JP2009036174A - Fuel pump drive of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel pump drive device reducing load to a camshaft and sufficiently exerting ability of a fuel pump driven by an internal combustion engine. <P>SOLUTION: A middle sprocket part 6 having two sprockets is attached to a chain case and a crank sprocket 7 fixed to a crankshaft 5 and a sprocket of the middle sprocket part 6 are connected with a first timing chain 8a and the other sprocket of the middle sprocket part 6 and a cam sprocket 3a fixed to a camshaft for driving intake valve are connected with a second timing chain 8b. The middle sprocket part 6 is rotated at a higher rotation speed than the camshaft and a pump driving shaft of the fuel pump 9 is connected to the middle sprocket part 6 to rotate and drive the pump driving shaft. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel pump drive device for an internal combustion engine that drives a fuel pump that supplies high-pressure fuel to an injector using the power of the internal combustion engine.

  For example, in a cylinder injection internal combustion engine, a high-pressure fuel pump that supplies high-pressure fuel to an injector that injects fuel into a combustion chamber is provided. As a driving method of such a fuel pump, conventionally, a driving method in which a driving shaft of a fuel pump is directly connected to a cam shaft is generally used (see, for example, Patent Document 1).

In Patent Document 1, a fuel pump is attached to a pump mounting portion integrally provided opposite to a side portion of a cylinder head and a side portion of a cam cap, and a journal bearing portion of the cylinder head is pivotally supported by a cam cap. By directly connecting the drive shaft of the fuel pump to the rear end portion of the cam shaft of the valve operating mechanism, the fuel pump is directly driven by the cam shaft.
Japanese Patent Laid-Open No. 11-324846

  However, in the case of the conventional system in which the fuel pump is driven directly connected to the camshaft, the rotational input range of the pump drive shaft of the fuel pump is limited by the principle that the rotation ratio of the camshaft to the crankshaft is 1/2. There was a problem that the capacity of the fuel pump could not be fully utilized. For this reason, conventionally, a large-sized pump having more than necessary capacity for securing the necessary fuel pressure is used while leaving a surplus.

  As for the camshaft, the load applied to the direct camshaft is large, so if the strength of the camshaft for direct coupling is to be higher than that of other camshafts, the materials and processing methods cannot be shared with other camshafts. On the other hand, if you try to share the materials and processing methods of the camshaft for direct connection and other camshafts, other camshafts other than the camshaft for direct connection become excessive quality, and in any case, they were high-cost parts. . Furthermore, in addition to the design quality of the cam parts themselves, there are many problems such as the fixing position and fixing method of the fuel pump as a measure for reducing the load on the cam shaft.

  The present invention has been made paying attention to the above-mentioned problems, and provides a fuel pump drive device for an internal combustion engine that can fully draw out the performance of the fuel pump and can reduce the load on the camshaft. For the purpose.

  For this reason, the fuel pump drive device for an internal combustion engine according to the present invention is provided with an intermediate sprocket portion having two sprockets, and the crank sprocket fixed to the crankshaft and one of the intermediate sprocket portions are connected by a first timing chain. The other sprocket of the intermediate sprocket part and the cam sprocket fixed to the camshaft driving the intake / exhaust valve are connected by a second timing chain, and the intermediate sprocket part is rotated at a higher rotational speed than the camshaft. The pump drive shaft of a fuel pump that supplies high-pressure fuel to the injector is connected to the intermediate sprocket portion to rotate the pump drive shaft.

  According to the present invention, since the number of teeth of the sprocket of the intermediate sprocket portion can be set freely, the pump drive shaft can be driven with the optimum rotation for maximizing the performance of the fuel pump. Further, since the camshaft is released from the fuel pump drive load and the setting of the direct coupling cam is not required, the design specifications, materials, and processing method of the cam parts are made uniform, and the cost can be reduced.

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

  FIG. 1 is a schematic external view of a main part of a first embodiment of a fuel pump driving apparatus for an internal combustion engine according to the present invention, which is an example applied to a V-type 6-cylinder internal combustion engine. FIG. 2 is a cross-sectional view of the connecting portion between the fuel pump and the intermediate sprocket, and FIG. 3 is an exploded perspective view of the connecting portion between the fuel pump and the intermediate sprocket. In FIG. 1, the cylinder head portion is not shown.

  In FIG. 1, the V-type internal combustion engine 1 has first and second cylinder heads mounted on a cylinder block 2 (not shown), and each of the first and second cylinder heads for driving an intake valve and an exhaust valve, respectively. Two camshafts are provided. The camshaft for driving the intake valve and the camshaft for driving the exhaust valve of each cylinder head are interlocked by connecting cam sprockets 3a, 3a, 3b, and 3b to the cam chains 4 and 4, respectively. Each cam shaft is pivotally supported by a cam cap on a journal bearing portion of the cylinder head. Each intake valve driving camshaft has two cam sprockets, one of which is connected to cam chains 4 and 4 and the other of the sprockets is connected to a second timing chain 8b described later.

  An intermediate sprocket portion 6 is disposed above the crankshaft 5, and this intermediate sprocket portion 6 is placed on the rear case 15a portion of the chain case 15 corresponding to the V bank position between the two cylinder heads as shown in FIG. It is installed. As shown in FIG. 3, the intermediate sprocket portion 6 has two sprockets 6a and 6b, and the front sprocket 6a is connected to the crankshaft 5 by a first timing chain 8a and connected to the rear sprocket 6a. 6b is connected to the other cam sprockets 3a, 3a of the intake valve driving cam shafts on both sides by the second timing chain 8b having the same pitch as the first timing chain 8a. Thereby, the rotation of the crankshaft 5 is decelerated to 1/2 through the first and second timing chains 8a and 8b and transmitted to the camshaft for driving the intake valve. It is transmitted to the valve drive camshaft.

  The intermediate sprocket portion 6 is connected to a high-pressure fuel pump 9, and the connection structure of this embodiment will be described with reference to FIGS.

  2 and 3, the intermediate sprocket portion 6 is attached to a sprocket shaft 12 provided with a bush 11, and the sprocket shaft 12 is fastened to the rear case 15a side of the chain case 15 by a sprocket bolt 14 with a washer 13 interposed. . As a result, the intermediate sprocket portion 6 is pivotally supported in the chain case 15 via the sprocket shaft 12. An engagement groove 17 is formed at the front end of the intermediate sprocket portion 6 for engaging with a first coupling member 16A for coupling the intermediate sprocket portion of the Oldham coupling 16 as a connecting member. 17 is engaged with the protrusion 16a of the first coupling member 16A to couple the intermediate sprocket portion 6 to the first coupling member 16A. The second coupling member 16B that couples the pump drive shaft 9A of the Oldham coupling 16 is coupled to the pump drive shaft 9A of the fuel pump 9 by a nut 18, and the second coupling member 16B is engaged with the engagement of the intermediate sprocket portion 6. An engagement groove 19 is formed at a position shifted by 90 degrees from the joint groove 17. By engaging the engaging groove 19 and the projection 16b of the first coupling member 16A to couple the first and second coupling members 16A and 16B to each other, the intermediate sprocket portion 6 and the pump drive shaft 9A are connected to the Oldham cup. Coupled through the ring 16, the driving force is transmitted to the fuel pump 9. The fuel pump 9 is inserted into the front case 15 b of the chain case 15 from the front side of the internal combustion engine 1 and fastened by a bolt 20.

  The first coupling member 16A is formed with a communication hole 21 as a lubricating oil supply oil passage through which the lubricating oil in the chain case 15 can be introduced from the intermediate sprocket part coupling side to the pump drive shaft coupling side. Through this communication hole 21, the lubricating oil in the chain case 15 can be introduced into the Oldham coupling 16 portion. At this time, the fuel pump 9 and the chain case 15 are sealed with an O-ring 22 to prevent leakage of lubricating oil.

  FIG. 4 shows a schematic diagram of driving force transmission from the crankshaft to the camshaft according to the present embodiment.

  The rotation of the crankshaft 5 is transmitted to the intermediate sprocket part 6 by the first timing chain 8a, and the rotation of the intermediate sprocket part 6 is connected to each intake valve drive cam via the second timing chain 8b having the same pitch as the first timing chain 8a. The rotation of the camshafts 3A and 3A is transmitted to the exhaust valve driving camshafts 3B and 3B via the cam chains 4 and 4, respectively.

  In the configuration of this embodiment, the diameter DX of each of the sprockets 6a and 6b of the intermediate sprocket portion 6 is equal to the crank sprocket diameter D1 determined by the gear ratio (1/2) of the crankshaft 5 and the camshaft 3 and the cam sprocket diameter. Any setting can be made without affecting D2. In other words, the number of sprocket teeth of the intermediate sprocket part 6 can be arbitrarily set without affecting the gear ratio between the crankshaft 5 and the camshaft 3A, and the pump of the fuel pump 9 coupled to the intermediate sprocket part 6 Since the rotational speed of the drive shaft 9A can be set higher than the rotational speed of the cam shaft, the rotational speed of the pump drive shaft 9A can be set optimally to maximize the performance of the fuel pump 9.

  On the other hand, in the conventional camshaft direct connection configuration, as shown in FIG. 5, the rotation of the crankshaft 5 is transmitted to the intake valve driving camshafts 3A and 3A by the first timing chain 8, and each camshaft The rotations of 3A and 3A are transmitted to the exhaust valve driving camshafts 3B and 3B via the cam chains 4 and 4, respectively. In this case, it is necessary to decelerate the rotation of the crankshaft 5 by half and transmit it to the camshaft 3A. In the configuration in which the fuel pump is driven by the camshaft, the fuel pump speed is the gear ratio between the crankshaft and the camshaft. Therefore, the drive of the fuel pump is restricted and the capacity of the fuel pump 9 cannot be maximized. In the figure, D3 is the diameter of the cam sprocket of the exhaust valve driving camshaft.

  Further, if the configuration is such that the fuel pump 9 is connected to the intermediate sprocket 6 from the front side of the internal combustion engine 1 as in the present embodiment, the detachability of the fuel pump 9 is improved, and the auxiliary equipment around the front of the current internal combustion engine 1 and There is an advantage that the design of the component structure including the auxiliary belt layout can be easily changed as it is.

  Further, by providing the communication hole 21 in the first coupling member 16A of the Oldham coupling 16, the lubricating oil in the chain case 15 can be sufficiently supplied to the coupling mechanism along each component.

  Next, a second embodiment of the present invention will be described.

  FIG. 6 is a schematic external view of the main part of the second embodiment of the present invention, FIG. 7 is a sectional view of the connecting portion between the fuel pump and the intermediate sprocket, and FIG. 8 is an exploded perspective view of the connecting portion between the fuel pump and the intermediate sprocket. In addition, the same code | symbol is attached | subjected to the same element as 1st Embodiment, and description is abbreviate | omitted.

  In the present embodiment, as shown in FIG. 6, the fuel pump 9 is arranged between the V banks of the V-type internal combustion engine 1 and connected to the intermediate sprocket portion 6 from the rear side of the internal combustion engine 1.

  A connection structure between the intermediate sprocket portion 6 and the fuel pump 9 in the second embodiment will be described with reference to FIGS.

  7 and 8, the rear case 15a of the chain case 15 is sandwiched between the intermediate sprocket portion 6 and the sprocket shaft 12 provided with the bush 11, and the intermediate sprocket portion 6 is connected to the sprocket shaft 14 by a sprocket bolt 14 with a washer 13 interposed. 12 to fasten. Thus, the sprocket shaft 12 is rotatably supported by the rear case 15a via the bush 11, and the intermediate sprocket portion 6 is rotatably supported by the rear case 15a with the sprocket shaft 12 as a shaft portion.

  An engaging groove 12a for engaging with the first coupling member 16A of the Oldham coupling 16 is formed at the rear end of the sprocket shaft 12, and the protrusion of the first coupling member 16A is formed in the engaging groove 12a. The intermediate sprocket portion 6 is coupled to the first coupling member 16A via the sprocket shaft 12 by engaging the 16a.

  An engagement groove 19 is formed in the second coupling member 16B of the Oldham coupling 16 coupled to the pump drive shaft 9A by the nut 18 at a position shifted by 90 degrees from the engagement groove 12a of the sprocket shaft 12. The engaging groove 19 and the protrusion 16b of the first coupling member 16A are engaged to couple the first and second coupling members 16A and 16B to each other. As a result, the intermediate sprocket portion 6 and the pump drive shaft 9 </ b> A are coupled via the sprocket shaft 12 and the Oldham coupling 16, and the driving force is transmitted to the fuel pump 9. The fuel pump 9 is attached to the rear case 15a of the chain case 15 from the rear side of the internal combustion engine 1 by a bolt 33 through an adapter 32 fixed by a bolt 31. The chain case 15 is sealed between the adapter 32 and the fuel pump 9 by O-rings 34 and 22 that prevent leakage of lubricating oil.

  The rear case 15a of the chain case 15 is formed with an oil hole 35 as an oil passage for introducing lubricating oil to the bush 11 portion sliding from the inside of the chain case 15 and from the storage space of the Oldham coupling 16 An oil hole 36 is formed as a lubricating oil return oil passage for returning the lubricating oil into the chain case 15.

  The second embodiment is also similar to the first embodiment, and the number of sprocket teeth of the intermediate sprocket portion 6 can be arbitrarily set without affecting the gear ratio between the crankshaft 5 and the camshaft 3A. Since the number of rotations of the pump drive shaft 9A of the fuel pump 9 coupled to the sprocket unit 6 can be arbitrarily set, the number of rotations of the pump drive shaft 9A can be set optimally to maximize the performance of the fuel pump 9. It becomes.

  Further, if the fuel pump 9 is arranged in the V bank space of the internal combustion engine 1 as in the present embodiment, the compact layout of the internal combustion engine 1 can be achieved by effectively utilizing the V bank space. In the case of a horizontal internal combustion engine, the merit in the layout is further increased depending on the in-vehicle method of the internal combustion engine 1.

  Further, since the oil holes 35 and 36 are formed in the rear case 15a of the chain case 15, sufficient lubrication oil can be supplied to the sliding portions of the sprocket shaft 12 and the bush 11 that are pivotally supported by the rear case 15a. The lubricating oil thus collected can be collected into the chain case 15.

  In the first and second embodiments described above, the two sprockets 6a and 6b of the intermediate sprocket 6 have the same number of teeth. However, as shown in FIG. 9 as the third embodiment of the present invention, the teeth of the sprockets 6a and 6b are used. It is good also as a structure from which a number differs. The number of teeth of the sprocket 6b (diameter D2-1) connected to the camshaft 3A side by the second timing chain 8b is set smaller than the sprocket 6a (diameter DX) connected to the crankshaft 5 side by the first timing chain 8a. To do. Thus, by transmitting the rotation of the crankshaft 5 to the camshaft 3A while decelerating it to the camshaft 3A, the diameter D2-2 of the cam sprocket 3a of the intake valve driving camshaft 3A can be made smaller than before, so that the cam sprocket 3a The internal combustion engine 1 can be made compact.

  Further, as a fourth embodiment of the present invention, for example, an electric control gear is interposed as a speed change means between the intermediate sprocket 6 and the pump drive shaft 9a, and the rotation of the pump drive shaft 9A is performed in a low engine speed range. It is desirable to increase the speed and decelerate in the high engine speed range.

  In such a configuration, the rotational speed of the intermediate sprocket 6 is used as a reference, as shown in FIG. 10, and the speed of the fuel pump is increased in the low engine speed range as shown by the dotted line in the figure by the speed change operation by the electric control gear. The speed of the fuel pump is reduced in the high engine speed range. As a result, the rotational speed region R surrounded by the conventional pump rotational speed characteristic indicated by the thick solid line and the pump rotational speed control characteristic of the present embodiment indicated by the dotted line can be used, and the fuel pump is always controlled to the optimum operating state. It becomes possible, and it becomes possible to draw out the capability of a fuel pump further, and the freedom degree of a layout increases by size reduction of a fuel pump, and it leads also to the internal combustion engine 1 compactization.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic external view of a main portion of a fuel pump drive device for an internal combustion engine according to a first embodiment of the present invention; Sectional drawing of connecting part of fuel pump and intermediate sprocket part of first embodiment The disassembled perspective view of the connecting portion between the fuel pump and the intermediate sprocket of the first embodiment Driving force transmission schematic diagram from the crankshaft to the camshaft of the first embodiment Schematic diagram of driving force transmission from conventional crankshaft to camshaft Main part outline drawing of 2nd Embodiment of this invention Sectional view of the connecting part of the fuel pump and the intermediate sprocket part of the second embodiment Exploded perspective view of connecting portion of fuel pump and intermediate sprocket of second embodiment Driving force transmission schematic diagram from the crankshaft to the camshaft of the third embodiment of the present invention Relationship diagram between engine speed and pump speed showing an example of fuel pump speed control of the fourth embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3A, 3B Cam shaft 3a, 3b Cam sprocket 4 Cam chain 5 Crank shaft 6 Intermediate sprocket part 6a, 6b Sprocket 7 Crank sprocket 8a First timing chain 8b Second timing chain 9 Fuel pump 9A Pump drive shaft 12 Sprocket shaft 15 Chain case 16 Oldham coupling 21 Communication hole 35, 36 Oil hole

Claims (7)

  An intermediate sprocket portion having two sprockets is provided, a crank sprocket fixed to the crankshaft and one sprocket of the intermediate sprocket portion are connected by a first timing chain, and the other sprocket of the intermediate sprocket portion and an intake / exhaust valve are connected A cam sprocket fixed to the camshaft to be driven is connected by a second timing chain, and the intermediate sprocket portion is configured to rotate at a higher rotational speed than the camshaft, and the pump drive shaft of the fuel pump that supplies high pressure fuel to the injector A fuel pump drive device for an internal combustion engine, characterized in that the pump drive shaft is driven to rotate by connecting to the intermediate sprocket portion.   The fuel pump drive device for an internal combustion engine according to claim 1, wherein the pump drive shaft is connected to the intermediate sprocket portion from the front side of the internal combustion engine.   The internal combustion engine is a V-type internal combustion engine, and the fuel pump is disposed between the V banks of the V-type internal combustion engine and connects the pump drive shaft to the intermediate sprocket portion from the rear side of the V-type internal combustion engine; The fuel pump drive apparatus for an internal combustion engine according to claim 1, wherein   The connecting member that connects the intermediate sprocket part and the pump drive shaft has a lubricating oil supply oil passage through which the lubricating oil in the chain case can be introduced from the intermediate sprocket part connecting side of the connecting member to the pump driving shaft connecting side. The fuel pump drive device for an internal combustion engine according to any one of claims 1 to 3, wherein the fuel pump drive device is formed.   A structure in which the shaft portion of the intermediate sprocket portion is rotatably supported on a chain case, and the pump drive shaft of the fuel pump attached to the pump attachment portion outside the chain case and the shaft portion are connected via a connecting member. And a lubricating oil introduction oil passage through which the lubricating oil can be introduced into the chain case from the inside of the chain case to the sliding portion between the shaft portion and the chain case, and from the storage space for the connecting member to the inside of the chain case. The fuel pump drive device for an internal combustion engine according to any one of claims 1 to 4, wherein a lubricating oil return oil passage for returning the lubricating oil is formed.   The fuel pump driving device for an internal combustion engine according to any one of claims 1 to 5, wherein the intermediate sprocket portion has a configuration in which the number of teeth of the two sprockets is different from each other.   A speed change means is interposed between the pump drive shaft and the intermediate sprocket portion, and the speed of the pump drive shaft is increased by the speed change means in a low engine speed range, and a high engine speed range. Then, the fuel pump drive device for the internal combustion engine according to any one of claims 1 to 6, wherein the fuel pump drive device is decelerated.

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