Pump housing with pressure relief cut for lobe clearance

Abstract

The present disclosure relates to a fuel pump housing and a fuel pump system incorporating the same. The fuel pump housing includes at least one lifter housing portion configured to receive at least one lifter assembly and a main bore portion fluidly coupled with the at least one lifter housing portion such that the main bore receives a camshaft. The main bore includes an uncut portion and at least one pressure relief cut portion proximate the at least one lifter housing portion. The uncut portion defines a first centerline and the pressure relief cut portion defines a second centerline offset from the first centerline.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 082,598, filed September 24, 2020, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates generally to fuel systems, and more specifically to fuel pumps having guided reciprocating tappet assemblies and methods for guiding the tappet assemblies and assembling the fuel pump. Background Technology

[0004] Various fuel pumps used to supply fuel to internal combustion engines are driven by a camshaft with a cam cam angle, which uses rollers rolling along the cam cam angle to displace a tappet assembly. The reciprocating motion of the tappet assembly generates a fuel flow, which is used by the internal combustion engine to generate power. These types of fuel pumps are often used in common rail fuel system applications that require high fuel pressure. In such fuel pumps, the reciprocating tappet assembly is guided such that the centerline of the roller and the centerline of the camshaft are kept aligned relative to each other. While this configuration achieves high fuel pressure in fuel system applications, there is still room for technological improvement.

[0005] Figure 1 shows a fuel pump housing 100 with tappet guide holes 102, in which tappet assemblies 101 are received. Each tappet assembly 101 includes a tappet spring 104, a lower spring retainer 105, a tappet housing 106, a tappet roller 108, and a tappet pin 110; the tappet assembly 101 is vertically moved by a camshaft 112. The tappet assembly 101 then moves the plunger 114. Two different tappet positions are shown, where position (A) is the bottom dead center (BDC) position 120 and position (B) is the top dead center (TDC) position 122. In a conventional design, each tappet pin 110 has a centerline 116 (shown in dashed lines) leading to a specific position at BDC 120, and each tappet guide hole 102 terminates at an end portion 118.

[0006] One problem with the conventional design is that the tappet assembly 101 may fail if the centerline 116 of the tappet pin 110 falls below the end portion 118 of the tappet guide hole 102 during the BDC position 120. High-speed engine operation exacerbates and accelerates this failure. Even if the centerline 116 extends a few millimeters beyond the end portion 118, the tappet assembly 101 may still fail. Therefore, an improved design for the fuel pump housing used with the tappet assembly is still needed to reduce such failures. Summary of the Invention

[0007] According to this disclosure, various embodiments of a fuel pump housing are disclosed. The fuel pump housing includes: at least one tappet housing portion configured to receive at least one tappet assembly; and a main bore portion fluidly connected to the at least one tappet housing portion, the main bore portion being configured to receive a camshaft. The main bore portion includes an uncut portion and at least one pressure relief cut-out portion adjacent to the at least one tappet housing portion. The uncut portion defines a first centerline, and the pressure relief cut-out portion defines a second centerline offset from the first centerline.

[0008] In some examples, the first centerline is offset from and aligned with the longitudinal axis of the camshaft. In some examples, the second centerline is aligned with the longitudinal axis of the housing and positioned closer to at least one tappet housing portion than the first centerline. In some examples, at least one pressure relief cutout is formed to increase the clearance between the outer surface of the camshaft's cam lobe and the inner wall of the main bore portion. In some examples, at least one pressure relief cutout has a length shorter than the diameter of the corresponding tappet housing portion. In some examples, the housing is made of a single, integral metal piece.

[0009] In some examples, the housing also includes a side bearing portion positioned adjacent to the main bore portion and sharing a central axis with a second centerline. In some examples, fillets are formed at the transition portion between one of the side bearing portions and the main bore portion to reduce sharp edges at the transition portion. In some examples, fillets are formed at the transition portion between at least one tappet housing portion and at least one pressure relief cutout portion to reduce sharp edges at the transition portion.

[0010] In some examples, at least one tappet housing portion is a plurality of tappet housing portions, and one or more of at least one pressure relief cutout portion has a length spanning the diameter of at least two of the plurality of tappet housing portions. In some examples, a single, continuous pressure relief cutout portion has a length spanning the diameter of the plurality of tappet housing portions. A fuel pump system is also disclosed, comprising: a fuel pump housing as described above; a camshaft received in a main bore portion and operatively coupled to at least one tappet assembly; and at least one tappet assembly received in at least one tappet housing portion.

[0011] Furthermore, various embodiments of a fuel pump system for an engine are disclosed. The fuel pump system includes at least one tappet assembly, a camshaft operatively coupled to the at least one tappet assembly, and a fuel pump housing. The fuel pump housing includes: at least one tappet housing portion configured to receive the at least one tappet assembly; and a main bore portion fluidly connected to the at least one tappet housing portion, the main bore portion being configured to receive the camshaft. The main bore portion includes an uncut portion and at least one pressure relief cut-out portion adjacent to the at least one tappet housing portion. The uncut portion defines a first centerline, and the pressure relief cut-out portion defines a second centerline offset from the first centerline.

[0012] In some examples, the first centerline is offset from the central longitudinal axis of the housing and aligned with the longitudinal axis of the camshaft. In some examples, the second centerline is aligned with the central longitudinal axis of the housing and positioned closer to at least one tappet housing portion than the first centerline. In some examples, at least one pressure relief cutout is formed to increase the clearance between the outer surface of the camshaft's camshaft convex angle and the inner wall of the main bore portion. In some examples, the housing is made of a single, integral metal piece.

[0013] In some examples, the fuel pump housing also includes a side bearing portion positioned adjacent to the main bore portion and sharing a central axis with a second centerline. In some examples, fillets are formed at the transition portion between one of the side bearing portions and the main bore portion to reduce sharp edges at the transition portion. In some examples, fillets are formed at the transition portion between at least one tappet housing portion and at least one pressure relief cutout portion to reduce sharp edges at the transition portion.

[0014] Furthermore, various embodiments of an engine are disclosed. The engine includes a fuel pump system, a plurality of pistons operatively coupled to the fuel pump system, and a crankshaft operatively coupled to the plurality of pistons. The fuel pump system includes at least one tappet assembly, a camshaft operatively coupled to the at least one tappet assembly, and a fuel pump housing. The fuel pump includes: at least one tappet housing portion configured to receive the at least one tappet assembly; and a main bore portion fluidly connected to the at least one tappet housing portion. The main bore portion is configured to receive the camshaft. The main bore portion includes an uncut portion and at least one pressure relief cut portion adjacent to the at least one tappet housing portion. The uncut portion defines a first centerline, and the pressure relief cut portion defines a second centerline offset from the first centerline.

[0015] Additional features and advantages of this disclosure will become apparent to those skilled in the art when considering the following detailed description of exemplary embodiments of what is currently considered the best mode of carrying out this disclosure. Attached Figure Description

[0016] The detailed description of the accompanying drawings refers specifically to the drawings, in which:

[0017] Figure 1 shows a fuel pump housing with tappet assemblies in the BDC and TDC positions;

[0018] Figure 2 The pump casing with a pressure relief cutout is shown;

[0019] Figure 3 This shows a perspective from an angle. Figure 2 The shell; and

[0020] Figure 4 This shows the view of the camshaft with tappet assembly as observed along the central axis of the camshaft. Figure 2 and Figure 3 The shell.

[0021] Figure 5 Showing the portion with the pressure relief cut Figure 2 An alternative design for the pump housing.

[0022] Figure 6 A schematic diagram of a vehicle implementing an engine with a fuel pump housing according to an example disclosed herein. Detailed Implementation

[0023] The embodiments described herein are not intended to be exhaustive or to limit the disclosure to its precise form. Rather, the embodiments chosen for description have been selected to enable those skilled in the art to practice this disclosure.

[0024] refer to Figure 2The image shows a housing 200 for a common rail multi-cylinder fuel pump used in an engine, such as an internal combustion engine. In some examples, the housing 200 can be formed by cutting a single integral metal piece, while in other examples, the housing 200 can be formed by attaching two or more separate pieces together, such as by welding. The housing 200 includes a main bore portion 202, a pair of side bearing portions 210 positioned on and adjacent to either side of the main bore portion 202, and one or more tappet housing portions 216. The main bore 202 accommodates a camshaft 112, and the tappet housing portion 216 accommodates the tappet assembly 101 mentioned in FIG. 1. The main bore 202 includes an uncut portion 206 and a pressure relief cut-out portion 208. In some examples, the transition portion between the side bearings 210A or 210B and the main bore 202 may include a fillet 204, which is etched into the housing 200 to reduce sharp edges in the transition portion. In some examples, the fillet 204 may be implemented when the transition portion has a right angle. In some examples, additional fillets (not shown) may also be formed at the transition between the tappet housing portion 216 and the pressure relief cutout portion 208 of the main bore 202.

[0025] The difference between the uncut portion 206 and the pressure relief cut portion 208 lies in their centerlines. A centerline is the central axis of the cross-sectional area of ​​a component. In the example shown, centerline 212 ( Figure 2 The dashed line in the figure represents the central axis of the uncut portion 206, and the central line 214 ( Figure 2 The solid line in the figure represents the central axis of the pressure relief cut portion 208. A pressure relief cut is defined as a cut or engraving made into the housing 200 at the main hole 202, such that the centerline 214 of the pressure relief cut portion 208 is offset from the centerline 212 of the remaining uncut portion 206 of the main hole 202. In other words, centerlines 212 and 214 are offset from each other due to the pressure relief cut formed in the main hole 202. As shown, the pressure relief cut portion 208 is positioned closer to or closer to the tappet housing portion 216. The positioning of the pressure relief cut portion 208 achieves the offset between centerlines 212 and 214.

[0026] In some examples, the deviation causes the centerline 214 of the pressure relief cut to be closer to or closer to the tappet housing portion 216 by a certain distance than the uncut centerline 212. In some examples, the distance of the deviation may be less than 1 mm, between 1 mm and 2 mm, between 2 mm and 3 mm, or greater than 3 mm. The centerline 214 of the pressure relief cut portion 208 is also the centerline of the side bearing 210. That is, the side bearing 210 and the pressure relief cut portion 208 share the same central axis, and this central axis can be defined as the central longitudinal axis of the housing 200.

[0027] The main bore 202 is partially offset from the side bearing 210 because the centerline 212 of the uncut portion 206 of the main bore 202 is positioned below the centerline 214 (which is also the central axis of the side bearing 210) by a predetermined distance, for example, less than 1 mm, between 1 mm and 2 mm, between 2 mm and 3 mm, or greater than 3 mm, depending on the situation. Thus, the centerline 212 of the uncut portion 206 is offset from the central longitudinal axis of the housing 200 defined by the centerline 214. When the housing 200 is implemented together with the tappet assembly (or multiple tappet assemblies) 101 and crankshaft 112 shown in FIG. 1, the central longitudinal axis of the crankshaft 112 is aligned with the centerline 212 of the uncut portion 206 (which remains offset from the centerline 214) to accommodate the centerline 116 of the tappet pin 110 falling below the end portion 118 of the tappet guide bore 102 during the BDC position 120, which is known to cause failure of the tappet assembly 101.

[0028] Figure 3 This shows a perspective from an angle. Figure 2 The configuration is described to illustrate how the pressure relief cutout 208 cuts into the wall of the main bore portion 202 of the housing 200. In some examples, the pressure relief cutout 208 begins approximately midway between the lowest and highest ends of the main bore 202 and extends toward the tappet housing portion 216. In some examples, the pressure relief cutout 208 begins closer to the tappet housing portion 216 than midway (e.g., one-third of the distance between the lowest and highest ends of the main bore 202). In some examples, the pressure relief cutout 208 is arched or semi-circular.

[0029] In some examples, when multiple pressure relief cutout portions 208 exist (each pressure relief cutout portion 208 is positioned between the uncut portion 206 and the tappet housing portion 216), two adjacent pressure relief cutout portions 208 can be separated by the uncut portion 206 between them, such as... Figure 3 As shown. In some examples, the length 218 of the pressure relief cut 208 may be wider than the length of the cam angle in the camshaft 112 and narrower than the diameter of the corresponding tappet housing portion 216.

[0030] Figure 4 This shows the section cut along the dashed line AA, from... Figure 2 The cross-sectional view of shell 200 is observed in the direction of arrow "B". Figure 4Also shown is a portion of the camshaft 112 and tappet assembly 101 (tappet roller 108 and tappet pin 110) implemented in housing 200. Specifically, the camshaft 112 has a cam angle 400 shown positioned to allow the tappet assembly 101 to be in its BDC position 120. The camshaft 112 may include a plurality of cam angles 400 along its length, and the cam angles 400 may be at different angles to each other. Moreover, the number of cam angles 400 may be equal to the number of tappet assemblies 101. As an example, the cam angles 400 have a longest diameter 402 and a shortest diameter 404, such that the BDC position 120 is reached when the tappet assembly 101 (or more specifically, the tappet roller 108) contacts the outer surface 408 of the cam angle 400 at the shortest diameter 404. Alternatively, the TDC position 122 is reached when the tappet assembly 101 contacts the cam angle 400 at the longest diameter 402.

[0031] The centerline 212 of the uncut portion 206 is located at the intersection of the two diameters 402 and 404. The centerline 214 of the pressure relief cutout portion 208 is offset from (see 410) the centerline 212 by a certain distance and is located above the centerline, closer to the tappet assembly 101. The pressure relief cutout portion 208 and the uncut portion 206 are shown with different amounts of clearance 406 between the outer surface 408 of the convex angle 400 and the inner wall 412 of the main bore portion 202. Specifically, the clearance 406, or the amount of space between the camshaft 112 and the housing 200, is larger at the pressure relief cutout portion 208 than at the uncut portion 206. In some examples, the narrowest clearance 406 must be at least 1 mm, at least 1.5 mm, at least 2 mm, at least 3 mm, or at least 5 mm, depending on the application of the housing 200. Furthermore, the convex angle 400 has an axis of rotation at the longitudinal axis of the camshaft 112, as defined by the centerline 212 of the uncut portion 206. The axis of rotation is offset from the central longitudinal axis of the housing 200 defined by the centerline 214 of the pressure relief cutout portion 208.

[0032] Figure 5 Show Figure 2 An example of an alternative configuration is provided, in which instead of multiple pressure relief cutout portions 208, there is a single pressure relief cutout 500 having a length 502 spanning the diameter of multiple pushrod housing portions 216. In such a configuration, the length 502 is greater than the diameter of each pushrod housing portion 216. Thus, instead of each pushrod housing portion 216, it has such... Figure 2 The corresponding pressure relief cut section 208 shown is... Figure 5The configuration has a single, continuous pressure relief cutout portion 500 capable of accommodating one or more (in the illustrated example, all three) tappet housing portions 216. In some examples, fewer or more tappet housing portions 216 may be present. In some examples, multiple pressure relief cutouts of different lengths may be present, such that one of the pressure relief cutouts may have a length to accommodate one tappet housing portion, while another pressure relief cutout may have different lengths to accommodate two or more tappet housing portions. Thus, the pressure relief cutout accommodating one tappet housing portion has a length smaller than the diameter of the tappet housing portion, and the pressure relief cutout accommodating multiple tappet housing portions has a length larger than the diameter of any one of the multiple tappet housing portions. Any suitable combination of lengths may be implemented as appropriate.

[0033] Figure 6 A vehicle 600 is shown implementing an engine 602, which includes a fuel pump system according to an embodiment disclosed herein. An engine control unit 604 is operatively coupled to the engine, or more specifically to the fuel pump system, to operate the fuel pump system. The fuel pump system includes a housing 200 for a common rail multi-cylinder fuel pump, a plurality of pistons 606, and a crankshaft 608. The housing 200 is operatively coupled to the pistons 606, which are operatively coupled to the crankshaft 608, as shown. The crankshaft 608 is connected to a torque converter 610 (such as a flywheel), and the torque converter 610 is operatively coupled to a transmission 612. The transmission 612 is operatively coupled to and for rotating a drive shaft 614, which is coupled to a differential 616 configured to rotate a final drive member 618, the torque generated by which is converted into rotational torque for moving the wheels 620 of the vehicle 600. For simplicity, components such as the engine, transmission, and any additional parts of the vehicle are not shown, but it should be understood that this drawing is not intended to be limiting and that any additional suitable parts, as known in the art, may be incorporated.

[0034] The advantages of the design for the fuel pump housing disclosed herein include increased versatility, such as the ability to allow multiple different applications of the camshaft to fit into the same housing without requiring adjustments to the design and dimensions to suit individual applications. Clearance helps provide additional space for the tappet follower to extend from the pump housing over the tappet bore. Additionally, the pressure relief notch improves the camshaft cam clearance, allowing multiple applications to fit into the same housing, even those with different camshaft lift requirements. Furthermore, the off-center profile of the main bore reduces the need for deburring and cleaning of the bottom surface of the housing of any burrs that may have formed and separated from the housing or camshaft.

[0035] Although this disclosure has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the spirit and scope of this disclosure as described and defined in the appended claims.

Claims

1. A fuel pump housing, comprising: At least one tappet housing portion, said at least one tappet housing portion being configured to receive at least one tappet assembly; The main bore portion is fluidly connected to the at least one tappet housing portion and is configured to receive a camshaft. as well as The side bearing portion is positioned adjacent to the main hole portion. The main bore portion includes an uncut portion and at least one pressure relief cut portion adjacent to the at least one tappet housing portion, the uncut portion defining a first centerline and the pressure relief cut portion defining a second centerline offset from the first centerline, and the side bearing portion sharing a central axis with the second centerline.

2. The fuel pump housing of claim 1, wherein the first centerline is offset from the central longitudinal axis of the housing and aligned with the longitudinal axis of the camshaft.

3. The fuel pump housing of claim 1, wherein the second centerline is aligned with the central longitudinal axis of the housing and is positioned closer to the at least one tappet housing portion than the first centerline.

4. The fuel pump housing of claim 1, wherein the at least one pressure relief cutout portion is formed to increase the clearance between the outer surface of the camshaft's convex angle and the inner wall of the main bore portion.

5. The fuel pump housing according to claim 1, wherein the at least one pressure relief cut portion has a length shorter than the diameter of the corresponding tappet housing portion.

6. The fuel pump housing according to claim 1, wherein the housing is made of a single integral metal piece.

7. The fuel pump housing of claim 1, wherein a fillet is formed at the transition portion between one of the side bearing portions and the main bore portion to reduce sharp edges at the transition portion.

8. The fuel pump housing of claim 1, wherein rounded corners are formed at the transition portion between the at least one tappet housing portion and the at least one pressure relief cut-out portion to reduce sharp edges at the transition portion.

9. The fuel pump housing of claim 1, wherein the at least one tappet housing portion is a plurality of tappet housing portions, and one or more of the at least one pressure relief cutout portion has a length spanning the diameter of at least two of the plurality of tappet housing portions.

10. The fuel pump housing of claim 9, wherein a single, continuous pressure relief cutout portion has a length spanning the diameter of the plurality of tappet housing portions.

11. A fuel pump system for an engine, comprising: At least one tappet assembly; A camshaft, which is operatively connected to the at least one tappet assembly; as well as Fuel pump housing, comprising: At least one tappet housing portion, the at least one tappet housing portion being configured to receive the at least one tappet assembly; A main bore portion, fluidly connected to at least one tappet housing portion, the main bore portion being configured to receive the camshaft; and The side bearing portion is positioned adjacent to the main hole portion. The main bore portion includes an uncut portion and at least one pressure relief cut portion adjacent to the at least one tappet housing portion, the uncut portion defining a first centerline and the pressure relief cut portion defining a second centerline offset from the first centerline, and the side bearing portion sharing a central axis with the second centerline.

12. The fuel pump system of claim 11, wherein the first centerline is offset from the central longitudinal axis of the housing and aligned with the longitudinal axis of the camshaft.

13. The fuel pump system of claim 11, wherein the second centerline is aligned with the central longitudinal axis of the housing and is positioned closer to the at least one tappet housing portion than the first centerline.

14. The fuel pump system of claim 11, wherein the at least one pressure relief cut-out portion is formed to increase the clearance between the outer surface of the camshaft convex angle and the inner wall of the main bore portion.

15. The fuel pump system of claim 11, wherein the housing is made of a single integral metal piece.

16. The fuel pump system of claim 11, wherein a fillet is formed at the transition portion between one of the side bearing portions and the main bore portion to reduce sharp edges at the transition portion.

17. The fuel pump system of claim 11, wherein rounded corners are formed at the transition portion between the at least one tappet housing portion and the at least one pressure relief cut-out portion to reduce sharp edges at the transition portion.

18. An engine comprising: Fuel pump system, the fuel pump comprising: Multiple tappet assemblies; A camshaft, operatively connected to the plurality of tappet assemblies; and Fuel pump housing, the fuel pump housing comprising: Multiple tappet housing portions, the multiple tappet housing portions being configured to receive a corresponding one of the multiple tappet assemblies; and The main bore portion, which is fluidly connected to the plurality of tappet housing portions, is configured to receive the camshaft. The main hole portion includes an uncut portion and a single pressure relief cut portion adjacent to the plurality of tappet housing portions. The uncut portion defines a first centerline and the pressure relief cut portion defines a second centerline offset from the first centerline. The pressure relief cut portion has a length along the second centerline spanning at least two of the plurality of tappet housing portions, and the at least two of the plurality of tappet housing portions are spaced apart from each other along the second centerline. A plurality of pistons, said plurality of pistons being operatively coupled to said fuel pump system; and A crankshaft, which is operatively connected to the plurality of pistons.

Images