Engine cylinder head structure

Abstract

The present invention provides an engine cylinder head structure that solves as many of the following problems as possible by further designing a fuel accumulator and its supporting structure, etc.: "omitting or shortening a high-pressure-resistant fuel piping," "simplifying or omitting a support frame for a fuel accumulator or / and a fuel injection device," and "reducing the number of components." The present invention provides an engine cylinder head structure that solves as many of the following problems as possible: "omitting or shortening a high-pressure-resistant fuel piping," "simplifying or omitting a support frame for a fuel accumulator or / and a fuel injection device," and "reducing the number of components." The present invention provides an engine cylinder head structure, wherein a support frame (3) for mounting a fuel accumulator (1) on a cylinder head (12) is arranged beside a fuel injection device (2) or between adjacent fuel injection devices (2). The fuel accumulator (1) has a joint (1B) for engaging with the fuel injection device (2), and the support frame (3) has a loading portion (3C) for loading and mounting the fuel accumulator (1); a mounting leg (3A) extending from the loading portion (3C) for mounting the fuel accumulator on the cylinder head (12); and an alignment leg (3B) extending from the loading portion (3C) for positioning the fuel accumulator relative to the cylinder head (12).

Description

Technical Field

[0001] The present invention relates to a structure around a cylinder head of an engine having a fuel accumulator, such as an industrial diesel engine or an automobile engine, that is, an engine cylinder head structure. Background Art

[0002] Typically, engines using a fuel accumulator (such as a common rail system) use a fuel pressure pump to accumulate high-pressure fuel in the fuel accumulator, and high-pressure-resistant fuel piping is laid from the fuel accumulator to the fuel injection devices (injectors) arranged in the cylinders. Patent Documents 1 and 2 disclose known technologies for this purpose.

[0003] It can be seen that the above-mentioned prior art has the following problems shown in A to C: A. A high-pressure-resistant fuel piping is provided, so the fuel piping will cause pressure loss; B. Each fuel injection device requires a fuel piping, so the number of components increases; C. Both the fuel accumulator and the fuel injection device require supporting components, which increases the number of components.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 08-061133

[0007] Patent Document 2: Japanese Patent Application Laid-Open No. 2015-169094 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] To solve the above-mentioned problems A to C, the following technical issues (1) to (3) should be considered: (1) omitting or shortening the high-pressure fuel piping as much as possible; (2) simplifying or omitting the support frame of the fuel accumulator and / or the fuel injection device; (3) reducing the number of parts.

[0010] The object of the present invention is to provide an engine cylinder head structure that solves as many of the above-mentioned problems (1) to (3) as possible by further designing the fuel accumulator and its supporting structure.

[0011] Means used to solve problems

[0012] The engine cylinder head structure of the present invention is characterized in that:

[0013] A support bracket for mounting the fuel accumulator on the cylinder head is arranged beside the fuel injection device or between adjacent fuel injection devices, and the fuel accumulator has a joint portion for engaging with the fuel injection device.

[0014] The support frame includes: a loading portion for loading and mounting the fuel accumulator; a mounting leg extending from the loading portion for mounting to the cylinder head; and an alignment leg extending from the loading portion for positioning relative to the cylinder head.

[0015] The second and other aspects of the present invention are described in the claims.

[0016] Effects of the Invention

[0017] According to the present invention, since the fuel accumulator is directly connected to the fuel injection device, the high-pressure fuel piping required in the prior art is not required, the number of parts can be reduced and the cost can be lowered, and the problem of pressure loss in the fuel piping can be solved.

[0018] Because the support bracket, which carries and supports the fuel accumulator, can be mounted to the cylinder head while being positioned by the alignment legs, mounting the support bracket to the cylinder head with the fuel accumulator assembled allows the fuel injection device mounted on the cylinder head to also be engaged with the fuel accumulator. Furthermore, by mounting the support bracket to the cylinder head with the fuel accumulator already assembled, the fuel injection device can be mounted at a predetermined location on the cylinder head.

[0019] Furthermore, since the position of the fuel injection device is fixed by directly joining the fuel injection device and the fuel accumulator, a dedicated support member for supporting the fuel injection device can be omitted.

[0020] As a result, by further designing the fuel accumulator and its supporting structure, etc., an engine cylinder head structure is provided that solves as many of the above-mentioned problems (1) to (3) as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the right side view of an industrial diesel engine.

[0022] Figure 2 This is a top view of an industrial diesel engine.

[0023] Figure 3 This is a rear view of an industrial diesel engine.

[0024] Figure 4 is a partially cutaway rear view showing a key portion of the support structure of the common rail system.

[0025] Figure 5 It is a right side view, partially cut away, showing a key portion of the support structure of the common rail system.

[0026] Figure 6 This is a partially cutaway front view showing a key portion of the support structure of the common rail system as viewed obliquely from above.

[0027] Figure 7 is a diagram showing a support frame, Figure 7 (A) is the right side view, Figure 7 (B) is the main view.

[0028] Figure 8 is a diagram showing a support frame, Figure 8 (A) is a top view, Figure 8 (B) is along Figure 8 The main view observed in the direction of the Z arrow in (A).

[0029] Figure 9 is a diagram showing a common rail system. Figure 9 (A) is the right side, Figure 9 (B) is a top view.

[0030] Figure 10 (A) is the main view of the common rail system. Figure 10 (B) is to indicate the tilt angle of the injector relative to the cylinder head. Figure 2 Cross-sectional view of the key part after ZZ line cutting.

[0031] Figure 11 This is a schematic diagram showing that the mounting surface of the common rail system and the support bracket and the injector engaging surface of the support bracket are on the same plane. DETAILED DESCRIPTION

[0032] An embodiment of the engine cylinder head structure of the present invention will be described below with reference to the accompanying drawings, using an industrial diesel engine (hereinafter referred to as the "engine") mounted on an agricultural tractor or construction equipment. The engine's cooling fan side is defined as the front, the flywheel side is defined as the rear, the exhaust manifold side (exhaust side) is defined as the left, and the intake manifold side (intake side) is defined as the right.

[0033] Figures 1 to 3 The figure shows an inline three-cylinder common rail industrial diesel engine. In this engine E, a cylinder head 12 is assembled to a cylinder block 11, and a cylinder head cover 13 is assembled to the cylinder head 12. A transmission case 14 and an oil pan 15 are assembled in front of and below the cylinder block 11, respectively.

[0034] A transmission belt 16, an engine cooling fan 17, and the like are arranged at the front of the engine E, while a flywheel 18, a flywheel housing bracket 19, and the like are arranged at the rear of the engine E. An alternator 20, an exhaust manifold 21, a battery starter 22, and the like are arranged at the left of the engine E, while an intake manifold 23, an oil filter 24, a fuel supply pump 25, and the like are arranged at the right of the engine E. A common rail system (an example of a fuel accumulator) 1, a water passage 26, and the like are arranged at the top of the engine E.

[0035] Next, the structure around the cylinder head 12 and the cylinder head cover 13, that is, the engine cylinder head structure will be described. Figures 1 to 3 and Figures 4 to 6 As shown, the common rail system 1 is installed in a front-to-back orientation above the cylinder head 12 and to the right of the cylinder head cover 13. The common rail system 1 is directly connected to three injectors (an example of a fuel injection device) 2 mounted on the cylinder head 12 and is mounted to the cylinder head 12 via two support brackets 3.

[0036] like Figures 1 to 3 and Figures 4 to 6 As shown, the three injectors 2, 2, 2 are arranged along the in-line direction of the cylinder, i.e., the front-to-back direction, and have an injection axis P inclined in the up-down direction so as to become higher as it goes to the right and rear (the more it goes to the right and the more it goes to the rear), and are loaded on the cylinder head 12 in an inserted state in a state of standing up from the upper surface of the cylinder head 12, i.e., the cylinder head upper surface 12A.

[0037] like Figure 10 (B) Figure 11 As shown, the injection axes P are parallel to each other and are set to be inclined at an angle θ relative to the vertical direction with respect to the upper surface 12A of the cylinder head. The angle θ is set to 10 to 30 degrees (10°≤θ≤30°), preferably 20 degrees. The injector 2 is set to a state where high-pressure fuel is injected into the auxiliary chamber 8 provided in the combustion chamber (not shown). In addition, as shown in FIG. Figure 5 and Figure 10 As shown in FIG. 1B , an annular sleeve 7 is provided on the cylinder head 12 by press-fitting. The annular sleeve 7 is used to determine the installation height position of the injector 2 relative to the cylinder head 12 .

[0038] like Figures 1 to 6 、 Figure 9 、 Figure 10 As shown, the common rail system 1 comprises a rail body 1A, which is tubular and elongated in the inline direction (front-to-back direction) of the cylinders; three joints 1B formed in the rail body 1A for connecting with the injectors 2; and two supported portions 1C disposed between the joints 1B. A supply portion 1D and an overflow outlet 1E are formed at the front and rear ends of the rail body 1A, respectively. The supply portion 1D is connected to a supply pipe 27 connected to a fuel supply pump 25. A boss (not shown) for mounting a pressure sensor (not shown) by screwing or other means may be formed in the center of the longitudinal direction of the rail body 1A, and a pressure regulating valve (not shown) may be provided at the rear end of the rail body 1A. The common rail system 1 is mounted to the cylinder head top surface 12A via two support brackets 3, 3 arranged in a front-to-rear arrangement.

[0039] like Figures 4 to 8As shown, the support bracket 3 is formed into a downward-pointing U-shaped member (metal member) having a loading portion 3C, a mounting leg 3A, and an alignment leg 3B. The loading portion 3C loads and mounts the supported portion 1C of the common rail system 1. The mounting leg 3A extends from the loading portion 3C and is used for mounting the support bracket 1C toward the cylinder head 12. The alignment leg 3B extends from the loading portion 3C and is used for positioning the support bracket 3 relative to the cylinder head 12. Furthermore, the shape of the support bracket 3 may be other than the U-shape, such as a "mouth" shape or a substantially "π" shape.

[0040] The loading portion 3C has a through-hole 3e and a small hole 3d formed therein. The through-hole 3e is formed in a vertical direction and is used to screw the supported portion 1C loaded on the upper surface 3c from below via a support bolt 6. The small hole 3d is formed to receive a pin 28 for positioning or preventing rotation. The mounting leg 3A has an insertion hole 3a formed therein and is used to bolt the mounting leg 3A to the cylinder head upper surface 12A from above. The alignment leg 3B has a positioning hole 3b formed therein and is used to receive a positioning pin (an example of a positioning member) 4 that determines the relative position of the support frame 3 and the cylinder head 12. A horizontal seating surface 3f is formed at the rear end of the loading portion 3C, where the opening of the through-hole 3a is located.

[0041] A nut portion 30 is formed on the upper portion of the cylinder head 12, opening into the cylinder head upper surface 12A. A second positioning hole 12n is formed that is externally engaged with the positioning pin 4. The nut portion 30 is threadedly engaged with a bolt 29 that passes through the mounting leg 3A. With the alignment leg 3B positioned relative to the cylinder head 12 by the positioning pin 4, the mounting leg 3A is screwed to the cylinder head upper surface 12A with the bolt 29, thereby securing each support bracket 3.

[0042] like Figure 5 、 Figure 8 (A) Figure 8 As shown in (B), the mounting surface 5 and the joint surface 1b are located in the same plane. The mounting surface 5 is formed by the mounting surface between the common rail system 1 and the loading portion 3C, that is, the bottom surface 1c of the supported portion 1C or the upper surface 3c of the loading portion 3C. The joint surface 1b is formed by the joint surface between the injector 2 adjacent to the support frame 3 having the mounting surface 5 (bottom surface 1c, upper surface 3c) and the common rail system 1, that is, the lower surface of the joint 1B.

[0043] Specifically, if Figure 9 and Figure 11As shown, the first joint surface 1b1 (first from the front) and the first bottom surface 1c1 (first from the front) are located in the same plane S, and the second joint surface 1b2 (second from the front) and the second bottom surface 1c2 (second from the front) are located in the same plane T. There is no bottom surface 1c that is located in the same plane U as the third joint surface 1b3 (third from the front) (last). Furthermore, the four surfaces—the first joint surface 1b1, the first bottom surface 1c1, the second joint surface 1b2, the second bottom surface 1c2, and the third joint surface 1b3 (third from the front) (last)—are parallel to each other.

[0044] like Figure 5 、 Figure 10 、 Figure 11 As shown, the supported portion 1C is formed with a nut portion 1n for tightening the support bolt 6 and an upward hole 1f for fitting the pin 28. In addition, the joint portion 1B is formed with a mounting hole 1g for fitting the upper portion of the injector 2.

[0045] That is, a mounting foot 3A is provided on the rear side (an example of one end side) of the loading portion 3C, and an alignment foot 3B is provided on the front side (an example of the other end side) of the loading portion 3C, and the support frame 3 is provided in a "U"-shaped member that opens downward when viewed from a direction intersecting the in-line direction of the cylinder (a direction from slightly rearward on the right side toward slightly forward on the left side).

[0046] In the assembled state where the common rail system 1 is mounted on the cylinder head 12 using the support brackets 3, 3, the three injectors 2 inserted and mounted on the cylinder head 12 are directly connected to the common rail system 1, and the injectors 2 can be prevented from falling off upward. Figures 1 to 3 、 Figure 5 Reference numeral 31 denotes a blow-by gas return pipe connecting the top of the cylinder head cover 13 and the intake manifold 23 for returning the blow-by gas.

[0047] like Figures 8 to 11 As shown, the axis Y of the alignment leg 3B of the support frame 3 (the axis of the positioning hole 3b) is set to an angle parallel to the angle θ of the injection axis P (the angle relative to the vertical direction of the cylinder head upper surface 12A). In other words, the positioning hole 3b and the upward hole 1f have an axis Y that is orthogonal to the joint surface 1b. In addition, the axis of the joint 1B (the axis of the mounting hole 1g) is the same as the injection axis P, and the axis Q of the nut portion 1n and the through hole 3e, as well as the axis Y of the positioning hole 3b and the upward hole 1f, are all set to be parallel to the injection axis P. In addition, the direction of the axis (not shown) of the mounting leg 3A (through hole 3a, bolt 29) is perpendicular to the cylinder head upper surface 12A.

[0048] Because the first joint surface 1b1 and the first bottom surface 1c1 can be formed in a single machining operation, the second joint surface 1b2 and the second bottom surface 1c2 can be formed in a single machining operation, and the third joint surface 1b3 can be formed in a single machining operation, a total of three machining operations can be performed. This has the following advantages: Compared to a situation where the two bottom surfaces 1c and the three joint surfaces 1b are located in different planes and a total of five machining operations are required, the process can be completed with a smaller number of machining operations. Furthermore, setting the two bottom surfaces 1c and the three joint surfaces 1b to the same inclination angle is preferred because it improves machining accuracy and reduces machining costs. Furthermore, if "parallel surfaces" are used instead of "being located in the same plane," the following advantages can be achieved: compared to a situation where the surfaces are not parallel to each other, the angle setting of the machining tool can be completed with a single operation.

[0049] Reference Figures 4 to 6 The common rail system 1 is assembled on the cylinder head 12 as follows. First, the common rail system 1 and the two support brackets 3, 3 are assembled using the support bolts 6 and the pins 28. Next, the injectors 2 corresponding to the mounting holes 1g of the joints 1B are inserted into the ASSY assembly (pre-assembly) of the common rail system 1 with the two support brackets 3, 3. With the support brackets 3 and the cylinder head 12 positioned using the positioning pins 4, the support brackets 3, 3 are fastened to the cylinder head upper surface 12A using the two bolts 29, 29, thereby completing the assembly of the common rail system 1.

[0050] With the common rail system 1 assembled to the cylinder head 12, the common rail system 1 is joined (connected) to the injectors 2, and the injectors 2 are held in their installed state to prevent them from falling off the cylinder head 12. The common rail system 1 and the support brackets 3 are positioned using pins 28, and the support brackets 3 and the cylinder head 12 are positioned using positioning pins 4. The support brackets 3 are then attached to the cylinder head 12 using bolts 29, 29. This allows the three joints 1B and the three injectors 2 to be joined (connected) without difficulty.

[0051] Alternatively, the following assembly procedure may be employed: two support brackets 3 and three injectors 2 are assembled to the common rail system 1 in advance, and the common rail system 1 having the two support brackets 3 and three injectors 2 is assembled to the cylinder head 12 via the two support brackets 3 .

[0052] The engine cylinder head structure according to the embodiment of the present invention can achieve the following effects 1 to 8:

[0053] 1. Because the common rail system 1 and the injectors 2 are directly connected, pressure loss can be reduced compared to connecting them with piping, thereby improving fuel consumption and reducing costs. Furthermore, since the bracket for the injectors 2 can be eliminated, costs can be reduced and component reliability can be improved.

[0054] 2. It has the following advantages: Since the common rail 1 is mounted on the cylinder head 12 by the support bracket 3, the vibration frequencies of the two can be set to be the same, which can reduce costs and improve durability and reliability.

[0055] 3. Since an overflow outlet portion 1E (overflow function) is provided on the common rail system 1 itself, compared with the method of providing an overflow pipe on each injector, the assembly and disassembly can be simplified, which is beneficial to cost reduction.

[0056] 4. Since the bolts for fixing the common rail system 1 and the support bracket 3 are tightened from below the loading portion 3C, the support bracket 3 does not need to be located at a position higher than the common rail system 1, and compactness in terms of height can be achieved.

[0057] 5. It has the following advantages: Since the support bracket 3 is formed in a downward "U" shape in which the mounting feet 3A and the alignment feet 3B extend downward from the respective ends of the loading portion 3C, interference between adjacent components and the support bolts 6 can be avoided, and the support bolts 6 can be loaded and unloaded even in the state of being assembled to the cylinder head 12, and the maintainability is excellent. As long as the loading and unloading or rotation operation of the support bolts 6 can be achieved, the shape of the support bracket 3 can be a shape other than the "U" shape (for example, a "square" shape, a "U" or "square" shape with a horizontal depression).

[0058] 6. Since the mounting surface 5 (bottom surface 1c) of the common rail system 1 with respect to the support bracket 3 and the joint surface 1b of the common rail system 1 with respect to the injector 2 are located in the same planes S and T, the processing cost can be reduced and the processing time can be shortened.

[0059] 7. Since a positioning pin 4 for positioning the support bracket 3 and the cylinder head 12 is provided, enabling the common rail system 1 and the injector 2 ASSY to be assembled (pre-assembled) and then assembled to the cylinder head 12, the ease of assembly and cost reduction can be achieved.

[0060] 8. Since a sleeve 7 for determining the mounting height of the injector 2 with respect to the cylinder head 12 is provided, the accuracy of the joint portion (connection portion) between the injector 2 and the common rail system 1 can be improved, which is beneficial to improving durability. In addition, if the sleeve 7 is pressed into the cylinder head 12, rotation of the sleeve can be prevented, which is preferable.

[0061] 〔Other Embodiments〕

[0062] For example, in an in-line two-cylinder diesel engine, it can be a structure in which a support bracket is arranged outside each injector to provide a common rail system. In this case, a structure of "the support bracket 3 is arranged beside the fuel injection device 2" is formed.

[0063] Description of Reference Numerals

[0064] 1Fuel accumulator (common rail system)

[0065] 1b joint surface

[0066] 2Fuel injection device (injector)

[0067] 3 support frame

[0068] 3A installation foot

[0069] 3B Align the feet

[0070] 3C loading unit

[0071] 3a through hole

[0072] 3b positioning hole

[0073] 3e through-hole

[0074] 4 Positioning components

[0075] 5. Mounting surface

[0076] 12 cylinder heads

[0077] Y axis

Claims

1. An engine cylinder head structure, wherein: A support bracket for mounting the fuel accumulator on the cylinder head is arranged beside the fuel injection device or between adjacent fuel injection devices, and the fuel accumulator has a joint portion for engaging with the fuel injection device. The support frame has: a loading unit for loading and installing the fuel accumulator; a mounting foot extending from the loading portion and used for mounting on the cylinder head; an alignment foot extending from the loading portion for positioning relative to the cylinder head, The loading portion is formed with a through hole for fixing the fuel accumulator loaded on the loading portion with a bolt from below. The mounting foot is provided with a through hole for fixing the mounting foot to the cylinder head from above with a bolt. The mounting foot is provided on one end side of the loading portion, and the alignment foot is provided on the other end side of the loading portion. The support frame is provided in a "コ" shape with a downward opening. A seat surface on which a bolt head of the bolt is seated is formed at an upper end of the support bracket at a position offset toward the one end side from an upper surface of the mounting portion in contact with the fuel accumulator.

2. The engine cylinder head structure according to claim 1, wherein: A positioning hole is formed on the alignment foot, and the positioning hole is used to embed a positioning member for determining the relative position between the support bracket and the cylinder head.

3. The engine cylinder head structure according to claim 2, wherein: A mounting surface between the fuel accumulator and the mounting portion and a joint surface between the fuel injection device and the fuel accumulator adjacent to the support frame having the mounting surface are located on the same plane.

4. The engine cylinder head structure according to claim 3, wherein: The positioning hole has an axis that is perpendicular to the joint surface.

5. The engine cylinder head structure according to any one of claims 1 to 4, wherein: The support frame is provided in a U-shape that opens downward when viewed from a direction intersecting the cylinder in-line direction.

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