Ram pump actuator and method of assembly thereof

Abstract

A pump actuator (10, 110) for use between a cam (12) and a pump (20) includes an outer body (130), an inner body (132), a shaft (166), and a bearing (170). The outer body (130) has an outer body inner surface (138). The inner body (132) is received by the outer body (130). The inner body (132) has an inner body outer surface (136, 236, 336). The shaft (166) is supported by the inner body (132). The bearing (170) is supported on the shaft (166). The inner body (132) includes at least one stamped feature (134) that protrudes outward from the inner body outer surface (136, 236, 336). The at least one stamped feature (134) is configured to form an interference fit with the outer body inner surface (130).

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of Indian Provisional Application No. 202011053945, filed on December 11, 2020. The disclosure of the above application is incorporated herein by reference. Technical Field

[0003] This disclosure relates generally to a pump actuator or roller pusher, and more specifically to a pump actuator having a stamped inner body, wherein the inner body is assembled with an outer body using a press-fit operation. Background Technology

[0004] The pump actuator is an integrated component of a spark-ignition direct injection (SIDI) fuel system. It redirects the rotational motion of the fuel pump cam into linear fuel pump drive motion. The pump actuator is a roller follower sandwiched between the cam and the gas-in-cylinder direct injection (GDI) pump. During operation, the pump actuator pressurizes the fuel inside the GDI pump to maintain pressure within the fuel rails. Typical direct injection fuel pressures can be up to 90 times higher than conventional fuel pressures. There is a desire to increase load-bearing capacity and reduce friction in the pump actuator. Furthermore, there is a desire to reduce costs through alternative geometries, materials, and manufacturing processes. Currently produced pump actuator bodies consist of a single-piece cold-formed structure.

[0005] The background description provided herein is for the purpose of generally presenting the context of this disclosure. The work of the currently designated inventor, as described to some extent in this background section and in various aspects of the specification which may not otherwise qualify as prior art at the time of filing, is neither expressly nor implied to be acknowledged as prior art to this disclosure. Summary of the Invention

[0006] A pump actuator for use between a cam and a pump includes an outer body, an inner body, a shaft, and a bearing. The outer body has an inner surface. The inner body is received by the outer body. The inner body has an outer surface. The shaft is supported by the inner body. The bearing is supported on the shaft. The inner body includes at least one stamped feature projecting outward from the outer surface of the inner body. The at least one stamped feature is configured to form an interference fit with the inner surface of the outer body.

[0007] According to an additional feature, the at least one stamped feature includes at least one wedge-shaped geometry having a sloping surface thereon. In other examples, the at least one stamped feature includes at least one trapezoidal geometry having a sloping surface thereon. In other examples, the at least one stamped feature includes at least one shallow concave geometry having a sloping surface thereon.

[0008] Among other features, the at least one stamped feature includes a plurality of stamped features formed around the inner body. The plurality of stamped features and the inner surface of the outer body undergo localized elastic deformation. The inner body and the outer body are press-fitted together. The inner body also includes an angled support web. In the example, the plurality of stamped features includes (i) a first pair of stamped features having opposing first and second stamped features; and (ii) a second pair of stamped features having opposing third and fourth stamped features.

[0009] A pump actuator for use between a cam and a pump, and constructed according to another example, includes an outer body, an inner body, a shaft, and a bearing. The outer body has an inner surface. The inner body is received by the outer body. The inner body has an outer surface. The bearing is supported on the shaft. The inner body includes opposing stamped features projecting outward from the outer surface of the inner body. The opposing stamped features are configured to form an interference fit with the inner surface of the outer body.

[0010] In other features, opposing stamped features include a first pair of stamped features and a second pair of stamped features. The first pair of stamped features includes opposing first and second stamped features. The second pair of stamped features includes opposing third and fourth stamped features. In one arrangement, each of the stamped features includes at least one wedge-shaped geometry having a sloping surface thereon. In other examples, each of the stamped features includes at least one trapezoidal geometry having a sloping surface thereon. In other examples, each of the stamped features includes at least one shallow concave geometry having a sloping surface thereon.

[0011] A method of assembling a pump actuator for use between a cam and a pump includes: providing an outer body; providing an inner body; outwardly deflecting a portion of the inner body; and slidably advancing the outer body and the inner body relative to one of the outer body and the inner body. The outer body has an inner surface. The inner body has an outer surface. The outwardly deflected portion of the inner body forms a plurality of stamped features extending outwardly from the outer surface of the inner body. The stamped features slidably engage along the inner surface of the outer body, thereby forming an interference fit between the outer body and the inner body.

[0012] Among the additional features, the deflecting inner body portion includes one of a wedge-shaped geometry, a trapezoidal geometry, and a shallow concave geometry forming a sloping surface thereon. During slidable advancement, the sloping surface is slidably advanced along the inner surface of the outer body. During slidable advancement, the inner and outer bodies are simultaneously aligned relative to each other. In one example, the outer body is positioned around the upper surface of the inner body. The outer body is advanced downwards such that its bottom surface straddles the sloping surface. In another example, the outer body is positioned around the upper surface of the inner body. The inner body is advanced upwards such that its bottom surface straddles the sloping surface. Attached Figure Description

[0013] This disclosure will be more fully understood in light of the specific embodiments and accompanying drawings, wherein:

[0014] Figure 1 This is a front perspective view of a pump actuator arranged between a cam on a camshaft and a high-pressure GDI pump, according to an example of this disclosure.

[0015] Figure 2A This is a top view of a pump actuator constructed according to an example of this disclosure;

[0016] Figure 2B yes Figure 2A A cross-sectional view of the pump actuator, showing the wedge-shaped protrusion on the inner body;

[0017] Figure 3A yes Figure 2A First perspective view of the inner body of the pump actuator;

[0018] Figure 3B yes Figure 3A Detailed view of the wedge-shaped protrusion of the inner body;

[0019] Figure 3C It was taken along line 3C-3C. Figure 3B A cross-sectional view of the wedge-shaped protrusion;

[0020] Figure 4A It is a first perspective view of the inner body of the pump actuator, the inner body including a trapezoidal protrusion constructed according to additional features of this disclosure;

[0021] Figure 4B yes Figure 4A Detailed view of the trapezoidal protrusion of the inner main body;

[0022] Figure 4C It was cut along line 4C-4C. Figure 4B A cross-sectional view of the trapezoidal protrusion;

[0023] Figure 5AIt is a first perspective view of the inner body of the pump actuator, the inner body including a shallow concave protrusion constructed according to additional features of this disclosure;

[0024] Figure 5B yes Figure 5A Detailed view of the shallow concave protrusion of the inner body;

[0025] Figure 5C It was taken from line 5C-5C. Figure 5B A cross-sectional view of the shallow concave protrusion;

[0026] Figures 6A to 6C yes Figure 4A The inner body is slidably pushed into the outer body, thereby achieving a press fit sequence view between the inner body and the outer body at the wedge-shaped protrusion;

[0027] Figures 7A to 7C yes Figure 5A The inner body is slidably pushed into the outer body, thereby achieving a press fit sequence view between the inner and outer bodies at the trapezoidal protrusion; and

[0028] Figures 8A to 8C yes Figure 5A The inner body is slidably pushed into the outer body, thereby achieving a press fit sequence view between the inner and outer bodies at the shallow concave protrusion. Detailed Implementation

[0029] First refer to Figure 1 The diagram illustrates a pump actuator or roller pusher constructed according to an example of this disclosure, and is generally identified by reference numeral 10. The pump actuator 10 is shown as operatively engaged with a cam 12 on a camshaft 14. Translation of the pump actuator 10 pressurizes fuel within the GDI pump 20. The pump actuator 10 utilizes the rotational movement of the camshaft 14 and converts that rotational movement into linear fuel pump drive motion.

[0030] Now go to Figures 2A to 3C This diagram illustrates a pump actuator constructed according to an example of this disclosure, and is generally identified by reference numeral 110. As will be understood from the following discussion, the pump actuator 110 is a two-piece pump actuator having a body assembly 122 comprising an outer body or sleeve 130 and an inner body or cup 132. The outer body 130 serves as a guide in the engine cylinder bore. The inner body 132 supports the functional load path (via bearing support at the pump pad contact point). The inner body 132 also includes an angled support web 150 for increased strength and stiffness.

[0031] According to this disclosure, the inner body 132 may include stamped features 134 that may project outwardly beyond the outer diameter or surface 136 of the inner body 132. The stamped features 134 may include two pairs of opposing stamped features 134, including opposing first and second stamped features and opposing third and fourth stamped features. When assembled to the outer body 130, the relative positions of the stamped features 134 may affect a robust interference fit. The stamped features 134 may be stamped from the interior of the inner body 132 to form outwardly extending protrusions. The inner body 132 is inserted relative to the outer body 130 such that the stamped features 134 are positioned (as will be described herein with respect to...) Figures 6A to 6C During assembly, an interference fit or press fit is formed with the inner diameter or surface 138 of the outer body 130. Due to stamping, the stamped feature 134 can obtain a wedge geometry with a ramped surface 140. In this respect, the ramped surface 140 of the wedge feature 134 will facilitate a smooth and progressive assembly of the inner body 132 and the outer body 130.

[0032] Further reference Figures 6A to 6C An exemplary method for assembling the inner body 132 and the outer body 130 will be described. In one example, the outer body 130 may be positioned around the upper surface 146 of the inner body 132. The inner body 132 may be advanced generally upward (from...) Figure 6A The approximate location shown is to Figure 6B The approximate location shown and eventually to Figure 6C (as shown in the diagram). During the upward advancement of the inner body 132, the inclined surface 140 of the stamped feature 134 initially crosses the bottom surface 148 of the outer body 130. It should be understood that, due to an interference fit or press fit, the outer body 130 and / or the inner body 132 may slightly deform to accommodate the stamped feature 134. It will be further understood that, although the above discussion has been described as the inner body 132 being advanced upward into the outer body 130, the outer body 130 may be advanced downward relative to the inner body 132. In other arrangements, both the inner body 132 and the outer body 130 may advance towards each other simultaneously.

[0033] The wedge-shaped surface 140 and the inner surface 138 of the outer body 130 will undergo localized elastic deformation. Friction between the surfaces will prevent the outer body 130 and the inner body 132 from disengaging during operation. An additional advantage is that the wedge-shaped feature 134 facilitates the alignment of the outer body 130 and the inner body 132 during simultaneous assembly. Alignment of the inner and outer bodies 130, 132 can be completed in a single operation. In this respect, no additional welding or other assembly operations are required. Cost reduction is achieved by avoiding such additional assembly steps.

[0034] The pump actuator 110 may also include a shaft 166 and a bearing 170. In a non-limiting example, the bearing 170 may typically include an outer roller 172 and a plurality of inner rollers (not specifically shown). A plurality of bores 178 are shown around the inner body 132.

[0035] Now go to Figures 4A to 4C and Figures 7A to 7C The following describes an inner body 232 constructed according to an additional example of this disclosure. Unless otherwise described herein, identical features are denoted by the same reference numerals as inner body 132 and incremented by 100. Inner body 232 may include stamped features 234 that may project outwardly beyond the outer diameter or surface 236 of inner body 232. Stamped features 234 may include two pairs of opposing stamped features 234, including opposing first and second stamped features and opposing third and fourth stamped features. When assembled to outer body 130, the relative positions of the stamped features 234 may affect a robust interference fit.

[0036] exist Figures 4A to 4C In the example shown, the stamped feature is in the form of a trapezoidal protrusion. The stamped feature 234 can be stamped from the inside of the inner body 232 to form an outwardly extending protrusion. The inner body 232 is inserted relative to the outer body 130 such that the stamped feature 234 is positioned (as will be discussed herein)... Figures 7A to 7C During assembly, an interference fit or press fit is formed with the inner diameter or surface 138 of the outer body 130. Due to stamping, the stamped feature 234 can obtain a trapezoidal geometry with a sloping surface 240. In this respect, the sloping surface 240 of the trapezoidal feature 234 will facilitate a smooth and progressive assembly of the inner body 232 and the outer body 130.

[0037] Further reference Figures 7A to 7C An exemplary method for assembling the inner body 232 and the outer body 130 will be described. In one example, the outer body 130 may be positioned around the upper surface 246 of the inner body 232. The inner body 232 may be advanced generally upward (from...) Figure 7A The approximate location shown is to Figure 7B The approximate location shown and eventually to Figure 7C (as shown in the diagram). During the upward advancement of the inner body 232, the inclined surface 240 of the stamped feature 234 initially crosses the bottom surface 148 of the outer body 130. It should be understood that, due to an interference fit or press fit, the outer body 130 and / or the inner body 232 may deform slightly to accommodate the stamped feature 234. It will be further understood that, although the above discussion has been described as the inner body 232 being advanced upward into the outer body 130, the outer body 130 may be advanced downward relative to the inner body 232. In other arrangements, the inner body 232 and the outer body 130 may both advance toward each other simultaneously.

[0038] The trapezoidal surface 240 and the inner surface 138 of the outer body 130 will undergo localized elastic deformation. Friction between the surfaces will prevent the outer body 230 and the inner body 132 from disengaging during operation. An additional advantage is that the trapezoidal feature 134 facilitates the alignment of the outer body 130 and the inner body 232 during simultaneous assembly. Alignment of the inner and outer bodies 130, 232 can be completed in a single operation. In this respect, no additional welding or other assembly operations are required. Cost reduction is achieved by avoiding such additional assembly steps.

[0039] Now go to Figures 5A to 5C and Figures 8A to 8C The following describes an inner body 332 constructed according to an additional example of this disclosure. Unless otherwise described herein, the same features are denoted by the same reference numerals as the inner body 132 and increased by 200. The inner body 332 may include stamped features 334 that may project outwardly beyond the outer diameter or surface 336 of the inner body 332. The stamped features 334 may include two pairs of opposing stamped features 334, including opposing first and second stamped features and opposing third and fourth stamped features. When assembled to the outer body 130, the relative positions of the stamped features 334 may affect a robust interference fit.

[0040] exist Figures 5A to 5C In the example shown, the stamped feature is in the form of a spherical or shallowly concave protrusion. The stamped feature 334 can be stamped from the interior of the inner body 332 to form an outwardly extending protrusion. The inner body 332 is inserted relative to the outer body 130 such that the stamped feature 334 is positioned (as will be discussed herein regarding...) Figures 8A to 8C During assembly, an interference fit or press fit is formed with the inner diameter or surface 138 of the outer body 130. Due to stamping, the stamped feature 334 can obtain a shallow concave geometry with a sloping surface 340. In this respect, the sloping surface 340 of the shallow concave feature 334 will facilitate a smooth and progressive assembly of the inner body 332 and the outer body 130.

[0041] Further reference Figures 8A to 8C An exemplary method for assembling the inner body 332 and the outer body 130 will be described. In one example, the outer body 130 may be positioned around the upper surface 346 of the inner body 332. The inner body 332 may be advanced generally upward (from...) Figure 8A The approximate location shown is to Figure 8B The approximate location shown and eventually to Figure 8C(as shown in the diagram). During the upward advancement of the inner body 332, the inclined surface 340 of the stamped feature 334 initially crosses the bottom surface 148 of the outer body 130. It should be understood that, due to an interference fit or press fit, the outer body 130 and / or the inner body 332 may slightly deform to accommodate the stamped feature 334. It will be further understood that, although the above discussion has been described as the inner body 332 being advanced upward into the outer body 130, the outer body 130 may be advanced downward relative to the inner body 332. In other arrangements, the inner body 332 and the outer body 130 may both advance toward each other simultaneously.

[0042] The shallow concave surface 340 and the inner surface 138 of the outer body 130 will undergo localized elastic deformation. Friction between the surfaces will prevent the outer body 330 and the inner body 132 from disengaging during operation. An additional advantage is that the shallow concave feature 134 facilitates the alignment of the outer body 130 and the inner body 332 during simultaneous assembly. Alignment of the inner and outer bodies 130, 332 can be completed in a single operation. In this respect, no additional welding or other assembly operations are required. Cost reduction is achieved by avoiding such additional assembly steps.

[0043] By achieving an interference fit between the outer surfaces 136, 236, 336 of the inner bodies 132, 232, 332 and the inner surface 138 of the outer body 130, the inner and outer bodies of the pump actuator can be securely joined together without any alternative and / or supplementary fixing components and / or methods. This press-fit solution provides a more cost-effective and easier method for manufacturing pump actuator assemblies compared to prior art products. In contrast, some prior art examples require welding the inner and outer bodies together. In production, laser welding requires capital investment and additional cycle time. Furthermore, the inner and outer bodies need to be perfectly aligned before welding to avoid any bearing verticality issues. The press-fit solution described herein allows the two bodies to be assembled during a simultaneous alignment operation, thus avoiding the costs of laser welding.

[0044] The foregoing description of these examples has been provided for illustrative and descriptive purposes. It is not intended to be exhaustive or limiting of this disclosure. Elements or features of a particular example are generally not limited to that particular example, but are interchangeable and applicable where applicable, even if not specifically shown or described. They may also be changed in many ways. Such variations should not be considered as departing from this disclosure, and all such modifications are intended to be included within the scope of this disclosure.

Claims

1. A pump actuator for use between a cam and a pump, the pump actuator comprising: an outer body having an outer body inner surface; an inner body received by the outer body, the inner body having an inner body outer surface; a shaft supported by the inner body; and a bearing supported on the shaft; wherein the inner body of the pump actuator includes a plurality of stamped features that project outwardly from the inner body outer surface and are configured to simultaneously (1) form an interference fit between the outer body and inner body of the pump actuator and (2) align the outer body and inner body of the pump actuator relative to one another.

2. The pump actuator of claim 1, wherein at least one stamped feature includes at least one wedge-shaped geometry having a ramped surface thereon.

3. The pump actuator of claim 1, wherein at least one stamped feature includes at least one trapezoidal geometry having a ramped surface thereon.

4. The pump actuator of claim 1, wherein at least one stamped feature includes at least one dimple-shaped geometry having a ramped surface thereon.

5. The pump actuator of claim 1, wherein the plurality of stamped features are formed around the inner body.

6. The pump actuator of claim 5, wherein the plurality of stamped features and the outer body inner surface undergo local elastic deformation.

7. The pump actuator of claim 1, wherein the inner body and the outer body are press fit together.

8. The pump actuator of claim 1, wherein the inner body further includes an angled support web.

9. The pump actuator of claim 1, wherein the plurality of stamped features include: a first pair of stamped features having opposing first and second stamped features; and a second pair of stamped features having opposing third and fourth stamped features.

10. A pump actuator for use between a cam and a pump, the pump actuator comprising: an outer body having an outer body inner surface; an inner body received by the outer body, the inner body having an inner body outer surface; a shaft supported by the inner body; and a bearing supported on the shaft; wherein the inner body of the pump actuator includes a plurality of opposing stamped features that project outwardly from the inner body outer surface and are configured to simultaneously (1) form an interference fit between the outer body and inner body of the pump actuator and (2) align the outer body and inner body of the pump actuator relative to one another.

11. The pump actuator of claim 10, wherein the plurality of opposing stamped features include: a first pair of stamped features having opposing first and second stamped features; and a second pair of stamped features having opposing third and fourth stamped features. ​ ​ ​ ​ 12. The pump actuator of claim 11, wherein each of the plurality of opposing swage features comprises a wedge geometry having a ramped surface thereon.

13. The pump actuator of claim 11, wherein each of the plurality of opposing swage features comprises a trapezoidal geometry having a ramped surface thereon.

14. The pump actuator of claim 11, wherein each of the plurality of opposing swage features comprises a dimple geometry having a ramped surface thereon.

15. The pump actuator of claim 10, wherein the inner body and the outer body are press fit together.

16. A method of assembling a pump actuator for use between a cam and a pump, the method comprising: providing an outer body having an outer body inner surface; providing an inner body having an inner body outer surface; offsetting portions of the inner body outward, forming a plurality of swage features extending outward from the inner body outer surface and configured to simultaneously (1) form an interference fit between the outer body and the inner body of the pump actuator and (2) align the outer body and the inner body of the pump actuator relative to one another; slidably advancing one of the outer body and the inner body relative to the other of the outer body and the inner body such that the plurality of swage features slidably mate along the outer body inner surface, thereby forming the interference fit between the outer body and the inner body.

17. The method of claim 16, wherein offsetting portions of the inner body outward further comprises: forming one of a wedge geometry, a trapezoidal geometry, and a dimple geometry having a ramped surface thereon, wherein the ramped surface is slidably advanced along the outer body inner surface during the slidably advancing.

18. The method of claim 17, wherein the slidably advancing further comprises simultaneously aligning the outer body and the inner body relative to one another.

19. The method of claim 17, wherein the slidably advancing further comprises: positioning the outer body about an upper surface of the inner body; and advancing the outer body downward such that a bottom surface of the outer body rides across the ramped surface.

20. The method of claim 17, wherein the slidably advancing further comprises: positioning the outer body about an upper surface of the inner body; and advancing the inner body upward such that a bottom surface of the outer body rides across the ramped surface. ​ ​

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