Press fitting jig

Abstract

The utility model relates to a press-fitting jig for press-fitting a balance block on a crankshaft, in particular to a press-fitting jig for preventing deviation between the balance block and an expected circumferential mounting position relative to the crankshaft in the circumferential direction. The press fitting jig comprises a jig body, a first positioning part and a second positioning part. The jig body is cylindrical or partially cylindrical so as to be suitable for being arranged on the crankshaft in a sliding and sleeving mode relative to the crankshaft in the axial direction. The jig body further comprises a pressure bearing end face and a pressure applying end face which are opposite in the axial direction. The pressure bearing end face is suitable for bearing press-fitting force from press-fitting equipment, and the pressure applying end face is suitable for applying the press-fitting force to the balance block. The first positioning part is arranged on the jig body and suitable for being directly or indirectly matched with the crankshaft so that the press-fitting jig can be positioned relative to the crankshaft in the circumferential direction. The second positioning part is arranged on the jig body and suitable for being directly or indirectly matched with the balance block so that the press-fitting jig can be positioned relative to the balance block in the circumferential direction.

Description

Technical Field

[0001] This utility model relates to the field of press-fit fixtures, and more specifically, to a press-fit fixture for pressing a balance block onto a crankshaft. Background Technology

[0002] Devices such as scroll compressors include a crankshaft and a counterweight mounted on it. Due to the presence of an eccentric portion, the crankshaft generates an unbalanced centrifugal force during rotation. This unbalanced centrifugal force causes unwanted vibrations during crankshaft rotation. The counterweight alters the mass distribution of the crankshaft, helping to eliminate the generation of unbalanced centrifugal forces and thus suppressing vibrations during rotation. The counterweight needs to be accurately positioned relative to the crankshaft in the circumferential direction to avoid deviations between its actual and expected circumferential positions; otherwise, it will be difficult to prevent the generation of unbalanced centrifugal forces during crankshaft rotation. Utility Model Content

[0003] In view of this, the present invention proposes a press-fit fixture for press-fitting a balance block onto a crankshaft, and in particular a press-fit fixture for preventing deviation in the circumferential direction between the balance block and the expected circumferential mounting position relative to the crankshaft.

[0004] The press-fit fixture includes a fixture body, a first positioning part, and a second positioning part. The fixture body is cylindrical or partially cylindrical to be slidably fitted onto the crankshaft relative to it along the axial direction. The fixture body also includes a bearing end face and a pressing end face opposite each other in the axial direction. The bearing end face is adapted to withstand the press-fitting force from the press-fitting equipment, and the pressing end face is adapted to apply the press-fitting force to the counterweight. The first positioning part is provided on the fixture body and is adapted to directly or indirectly cooperate with the crankshaft to position the press-fit fixture relative to the crankshaft in the circumferential direction. The second positioning part is provided on the fixture body and is adapted to directly or indirectly cooperate with the counterweight to position the press-fit fixture relative to the counterweight in the circumferential direction.

[0005] In this embodiment of the invention, the fixture body is cylindrical or partially cylindrical. This shape of fixture body adapts to the outer surface of the crankshaft, allowing the press-fit fixture to be fitted onto the crankshaft and, at least during the press-fitting process, to slide axially on the crankshaft and be confined relative to the crankshaft in the radial direction.

[0006] The bearing end face and the applying end face are axially opposed. During the press-fitting process, at least an axial pressing force from the press-fitting equipment is applied to the bearing end face at one end of the press-fitting fixture in the axial direction, and applied to the balance block by the applying end face at the other end of the press-fitting fixture in the axial direction, thereby pressing the balance block onto the crankshaft. The bearing end face and the applying end face located in the axial direction reduce the press-fitting stroke of the press-fitting equipment.

[0007] During the press-fitting process, the first positioning part cooperates with the crankshaft, and the second positioning part cooperates with the balance block. Together, they achieve the circumferential positioning of the crankshaft and the balance block. This prevents the crankshaft and the balance block from moving in the circumferential direction during the press-fitting process, thus ensuring their accurate circumferential positioning after press-fitting.

[0008] In one example, the first positioning part is a through groove that extends from the outer peripheral surface of the fixture body to its inner peripheral surface to penetrate the fixture body, and the length direction of the through groove is substantially parallel to the axial direction.

[0009] In this embodiment of the invention, the first positioning part is a through groove extending from the outer circumferential surface of the fixture body to its inner circumferential surface. The through groove is positioned relative to a positioning pin suitable for engaging with the crankshaft oil hole. The positioning pin passes through the through groove and the crankshaft oil hole in sequence in the radial direction. This through groove structure facilitates the pre-installation of the press-fit fixture between the crankshaft and the balance block. The length direction of the through groove is substantially parallel to the axial direction. During the press-fitting process, the through groove of the press-fit fixture with the above-described structure allows the positioning pin to move axially relative to the press-fit fixture, while preventing the positioning pin from moving circumferentially relative to the press-fit fixture, thereby maintaining the circumferential position of the balance block relative to the crankshaft during the press-fitting process.

[0010] In one example, the through groove extends axially to the pressure end face to form an opening on the pressure end face.

[0011] In this embodiment of the invention, the opening formed on the pressure-applying end face facilitates the fitting and installation of the press-fit fixture with the crankshaft and balance weight. If the through groove does not extend to the pressure-applying end face, that is, the through groove is closed axially, the press-fit fixture needs to be installed on the crankshaft first, and then the locating pin needs to be inserted into the oil hole of the crankshaft. This installation method is inconvenient. The reason is that the above installation method requires first aligning the through groove of the fixture with the oil hole of the crankshaft, and then inserting the locating pin through the through groove into the oil hole, which makes accurate alignment and insertion difficult. The through groove in the above structure extends axially to the pressure-applying end face and forms an opening on the pressure-applying end face. Before installing the press-fit fixture, the locating pin can first mate with the crankshaft oil hole. That is, the locating pin can be inserted into the crankshaft oil hole when it is exposed, and then the press-fit fixture is installed, so that the locating pin enters the through groove from the opening on the pressure-applying end face. This operation method is easier and more convenient.

[0012] In one example, the second positioning part is a lug that protrudes outward from the outer periphery of the fixture body.

[0013] In this embodiment of the invention, the second positioning part is in the shape of a lug. This shape of the second positioning part is simple in structure, easy to manufacture, and easy to position and cooperate with the balance block.

[0014] In one example, the press-fit fixture includes two circumferentially spaced lugs, each lug having a locating surface on one side circumferentially. The locating surfaces are adapted to abut against the locating surface of the counterweight to position the press-fit fixture relative to the counterweight circumferentially, and the two locating surfaces of the two lugs are adjacent in the circumferential direction.

[0015] In this embodiment of the invention, each of the two lugs has circumferentially spaced and circumferentially adjacent positioning surfaces. Because the two positioning surfaces are adjacent circumferentially, when the two positioned surfaces of the balance block abut against the two positioning surfaces respectively, the balance block cannot rotate circumferentially clockwise or counterclockwise relative to the pressing fixture. During the pressing process, the lugs constructed as described above effectively prevent the balance block from moving circumferentially relative to the pressing fixture.

[0016] In one example, the reference line passing through the through slot and the axis of the fixture body is substantially perpendicular to the reference plane containing the two positioning surfaces.

[0017] In one example, each lug has a non-locating surface that is circumferentially opposite to the locating surface, and the first locating part is located circumferentially between the two non-locating surfaces of the two lugs and spaced apart from the two non-locating surfaces.

[0018] In this embodiment of the invention, the press-fit fixture constructed above can avoid interference between the positioning pin and the second positioning part or the balance block, which facilitates the installation and use of the press-fit fixture.

[0019] In one example, the press-fit fixture also includes a first arc transition portion and a second arc transition portion. The first arc transition portion is located at the junction of the positioning surface and the fixture body, and the second arc transition portion is located at the junction of the non-positioning surface and the fixture body. The radius of the first arc transition portion is smaller than the radius of the second arc transition portion.

[0020] In this embodiment of the invention, the difference in radius between the first and second arc transition portions increases the area of ​​the positioning surface that contacts the positioning surface of the balance block, making the positioning between the press-fit fixture and the balance block more accurate and stable, while also increasing the strength of the press-fit fixture.

[0021] In one example, a protective sleeve or protective layer is provided on the inner circumference of the fixture body, and the hardness of the protective sleeve or protective layer is lower than that of the fixture body.

[0022] In this embodiment of the invention, a protective sleeve or protective layer is provided on the inner circumferential side of the fixture body. During the pressing process, the inner circumferential side of the fixture body comes into contact with the crankshaft. The aforementioned protective sleeve or protective layer can prevent surface damage to the fixture body. In particular, it can also prevent surface damage to the crankshaft surface that mates with the sliding bearing.

[0023] In one example, the protective sleeve or layer is made at least in part of aluminum or its alloys, copper or its alloys, nylon or Teflon.

[0024] In this embodiment of the invention, the protective sleeve or protective layer made of the above-mentioned material has low hardness. In particular, Teflon has self-lubricating properties, which helps to reduce friction during the press-fitting process, thereby reducing the pressure required during the press-fitting process and further reducing the risk of damage to the crankshaft. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the embodiments will be briefly described below.

[0026] It should be understood that the following figures only show some embodiments of the present invention and should not be regarded as a limitation on the scope of the present invention.

[0027] It should also be understood that the same or similar reference numerals are used in the accompanying drawings to denote the same or similar elements.

[0028] It should also be understood that the accompanying drawings are only schematic, and the dimensions and scales of the elements in the drawings are not necessarily precise.

[0029] Figure 1A This is a structural diagram of the crankshaft and the balance weight to be installed on the crankshaft.

[0030] Figure 1B This is a structural diagram of the crankshaft and the balance weights mounted on it.

[0031] Figure 2 This is a three-dimensional structural diagram of the press-fitting fixture according to an embodiment of the present utility model.

[0032] Figure 3 It is along Figure 2 The sectional view is taken by the AA section line.

[0033] Figure 4 This is a front view of the press-fit fixture according to an embodiment of the present utility model.

[0034] Figure 5 This is a top view of the press-fit fixture according to an embodiment of the present utility model.

[0035] Figure 6 This is an exploded structural diagram of the press-fitting mechanism, which includes a crankshaft, a balance block to be installed on the crankshaft, a press-fitting fixture and a positioning pin according to an embodiment of the present invention.

[0036] Figure 7A yes Figure 6 A schematic diagram of the press-fitting mechanism.

[0037] Figure 7B It is along Figure 7A A cross-sectional view of the press-fitting mechanism taken from the BB section line.

[0038] Figure 8 yes Figure 6 A top view of the press-fitting mechanism. Detailed Implementation

[0039] The embodiments of the present invention will now be described by way of example with reference to the accompanying drawings. It should be understood that there are many ways to implement the present invention, and it should not be limited to the embodiments described below. The embodiments described below are only for a more thorough and clear understanding of the present invention.

[0040] Figure 1A This is a structural schematic diagram of the crankshaft 30 and the balance block 20 to be installed on the crankshaft. Figure 1B This is a schematic diagram of the two components installed together. By way of example only, crankshaft 30 could be a crankshaft used in equipment such as a scroll compressor. See also Figure 1A and Figure 1B The crankshaft 30 may include multiple cylindrical or near-cylindrical shaft segments, at least one of which is an eccentric shaft segment 302. The axis of the eccentric shaft segment 302 is parallel to the rotation axis R of the crankshaft 30, but does not coincide with the rotation axis R. Preferably, the crankshaft 30 for devices such as scroll compressors may include only one eccentric shaft segment 302. The eccentric shaft segment 302 may cooperate with components such as pistons and housings to form a fluid cavity with an inlet and an outlet. A drive assembly such as a motor is connected to the crankshaft 30 (not shown). After fluid is introduced into the fluid cavity through the inlet, the inlet and outlet are closed. The drive assembly drives the crankshaft 30 to rotate, and the eccentric shaft segment 302 and the piston rotate accordingly. Because the eccentric shaft segment 302 is positioned off-center from the rotation axis R of the crankshaft 30, the volume of the fluid cavity formed by the eccentric shaft segment and the piston and other components changes, and the fluid in the fluid cavity is pressurized.

[0041] The axis of the eccentric shaft segment 302 is offset from the rotation axis R of the crankshaft 30. The mass distribution of the eccentric shaft segment 302 relative to the rotation axis R is uneven. When the crankshaft 30 rotates, the eccentric shaft segment 302 therefore generates a tangential centrifugal force. This centrifugal force acts on the crankshaft 30, causing undesirable vibrations and thus reducing the rotational stability of the crankshaft 30.

[0042] To solve the above problem, the balance block 20 is assembled to the eccentric shaft section 302 of the crankshaft 30. See also Figure 1A and Figure 1BA gap 50 exists between the eccentric shaft segment 302 and the counterweight 20. When the crankshaft 30 operates in a device such as a scroll compressor, the gap 50 is adapted to at least partially receive a bearing or bushing (not shown) that mates with the eccentric shaft segment 302. A crankshaft oil hole 306 provides lubrication to the bearing or bushing. The counterweight 20 is specifically designed for the shape of the crankshaft 30 and requires precise positioning relative to the crankshaft 30. The counterweight 20 includes a joint 202. The joint 202 is annular or nearly annular, thereby engaging at least a portion of the eccentric shaft segment 302. The eccentric shaft segment 302 includes a first eccentric segment 303 and a second eccentric segment 304. Viewed axially, the cross-sectional area of ​​the second eccentric segment 304 is larger than the cross-sectional area of ​​the first eccentric segment 303. The first eccentric segment 303, as described above, guides the axial movement of the joint 202 under the action of the pressing force during the press-fitting process. After press-fitting, the second eccentric section 304 retains the joint 202 on the eccentric shaft section 302. The balance block 20 is press-fitted onto the eccentric shaft section 302, that is, the joint 202 is press-fitted onto the second eccentric section 304. The second eccentric section 304 limits the balance block 20 at least in the axial and radial directions.

[0043] During the press-fitting process, the axial and radial positions of the balance block 20 relative to the eccentric shaft section 302 are primarily determined by the fit between the joint 202 and the second eccentric section 304. However, the balance block 20 and the eccentric shaft section 302 also need to be accurately positioned circumferentially to avoid deviations between their actual and expected circumferential positions. Otherwise, it will still be difficult to balance the mass distribution of the eccentric shaft section 302 relative to the rotation axis R, and the generation of unbalanced centrifugal forces during crankshaft rotation cannot be avoided.

[0044] It should be noted that the term "axial" can refer to the direction parallel to the rotation axis R of the crankshaft 30. The term "circumferential" can refer to the two directions of rotation around the rotation axis R. Viewed along the axial direction of the pressing force, the clockwise circumferential direction is denoted as α. i The circumferential direction of the counterclockwise rotation is marked as α. j The term "radial" can refer to any direction that originates from a point on the axis of rotation R and extends in a plane perpendicular to the axis.

[0045] In view of this, a press-fit fixture is provided for precisely positioning the balance block 20 relative to the crankshaft 30, which is particularly capable of precisely positioning the balance block 20 relative to the crankshaft 30 in the circumferential direction. Figures 2 to 5 The pressing fixture of this utility model is shown in the embodiment. Figures 6 to 8 A schematic diagram of a mechanism including a press-fit fixture, a crankshaft, a balance block to be installed on the crankshaft, and an example of a mating component, according to an embodiment of the present invention, is shown. The following will be combined with... Figures 2 to 5 The specific structure of the press-fitting fixture is explained in detail, and combined with... Figures 6 to 8Explain the press-fit fixture and its connection with related components.

[0046] Figure 2 This is a three-dimensional structural diagram of the press-fit fixture according to an embodiment of this utility model. See also... Figure 2 The press-fit fixture 10 includes a fixture body 102. The fixture body 102 is cylindrical or nearly cylindrical, thereby enabling it to mate with the outer peripheral surface of the eccentric shaft segment 302 and avoiding interference with the balance block 20. Preferably, the fixture body 102 is not closed in the axial direction.

[0047] It should be noted that this utility model does not limit the fitting method between the fixture body 102 and the eccentric shaft section 302. For example, the fixture body 102 can be clearance-fitted with the eccentric shaft section 302, or only a cylindrical or near-cylindrical portion can fit with the eccentric shaft section 302. As long as the above fitting method satisfies the requirement that the press-fit fixture 10 is fitted onto the crankshaft 30 without interference, and that the press-fit fixture 10 is axially slidable relative to the crankshaft 30.

[0048] During the press-fitting process, at least a portion of the fixture body 102 can be accommodated in the gap 50. After press-fitting, the press-fitting fixture 10 is removed from the crankshaft 30 and the balance block 20 through the gap 50.

[0049] The fixture body 102 includes a bearing end face 104 and a pressing end face 106 disposed opposite each other in the axial direction. The bearing end face 104 is adapted to withstand the pressing force from the pressing equipment, and the pressing end face 106 is adapted to apply the pressing force to the counterweight 20. The bearing end face 104 and the pressing end face 106 transmit the pressing force, at least in the axial direction, to the joint 202, thereby pressing the joint 202 into the second eccentric section 304.

[0050] The pressure-bearing end face 104 and the pressure-applying end face 106 have axial lengths, and the axial lengths of the pressure-bearing end face 104 and the pressure-applying end face 106 constructed as described above shorten the axial stroke of the pressing equipment. This is beneficial for the design and operation of the pressing equipment.

[0051] It should be noted that the term "end face" is not intended to limit a face without thickness, but can refer to a surface or a part, or a single component, as long as they can have the same technical effect.

[0052] Figure 3 The pressing fixture of this utility model embodiment is along Figure 2 The sectional view taken by section line AA in the figure. See also Figure 3The inner circumferential side of the fixture body 102 also includes a protective sleeve or protective layer 112. During the press-fitting process, the press-fitting fixture 10 is fitted onto the crankshaft 30 and moves axially with the press-fitting force. The crankshaft 30 is made of a metal material, such as steel. The protective sleeve or protective layer 112 provided on the inner circumferential side of the fixture body can be made of a material with low hardness. Preferably, the hardness of the protective sleeve or protective layer 112 can be lower than the hardness of the fixture body 102. During the press-fitting process, the protective sleeve or protective layer 112 constructed as described above can prevent surface damage to the fixture body 102. In particular, it can also prevent surface damage to the crankshaft shaft surface that mates with the sliding bearing.

[0053] Preferably, the protective sleeve or protective layer 112 is at least partially made of aluminum or its alloy, copper or its alloy, nylon or Teflon.

[0054] The protective sleeve or protective layer 112 constructed as described above has low hardness. In particular, Teflon has self-lubricating properties, which helps reduce friction during the press-fitting process, thereby reducing the pressure required during press-fitting and further reducing the risk of crankshaft damage.

[0055] Figure 4 This is a front view of the press-fit fixture according to an embodiment of this utility model. See also... Figures 2 to 4 A first positioning part 108 is disposed on the fixture body 102. More specifically, the first positioning part 108 is configured to be axially adjacent to the pressure end face 106. The first positioning part 108 directly or indirectly cooperates with the crankshaft 30 to position the press-fit fixture 10 relative to the crankshaft 30 in the circumferential direction. It should be understood that the description "directly or indirectly cooperates" can mean that the first positioning part 108 can be positioned relative to the crankshaft 30 at least in the circumferential direction by its own structure or by means of other independent components. Optionally, the first positioning part 108 may be a slot, opening, or protrusion corresponding to the crankshaft oil hole 306, or it may be a part or component corresponding to other components (such as pin holes, cross slots, etc.) disposed on the eccentric shaft section 302.

[0056] Preferably, the first positioning part 108 is a through groove extending from the outer peripheral surface of the fixture body 102 to its inner peripheral surface, and the length direction of the through groove is substantially parallel to the axial direction. The through groove includes a first limiting surface 1081 and a second limiting surface 1082. The first limiting surface 1081 and the second limiting surface 1082 are arranged opposite to each other in the circumferential direction. The size of the through groove corresponds to the crankshaft oil hole 306. Preferably, the width of the through groove is equal to the inner diameter of the crankshaft oil hole 306, that is, the circumferential distance between the first limiting surface 1081 and the second limiting surface 1082 is equal to the inner diameter of the crankshaft oil hole 306.

[0057] Figure 5 This is a top view of the press-fit fixture according to an embodiment of this utility model. See also... Figure 2 , Figure 3 and Figure 5 The second positioning part 110 is disposed on the fixture body 102. More specifically, the second positioning part 110 is configured to be axially adjacent to the pressure-bearing end face 104. The second positioning part 110 directly or indirectly cooperates with the counterweight 20 to position the press-fit fixture 10 relative to the counterweight 20 in the circumferential direction. It should be understood that the description of "directly or indirectly cooperating" can mean that the second positioning part 110 can be positioned relative to the counterweight 20 at least in the circumferential direction by its own structure or by means of other independent components.

[0058] It should be understood that the shape of the second positioning part 110 is specifically designed to correspond to the shape of the balance block 20. If the balance block 20 has structures such as holes or slots, the second positioning part 110 can be set in a similar manner to the first positioning part 108, as long as the second positioning part can achieve the same technical effect.

[0059] Optionally, the second positioning part 110 is a snap-fit ​​assembly that engages with the stepped section of the balance block, a locking assembly that engages with the groove of the balance block, or a bolt and nut assembly that passes through the hole of the balance block 20.

[0060] Preferably, the second positioning portion 110 comprises two protruding lugs extending outward from the outer periphery of the fixture body 102. The two lugs are spaced apart circumferentially. That is, when viewed in a direction parallel to the axial direction, the two lugs are at an angle. Optionally, the angle β between the two lugs can be between 90° and 180°, between 120° and 180°, or equal to 180°. The lug-shaped second positioning portion 110 constructed as described above facilitates demolding and can be precisely positioned circumferentially corresponding to the angled balance block 20.

[0061] Figure 6 This is an exploded structural diagram of the press-fitting mechanism, which includes a crankshaft, a balance block to be installed on the crankshaft, a press-fitting fixture and a positioning pin according to an embodiment of the present invention. Figure 7A yes Figure 6 A schematic diagram of the pressing mechanism. Figure 7B yes Figure 6 A sectional view of the pressing mechanism along the BB section line. See also Figures 6 to 7B The first positioning part 108, which forms a through groove, engages with the crankshaft oil hole 306 via a positioning pin 40, thereby achieving circumferential positioning of the crankshaft 30 and the press-fit fixture 10. The positioning pin 40 passes through the through groove and the crankshaft oil hole 306 in sequence. When the pressing force of the press-fitting equipment is applied to the pressing end face 104, the press-fit fixture 10 moves continuously in the axial direction. The first limiting surface 1081 of the through groove contacts the outer surface of the positioning pin 40, thereby limiting the press-fit fixture 10 relative to the crankshaft 30 in α. jRotation in the direction. The second limiting surface 1082 of the through groove contacts the outer surface of the locating pin 40, thereby limiting the press-fit fixture 10 relative to the crankshaft 30 in α. i Rotating in the direction. In this way, the first positioning part 108 ensures the precise circumferential positioning of the press-fit fixture 10 relative to the crankshaft 30.

[0062] Figure 8 yes Figure 6 A top view of the press-fitting mechanism. See also... Figure 8 Preferably, one end of the positioning pin 40 extends beyond the outer peripheral surface of the fixture body 102. The positioning pin 40 constructed in the above manner not only facilitates the positioning and installation of the press-fit fixture 10, but also makes it easier to monitor the circumferential position of the press-fit fixture 10 during the press-fitting process.

[0063] The locating pin 40 can be a separate component such as a conical locating pin or a spherical locating pin, or other locating components such as bolts and nuts used together, as long as they can achieve precise circumferential positioning of the press-fit fixture 10 relative to the crankshaft 30 through the first locating part 108 with a through groove.

[0064] By way of example only, the first positioning portion 108, which forms a through groove, may also include an upper limit portion 1083. As the press-fit fixture 10 moves axially under the action of the press-fitting force, the upper limit portion 1083 gradually approaches the positioning pin 40. After press-fitting is completed, the upper limit portion 1083 is spaced apart from the positioning pin 40. Optionally, the upper limit portion 1083 may eventually contact the outer surface of the positioning pin 40 to define a minimum axial level of the press-fitting fixture 10 during the press-fitting process. The upper limit portion 1083 helps limit the axial press-fitting stroke of the press-fitting equipment. When the axial movement of the press-fitting equipment exceeds a predetermined value, the upper limit portion 1083 blocks the counterweight 20 and provides feedback to prevent the counterweight 20 from moving axially beyond the second eccentric section 304, thus avoiding damage to components such as the crankshaft 30.

[0065] Optionally, the first positioning portion 108, which forms a through groove, includes an opening 1084. The upper limit portion 1083 is disposed opposite to the opening 1084 in the axial direction. The first positioning portion 108, which forms a through groove, extends axially to the pressure end face 106, and the opening 1084 is formed on the pressure end face 106.

[0066] Advantageously, the opening 1084 simplifies the installation of the press-fit fixture 10. Before press-fitting, the locating pin 40 can be fitted onto the crankshaft oil hole 306. Subsequently, the press-fit fixture 10 is axially fitted onto the crankshaft 30 through the gap 50, and the locating pin 40 directly enters the first positioning part 108, which forms a through groove, through the opening 1084. If the opening 1084 is not provided, before press-fitting, the press-fit fixture 10 must first be axially fitted onto the crankshaft 30 through the gap 50, then visually aligned with the first positioning part 108 and the crankshaft oil hole 306, and then the locating pin 40 is inserted, so that the locating pin 40 passes through the through groove and the crankshaft oil hole 306 in sequence. For through grooves without the opening 1084, accurate alignment and insertion of the locating pin 40 is more difficult.

[0067] See Figure 5 , Figure 7B and Figure 8 Two protruding lugs extending outward from the fixture body 102 form a space 60 in the area covered by angle β. During the press-fitting process, the space 60 can accommodate at least a portion of the balance block 20.

[0068] Each of the two lugs in the above-described structure includes a positioning surface 1101 and a non-positioning surface 1102. The two positioning surfaces 1101 of the two lugs are adjacent in the circumferential direction. That is, at least a portion of the two positioning surfaces 1101 are accommodated in the space 60, while the two non-positioning surfaces 1102 are not accommodated in the space 60.

[0069] It should be noted that the description "the two positioning surfaces 1101 of the two lugs are adjacent in the circumferential direction" means that, in the circumferential direction, the distance from the positioning surface 1101 of one lug housed in the space 60 to the positioning surface 1101 of the other lug is less than the distance from the positioning surface 1101 of one lug housed in the space 60 to the non-positioning surface 1102 of the other lug. For the same lug, although the distance from the positioning surface 1101 to the non-positioning surface 1102 in the circumferential direction may be less than the distance from the positioning surface 1101 of one lug housed in the space 60 to the positioning surface 1101 of the other lug, this does not contradict the "adjacent" meaning in the above description.

[0070] See Figure 6The balance block 20 includes a positioned surface 201 that abuts against the positioning surface 1101 of the lug. Before press-fitting, the balance block 20 is placed on the crankshaft 30, and then the press-fitting fixture 10 is fitted onto the crankshaft 30, with at least a portion of each of the two positioned surfaces 201 of the balance block 20 being accommodated in the space 60. During press-fitting, the press-fitting force of the press-fitting equipment is applied to the pressing end face 106, and the press-fitting fixture 10 moves continuously in the axial direction. A portion of the positioning surface 1101 in the space 60 abuts against a portion of the positioned surface 201 of the balance block 20, thereby forming two spaced-apart contact points in the circumferential direction. One of the two contact points restricts the balance block 20 relative to the press-fitting fixture 10 at α i Rotating in the direction, the other limiting balance block of the two contact points is relative to the press-fit fixture 10 at α j Rotate in the direction. In this way, the second positioning part 110 ensures the precise circumferential positioning of the balance block 20 relative to the press-fit fixture 10.

[0071] It should be noted that the term "contact point" is not intended to limit a point in one dimension, but can specify the surface, part or component formed by the contact between the plane 1101 and the positioned surface 201, as long as they can have the same technical effect.

[0072] The balance block 20 is precisely positioned circumferentially relative to the press-fit fixture 10 via the second positioning part 110, while the press-fit fixture 10 is precisely positioned circumferentially relative to the crankshaft 30 via the first positioning part 108. Therefore, the positions of the balance block 20 and the crankshaft 30 are precisely defined, at least circumferentially.

[0073] See Figure 6 The first positioning part 108 is disposed circumferentially between the two non-positioning surfaces 1102 of the two lugs and spaced apart from the two non-positioning surfaces 1102. That is, the first positioning part 108 is located outside the space 60 that accommodates at least a portion of the balance block 20. The first positioning part 108 disposed in this way can avoid interference with the balance block 20, thereby facilitating the installation and use of the press-fit fixture.

[0074] See Figure 8 The reference line l1 passing through the axis of the first positioning part 108 and the fixture body 102, which are in the form of a through groove, is substantially perpendicular to the reference plane P1 where the two positioning surfaces 1101 are located.

[0075] See Figure 5 and Figure 8The press-fit fixture 10 further includes a first arc transition portion 114 and a second arc transition portion 116. The first arc transition portion 114 is located at the junction of the positioning surface 1101 of each second positioning portion 110 and the outer peripheral surface of the fixture body 102. The second arc transition portion 116 is located at the junction of the non-positioning surface 1102 of each second positioning portion 110 and the outer peripheral surface of the fixture body 102. Optionally, the radius of the first arc transition portion 114 is smaller than the radius of the second arc transition portion 116.

[0076] The smaller radius of the first arc transition portion 114 increases the area of ​​the positioning surface 1101 accommodated in the space 60, thereby enhancing the area of ​​the contact point. The two contact points respectively limit the balance block 20 relative to the press-fit fixture 10 at α... j / α i The larger the contact area, the higher the stability of the balancing block 20 relative to the press-fit fixture 10 in circumferential rotation, making the positioning between the press-fit fixture and the balancing block more precise and stable. The second arc transition portion 116 has a larger radius, which achieves a smooth connection between the non-positioning surface 1102 and the outer peripheral surface of the fixture body 102, avoiding the mechanical risks that sharp structures may bring, and increasing the strength of the press-fit fixture 10.

[0077] Preferably, the press-fit fixture 10 with the above-described structure is integrally formed.

[0078] The scope of protection of this utility model is not limited to the above embodiments. Any variations or substitutions that can be conceived by those skilled in the art within the scope of the technology disclosed herein should be included within the scope of protection of this utility model. Therefore, the scope of protection of this utility model should be determined by the scope of the claims.

Claims

1. A press-fitting fixture, characterized in that, The press-fit fixture is used to press the balance weights onto the crankshaft and includes: The fixture body is cylindrical or partially cylindrical to be slidably fitted onto the crankshaft relative to it in the axial direction, and includes a bearing end face and a pressing end face opposite in the axial direction, the bearing end face being adapted to withstand a pressing force from a pressing device, and the pressing end face being adapted to apply the pressing force to the balance block; A first positioning part, disposed on the main body of the fixture, and adapted to directly or indirectly cooperate with the crankshaft to position the press-fit fixture relative to the crankshaft in the circumferential direction; and The second positioning part is disposed on the main body of the fixture and is adapted to cooperate directly or indirectly with the balance block to position the press-fit fixture relative to the balance block in the circumferential direction.

2. The press-fit fixture according to claim 1, characterized in that, The first positioning part is a through groove, which extends from the outer peripheral surface of the fixture body to its inner peripheral surface to penetrate the fixture body, and the length direction of the through groove is substantially parallel to the axial direction.

3. The press-fitting fixture according to claim 2, characterized in that, The through groove extends along the axial direction to the pressure-applying end face to form an opening on the pressure-applying end face.

4. The press-fitting fixture according to claim 1, characterized in that, The second positioning part is a protruding lug that extends outward from the outer periphery of the fixture body.

5. The press-fitting fixture according to claim 4, characterized in that, The lugs are two lugs spaced apart along the circumferential direction. Each lug has a positioning surface on one side along the circumferential direction. The positioning surface is adapted to abut against the positioning surface of the balance block to position the press fixture relative to the balance block along the circumferential direction. The two positioning surfaces of the two lugs are adjacent in the circumferential direction.

6. The press-fitting fixture according to claim 5, characterized in that, The two positioning surfaces are coplanar. The first positioning part is a through groove. The through groove extends from the outer peripheral side of the fixture body to its inner peripheral surface to penetrate the fixture body. The length direction of the through groove is basically parallel to the axial direction. The reference straight line passing through the through groove and the axis of the fixture body is basically perpendicular to the reference plane where the two positioning surfaces are located.

7. The press-fitting fixture according to claim 5, characterized in that, Each lug has a non-positioning surface that is opposite to the positioning surface along the circumferential direction, and the first positioning part is located between the two non-positioning surfaces of the two lugs in the circumferential direction and is spaced apart from the two non-positioning surfaces.

8. The press-fit fixture according to claim 7, characterized in that, The press-fit fixture further includes a first arc transition portion and a second arc transition portion. The first arc transition portion is located at the junction of the positioning surface and the fixture body, and the second arc transition portion is located at the junction of the non-positioning surface and the fixture body. The radius of the first arc transition portion is smaller than the radius of the second arc transition portion.

9. The press-fitting fixture according to claim 1, characterized in that, The inner circumference of the fixture body is provided with a protective sleeve or protective layer, and the hardness of the protective sleeve or protective layer is lower than the hardness of the fixture body.

10. The press-fit fixture according to claim 9, characterized in that, The protective sleeve or the protective layer is made at least in part of aluminum or its alloy, copper or its alloy, nylon or Teflon.

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