastening point by the bolt 38 on the cylinder block 1 side as a fulcrum. Receives outward force. Due to this force, the surface pressure in the vicinity of the mating surfaces of the cylinder block 1, the cylinder head 3, and the chain cover 26 may decrease, and an opening of the seal surface may be recognized. Sealing performance may be reduced due to the opening of the sealing surface, and oil leakage may occur from the chain cover 26.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an engine mount capable of ensuring a sealing property that does not cause oil leakage from the chain cover regardless of the type of engine and the mounting method. It is providing the fastening structure of a bracket.

  A fastening structure according to a first invention is a fastening structure of an engine mount bracket attached to a chain cover of an engine. The engine mount bracket is attached so as to intersect a surface obtained by extending a mating surface between the cylinder head and the cylinder block. A seal member is provided on a joint surface between the chain cover, the cylinder head, and the cylinder block. In this engine, only one of the cylinder head and the cylinder block, the chain cover, and the engine mount bracket are fastened together by a fastening member.

  According to the first aspect of the present invention, the seal member is provided on the joint surface between the chain cover, the cylinder head, and the cylinder block to prevent oil that lubricates the chain from leaking from the chain cover. While the engine is operating, the degree of thermal expansion differs between the cylinder head and the cylinder block, for example, the amount of thermal expansion of the cylinder head closer to the combustion chamber is larger than the amount of thermal expansion of the cylinder block. Further, the engine mount bracket is attached so as to intersect a surface obtained by extending a mating surface between the cylinder head and the cylinder block. For this reason, in the present invention, only one of the cylinder head and the cylinder block, the chain cover, and the engine mount bracket are fastened together by the fastening member. In the conventional fastening structure in which the members of both the cylinder head and the cylinder block, the chain cover, and the engine mount bracket are fastened together with a fastening member, due to the difference in thermal expansion (the fastening member on the cylinder head side and the cylinder block side) A force is generated with a fastening portion by one fastening member (of the fastening member) as a fulcrum, and a force that lowers the surface pressure acts on the joint surface between either the cylinder head or the cylinder block and the chain cover. On the other hand, since the engine mount bracket of the present invention is fastened together with only one member of the cylinder head and the cylinder block, there is no fulcrum and no force for reducing the surface pressure is generated. Since no force for reducing the surface pressure is generated, the sealing member provided on the joint surface is not damaged. As a result, it is possible to provide a fastening structure for an engine mount bracket that can ensure a sealing property that does not cause oil leakage from the chain cover regardless of the type of engine and the mounting method. In addition, the generation mechanism of the force which reduces a surface pressure is not limited to having the fulcrum mentioned above.

  In the fastening structure according to the second invention, in addition to the configuration of the first invention, the member is a member of the cylinder head and the cylinder block that has a larger expansion due to the combustion heat of the engine.

  According to the second aspect of the present invention, the engine mount bracket is a member of only one of the cylinder head and the cylinder block, and is fastened together only with the larger expansion due to the combustion heat. If the cylinder block is fastened to the engine mount bracket due to the expansion of the cylinder head that is more expanded, a force that lowers the surface pressure is generated using the fastening point on the cylinder block side as a fulcrum. In the present invention, since the cylinder block is not fastened to the engine mount bracket, there is no fulcrum and no force for reducing the surface pressure is generated. As a result, it is possible to provide a fastening structure for an engine mount bracket that can ensure a sealing property that does not cause oil leakage from the chain cover regardless of the type of engine and the mounting method.

  In the fastening structure according to the third invention, in addition to the configuration of the first or second invention, when the cylinder head and the cylinder block are made of the same material, the member is a cylinder head.

  According to the third invention, when the cylinder head and the cylinder block are made of the same material, the cylinder head closer to the combustion chamber of the engine has a larger heat reception amount, so that only the cylinder head having a large expansion amount is fastened to the engine mount bracket. The cylinder block and the engine mount bracket are not fastened.

  In the fastening structure according to the fourth invention, in addition to the configuration of any one of the first to third inventions, the seal member is a liquid gasket.

  According to the fourth aspect of the present invention, since no force for reducing the surface pressure is generated, the liquid gasket that is a seal member provided on the joint surface is not damaged.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  An engine having an engine mount bracket fastening structure according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view of a DOHC engine having a VVT (Variable Valve Timing) mechanism, in which a timing chain cover 4000 is removed from a cylinder head 1000 and a cylinder block 2000. FIG. This engine is a DOHC engine having two intake valves and two exhaust valves per cylinder. Note that the present invention is not limited to such an engine, and is an engine having a cylinder head and a cylinder block, and any engine that fastens an engine mount bracket to the engine via a timing chain cover. There is no particular limitation on the type and mounting method.

  The engine has the cylinder head 1000 and the cylinder block 2000 as the main components, and these are made of iron (cast iron), aluminum, magnesium, or an alloy containing them. The cylinder head 1000 and the cylinder block 2000 are fastened with a plurality of bolts via a gasket (not shown). On the cylinder head 1000 side, an intake camshaft 1010 for operating the intake valve and an exhaust camshaft 1020 for operating the exhaust valve are provided. The intake camshaft 1010 is provided with a cam for operating two intake valves provided for each cylinder, and the exhaust camshaft 1020 is provided with a cam for operating two exhaust valves provided for each cylinder. ing.

  Furthermore, a VVT mechanism for adjusting the operation timing of the intake valve is provided on the intake side. This VVT mechanism is controlled by an engine ECU (Electronic Control Unit) to adjust the valve overlap or the like by advancing or retarding the operation timing of the intake valve so that desired engine characteristics can be obtained. I have to.

  Intake camshaft 1010 and exhaust camshaft 1020 are connected to the engine crankshaft on the cylinder block 2000 side by a timing chain 3000. The driving force of the engine is transmitted by the timing chain 3000, and the intake camshaft 1010 and the exhaust camshaft 1020 are rotated. In addition to the timing chain 3000, an oil pump drive chain 3100 for driving the oil pump 3300 is provided. Further, a tensioner 3200 and a chain guide 3400 for applying a desired tension to these chains are provided. Further, the engine is provided with a water pump 3500 that is driven by a belt provided on the crankshaft.

  The engine is provided with a timing chain cover 4000 formed on the side of the cylinder head 1000 and the cylinder block 2000 so as to have a space (also a chain oil chamber) containing the chain. This timing chain cover 4000 is also made of iron (cast iron), aluminum, magnesium, or an alloy containing these. Since the camshaft driven by the timing chain 3000 is on the cylinder head 1000 side and the crankshaft of the driving source is on the cylinder block 2000 side, the timing chain 3000 straddles the cylinder head 1000 and the cylinder block 2000 to each sprocket. Wrapped around. For this reason, the timing chain cover 4000 is provided so as to straddle the cylinder head 1000 and the cylinder block 2000.

  Further, (engine) oil for lubricating the timing chain 3000 is circulated in the space formed by the timing chain cover 4000. Therefore, a liquid gasket is provided as a seal member on the end surface of the timing chain cover 4000 and on the joint surface between the cylinder head 1000 and the cylinder block 2000. With this liquid gasket, oil leakage from the timing chain cover 4000 is avoided.

  Further, the timing chain cover 4000 is provided with an engine mount bracket 5000 for suspending the engine itself on the chassis. The material of the engine mount bracket 5000 is often highly rigid iron (cast iron).

  The engine mount bracket 5000 is fastened to the timing chain cover 4000 and also fastened to the cylinder head 1000. However, the engine mount bracket 5000 is not fastened to the cylinder block 2000. The feature of the present invention is that the engine mount bracket 5000 is fastened only to either the cylinder head 1000 or the cylinder block 2000.

  In other words, the engine mount bracket 5000 is attached so as to intersect the surface obtained by extending the mating surface of the cylinder head 1000 and the cylinder block 2000, but the engine mount bracket 5000 is attached only to either the cylinder head 1000 or the cylinder block 2000. It is not fastened (in this embodiment, it is fastened only to the cylinder head 1000 having a higher degree of thermal expansion as will be described later).

  While the engine is in operation, a mixed gas of fuel and air is combusted in the combustion chamber on the cylinder head 1000 side, and the explosive force generated during the combustion serves as a drive source for the engine. The cylinder head 1000 on the side where the combustion chamber is present receives a larger proportion of heat than the cylinder block 2000. As described above, since the cylinder head 1000 and the cylinder block 2000 are metallic, thermal expansion occurs due to heat reception. For example, when the cylinder head 1000 and the cylinder block 2000 are made of the same material (for example, iron or aluminum), they have the same thermal expansion coefficient (linear expansion coefficient or volume expansion coefficient per unit heat quantity), so that a larger amount of heat can be obtained. The amount of expansion of the cylinder head 1000 to be received (the length and volume extended by heat reception are collectively referred to as the expansion amount) is larger than the expansion amount of the cylinder block 2000. Further, when the cylinder head 1000 is made of aluminum or an aluminum alloy mainly composed of aluminum, and the cylinder block 2000 is made of iron (cast iron), the coefficient of thermal expansion of aluminum is larger than that of iron, and the cylinder head 1000 (aluminum) Since the heat is received more than the cylinder block 2000 (iron), the expansion amount of the cylinder head 1000 is larger than the expansion amount of the cylinder block 2000 as compared with the case of the same material.

  It is theoretically possible to adopt a material having a low expansion coefficient for the cylinder head 1000 having a higher heat reception, and adopting a material having a high expansion coefficient to the cylinder block 2000 having a lower heat reception than the cylinder head 1000 so as to have the same expansion amount. However, in reality, it is realistic to set the same expansion amount in the cylinder head 1000 and the cylinder block 2000 due to difficulty in analyzing the heat receiving path due to the complexity of the shape, deviation from the theoretical formula of the heat receiving amount, and the like. is not. Therefore, in actuality, the thermal expansion amount of the cylinder head 1000 is different from the thermal expansion amount of the cylinder block 2000 regardless of the combination of materials, and in many cases, the thermal expansion amount of the cylinder head 1000 that receives a larger amount of heat. Is big. For this reason, in the present embodiment, the engine mount bracket 5000 is fastened to the cylinder head 1000 having a large thermal expansion amount via the timing chain cover 4000.

  As described above, depending on the shape, material, and heat receiving path of the engine, when the cylinder block 2000 has a larger amount of thermal expansion, the timing chain cover 4000 is attached only to the cylinder block 2000, not the cylinder head 1000. The engine mount bracket 5000 may be fastened.

  Furthermore, although it is described in a confirming manner, the present invention includes the following modifications as long as the effect of achieving sealing performance can be ensured even if the difference in thermal expansion is not clear. This modification has a fastening structure in which the engine mount bracket 5000 is fastened only to either the cylinder head 1000 or the cylinder block 2000 via the timing chain cover 4000.

  Since the expansion amount of the cylinder head 1000 is larger than the expansion amount of the cylinder block 2000, the engine mount bracket 5000 is fastened only to the cylinder head 1000 having a larger thermal expansion amount as described below. . With reference to FIG. 2 and FIG. 3, the effect of the case where it fastens in this way (FIG. 2) is demonstrated using the figure (FIG. 3) which shows the conventional fastening method.

  FIG. 2 is a partial cross-sectional view showing a fastening structure of engine mount bracket 5000 according to the present embodiment. FIG. 3 shows a fastening structure of a conventional engine mount bracket 5001 corresponding to FIG.

  As shown in FIGS. 1 and 2, in the present embodiment, engine mount bracket 5000 passes through timing chain cover 4000 and is fastened to cylinder head 1000 by fastening bolts 5100. However, on the cylinder block 2000 side, the engine mount bracket 5000 is fastened to the timing chain cover 4000 by the fastening bolt 5200 without penetrating the timing chain cover 4000. On the other hand, as shown in FIG. 3 compared with FIG. 2, in the conventional structure, the engine mount bracket 5001 passes through the timing chain cover 4001 and is fastened to the cylinder head 1000 and the cylinder block 2000 by fastening bolts 5101. The

  In such a case, the amount of heat received by the cylinder head 1000 becomes larger than the amount of heat received by the cylinder block 2000 when the engine is operated and the mixed gas is combusted in the combustion chamber. As described above, regardless of the combination of materials, the thermal expansion amount of the cylinder head 1000 and the thermal expansion amount of the cylinder block 2000 are different, and in many cases, the thermal expansion amount of the cylinder head 1000 that receives a larger amount of heat is large.

  Therefore, in the conventional structure shown in FIG. 3, the amount of thermal expansion of the cylinder head 1000 is large, and the engine mount bracket 5000 exerts a clockwise force in FIG. 3 with the vicinity of the fastening point A on the cylinder block 2000 side as a fulcrum. receive. As a result, the surface pressure in the vicinity of the mating surface B of the cylinder head 1000, cylinder block 2000, and timing chain cover 4000 (the pressure at which the timing chain cover 4000 presses the cylinder head 1000 and cylinder block 2000) decreases, and the seal surface in the vicinity of point B. The liquid gasket provided as the seal member may be damaged. If it becomes like this, the oil leakage from the timing chain cover 4000 will occur.

  On the other hand, in the case of the structure in the present embodiment shown in FIG. 2, even if the amount of thermal expansion of the cylinder head 1000 is large, there is no point corresponding to the fulcrum on the cylinder block 2000 side in the vicinity of the fastening point A in FIG. . That is, even if the cylinder head 2000 is deformed larger than the cylinder block 3000 due to the difference in thermal expansion, the cylinder block 2000 and the engine mount bracket 5000 are not fastened. The engine mount bracket 5000 is only fastened to the timing chain cover 4000. The force generated when the cylinder head 2000 is deformed to be larger than the cylinder block 3000 acts on the engine mount bracket 5000, and the force may act on the timing chain cover 4000 via the fastening bolt 5200. Even if the timing chain cover 4000 is deformed as a result, it does not act on the cylinder block 2000. As a result, the surface pressure in the vicinity of the mating surfaces of the cylinder head 1000, the cylinder block 2000, and the timing chain cover 4000 does not drop, the opening of the mating surfaces does not occur, and the liquid gasket provided as the seal member does not break. For this reason, oil leakage from the timing chain cover 4000 does not occur.

  As described above, according to the engine mount bracket fastening structure according to the present embodiment, when the engine mount bracket is attached to the chain cover across the cylinder head and the cylinder block, the engine mount bracket is fastened to the cylinder head. However, the cylinder block is not fastened. For this reason, even if a difference in the amount of thermal expansion occurs, the opening of the seal member at the joint surface between the chain cover, the cylinder head, and the cylinder block does not occur. As a result, it is possible to provide a fastening structure for an engine mount bracket that can ensure a sealing property that does not cause oil leakage from the chain cover regardless of the type of engine and the mounting method.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a perspective view of an engine which has an engine mount bracket fastening structure concerning an embodiment of the invention. It is a fragmentary sectional view of FIG. It is the conventional fastening structure corresponding to FIG.

Explanation of symbols

  1000 cylinder head, 1010 intake camshaft, 1020 exhaust camshaft, 2000 cylinder block, 3000 timing chain, 3100 oil pump drive chain, 3200 tensioner, 3300 oil pump, 3400 chain guide, 3500 water pump, 4000, 4001 timing chain cover, 5000, 5001 Engine mount bracket, 5100, 5101, 5200 Fastening bolt.

Claims (4)

A fastening structure of an engine mount bracket attached to a chain cover of an engine, wherein the engine mount bracket is attached so as to intersect a surface obtained by extending a mating surface of a cylinder head and a cylinder block, and the chain cover and the cylinder head And a sealing member is provided on the joint surface with the cylinder block,
A fastening structure of an engine mount bracket, wherein a member of only one of the cylinder head and the cylinder block, the chain cover, and the engine mount bracket are fastened together by a fastening member.   2. The fastening structure for an engine mount bracket according to claim 1, wherein the member is a member that is larger in expansion due to combustion heat of the engine in the cylinder head and the cylinder block.   The fastening structure for an engine mount bracket according to claim 1 or 2, wherein when the cylinder head and the cylinder block are made of the same material, the member is the cylinder head.   The fastening structure for an engine mount bracket according to claim 1, wherein the seal member is a liquid gasket.

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