Spline connection device

Abstract

To provide a spline connection device capable of mitigating stress on an axial base end side in internal and external spline teeth.SOLUTION: A hub 32 is provided with an internal spline part 32C on an inner circumferential side. A rotary shaft 34 is provided with an external spline part 34A on an outer circumferential side. A clamping screw 35 restrains internal spline teeth 32C1 and external spline teeth 34A1 by pressing a thin wall part 32H. The external spline teeth 34A1 and the internal spline teeth 32C1 respectively have tapered surfaces 43 and 52 at ends 42 and 53 on an axial base end side. In a circumferential view, the tapered surfaces 43 of the external spline teeth 34A1 and the tapered surfaces 52 of the internal spline teeth 32C1 intersect in a state in which the internal spline part 32C and the external spline part 34A are spline-connected.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a spline coupling device that transmits rotational force between a prime mover and a hydraulic pump mounted on a construction machine such as a hydraulic excavator. [Background technology]

[0002] For example, a spline coupling device is used to connect the prime mover and hydraulic pump of a construction machine such as a hydraulic excavator so as to enable the transmission of rotational force. The spline coupling device includes, for example, a cylindrical hub having a splined hole on its inner periphery, and a rotating shaft having a splined shaft on its outer periphery that is splined to the splined hole of the hub.

[0003] Furthermore, for example, Patent Document 1 discloses a coupling in which a hole spline portion of a hub and a shaft spline portion are constrained by pressing the hole spline teeth of the hole spline portion of the hub against the shaft spline teeth of the shaft spline portion of a rotating shaft with a screw. Furthermore, Patent Document 2 discloses a spline coupling structure in which a notch is provided on the base end side of the spline teeth extending in the axial direction, which is opposite to the tip side in the axial direction of the rotating shaft. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 53-73342 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-250356 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when the axial length of the axial spline teeth is shorter than the axial length of the bore spline teeth, the axial end portions of the axial spline teeth, i.e., the inclined portions (end portions having tapered surfaces) of the axial spline teeth that rise radially outward come into circumferential contact with the side surfaces of the axially intermediate portions of the bore spline teeth. Conversely, when the axial length of the axial spline teeth is shorter than the axial length of the axial spline teeth, the axial end portions of the bore spline teeth, i.e., the inclined portions (end portions having tapered surfaces) of the axial spline teeth that rise radially inward come into circumferential contact with the side surfaces of the axially intermediate portions of the axial spline teeth.

[0006] Here, the axial end portions (end portions having inclined portions or tapered surfaces) of the axial spline teeth or the bore spline teeth have lower rigidity than the counterparts with which these end portions abut in the circumferential direction, i.e., the axial intermediate portions of the bore spline teeth or the axial spline teeth. Therefore, when transmitting rotational force, the amount of deformation due to bending of the axial end portions (end portions having inclined portions or tapered surfaces) of the spline teeth tends to increase, and stress may concentrate at the circumferential abutment portion between the end portions and the intermediate portion of the counterpart.

[0007] In particular, the axial spline teeth provided on the rotating shaft have relief grooves for a machining tool used to form these axial spline teeth on the base end side, which is opposite the axial tip side of the rotating shaft. Therefore, if left as is, the axial length of the axial spline teeth will be shorter than the bore spline teeth, and the base end side of the axial spline teeth and the axial middle part of the bore spline teeth will abut in the circumferential direction. As a result, when transmitting rotational force, the amount of deformation due to bending of the base end side of the axial spline teeth (the end having the inclined portion or tapered surface) tends to increase, and stress may concentrate at the circumferential abutment part between this end and the middle part of the bore spline portion.

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide a spline connecting device capable of alleviating stress on the base end side in the axial direction of the hole spline teeth and the shaft spline teeth. [Means for solving the problem]

[0009] The present invention preferably provides a rotary shaft including a cylindrical hub having a hole spline portion on its inner periphery, and a shaft spline portion at its tip end which is provided on the outer periphery thereof and which is splined to the hole spline portion, the hub having a through hole provided radially outside the hole spline portion and penetrating in the axial direction of the hub from one end face to the other end face, an insertion hole formed from the outer circumferential side surface of the hub toward the through hole, and a thin-walled portion formed between the through hole of the hub and the hole spline portion, and a rotary shaft inserted into the insertion hole of the hub and pressing the thin-walled portion. and a pressing tool for pressing the axial spline portion against the rotation shaft in the axial direction of the rotation shaft, the axial spline portion has a axial spline tapered surface formed at a base end side end opposite to the tip end side of the axial spline teeth, and the hole spline portion has a hole spline tapered surface formed at a base end side end of the hole spline teeth in the axial direction, and the axial spline tapered surface and the hole spline tapered surface are formed so as to intersect when viewed from the circumferential direction of the hub in a state where the hole spline portion and the axial spline portion are spline-coupled. [Effects of the Invention]

[0010] According to the present invention, stress on the base end side in the axial direction of the hole spline teeth and the shaft spline teeth can be alleviated. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a left side view showing a construction machine (hydraulic excavator) to which a spline connector according to an embodiment is applied. [Figure 2] FIG. 2 is an enlarged cross-sectional view taken along the direction of arrows II-II in FIG. [Figure 3] This is an enlarged cross-sectional view of the engine, shaft coupling, hydraulic pump, etc., taken from the same direction as in FIG. 2. [Figure 4] FIG. 2 is an exploded perspective view showing a flywheel, a shaft coupling, a hydraulic pump, etc. [Figure 5] FIG. 2 is an exploded perspective view showing an enlarged view of a rotary shaft, a hub, and a pump-side block. [Figure 6]FIG. 2 is a cross-sectional view showing a rotating shaft, a hub, and a pressing tool (clamping screw). [Figure 7] FIG. 7 is an enlarged cross-sectional view showing part (VII) in FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. 4 is a cross-sectional view showing the hub and the pressing tool. [Figure 12] FIG. [Figure 13] FIG. 13 is a perspective view of the hub and the pressing tool as viewed from the right side of FIG. 12. [Figure 14] 8A is a cross-sectional view taken at the same position as in FIG. 7, showing a reference example (A), an embodiment (B), and a modification (C). DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a spline connector according to an embodiment will be described in detail with reference to the accompanying drawings, taking as an example a case where the spline connector is applied to a connection (spline connection) between an engine and a hydraulic pump mounted on a hydraulic excavator.

[0013] In Fig. 1, a hydraulic excavator 1, which is a representative example of construction machinery, includes a self-propelled crawler-type lower traveling body 2, an upper rotating body 3 rotatably mounted on the lower traveling body 2, and a working device 4 attached to the front side of the upper rotating body 3. The lower traveling body 2 and the upper rotating body 3 form the vehicle body of the hydraulic excavator 1. The hydraulic excavator 1 performs work such as excavating earth and sand using the working device 4.

[0014] A hydraulic traveling motor (not shown) is provided on the lower traveling body 2. The lower traveling body 2 travels by the hydraulic traveling motor. A hydraulic swing motor (not shown) is provided on the upper rotating body 3. The upper rotating body 3 swings by the hydraulic swing motor.

[0015] The work implement 4, also called the front implement, includes a boom 4A, an arm 4B, and a bucket 4C as a work implement. The work implement 4 also includes a boom cylinder 4D that drives the boom 4A, an arm cylinder 4E that drives the arm 4B, and a bucket cylinder 4F that drives the bucket 4C as a work implement cylinder.

[0016] The revolving frame 5 constitutes a support structure (support frame, vehicle body frame) for the upper revolving body 3. The revolving frame 5 is mounted so as to be able to revolve on the lower traveling body 2. The revolving frame 5 is mounted with a cab 6, a counterweight 7, an engine 9, a hydraulic pump 15, a heat exchanger 23, etc.

[0017] The swivel frame 5 comprises a bottom plate 5A made of a thick steel plate or the like extending in the fore-and-aft direction, a left vertical plate 5B and a right vertical plate 5C standing on the bottom plate 5A and extending in the fore-and-aft direction, a left side frame 5D located outside the left vertical plate 5B and extending in the fore-and-aft direction, a right side frame 5E located outside the right vertical plate 5C and extending in the fore-and-aft direction, a left overhang beam 5F connecting the bottom plate 5A and the left vertical plate 5B with the left side frame 5D, and a right overhang beam 5G connecting the bottom plate 5A and the right vertical plate 5C with the right side frame 5E.

[0018] As shown in Fig. 1, the working device 4 (the boom 4A and the boom cylinder 4D) is rotatably attached to the front sides of the left vertical plate 5B and the right vertical plate 5C. As shown in Fig. 2, at the rear side of the revolving frame 5, for example, mounting bases 5H are provided spaced apart in the front-to-rear direction, positioned between the left vertical plate 5B and the right vertical plate 5C and extending upward. An engine 9 is attached to each mounting base 5H in a vibration-damped state via vibration-damping mounts 24.

[0019] As shown in Figure 1, the cab 6 is mounted on the left front side of the revolving frame 5. The cab 6 forms a cab where the operator sits. Inside the cab 6, the operator's seat, operating levers for traveling and operating levers operated by the operator, etc. are arranged.

[0020] The counterweight 7 is attached to the rear ends of the left vertical plate 5B and the right vertical plate 5C of the revolving frame 5. The counterweight 7 is formed in a roughly arc shape and is a heavy object that balances the weight with the work implement 4. The exterior cover 8 is located between the cab 6 and the counterweight 7 and is provided on the revolving frame 5. The exterior cover 8 is composed of an engine cover 8A, a left cover 8B, and a right cover 8C. The exterior cover 8 houses onboard equipment such as the engine 9, hydraulic pump 15, and heat exchanger 23.

[0021] The engine 9 serving as a prime mover is located in front of the counterweight 7 and is provided on the rear end side of the revolving frame 5. The engine 9 is configured, for example, as a diesel engine. The engine 9 is mounted on the upper revolving body 3 in a horizontally placed state with the central axis of the crankshaft 11 serving as the output shaft extending in the left-right direction. Exhaust gas from the engine 9 is discharged via an exhaust gas aftertreatment device 25. Note that the prime mover of the hydraulic excavator 1 may be a hybrid prime mover that combines a diesel engine and an electric motor, or a prime mover that is a single electric motor.

[0022] As shown in Figures 2 and 3, the engine 9 includes an engine body 10, a plurality of (e.g., six) cylinders (not shown) provided in the engine body 10, a plurality of (e.g., six) pistons (not shown) that reciprocate within each cylinder, and a crankshaft 11 (hereinafter referred to as output shaft 11) that is connected to each piston via a connecting rod (not shown) and outputs the reciprocating motion of each piston as rotational force.

[0023] The engine body 10 includes a crankcase 10A formed as a hollow container that houses the output shaft 11, an oil pan 10B provided below the crankcase 10A and that houses engine oil, a cylinder block 10C mounted on the crankcase 10A and having a cylinder formed therein, and a cylinder head 10D mounted on the cylinder block 10C.

[0024] As shown in FIG. 2, a cooling fan 12 for supplying cooling air to a heat exchanger 23 is provided at one end side (left side in FIG. 2) of the engine body 10. A water jacket (not shown) through which engine coolant circulates is formed in a cylinder block 10C and a cylinder head 10D of the engine body 10. The water jacket is connected to a heat exchanger 23 that releases heat from the coolant. The heat exchanger 23 cools the engine coolant and the like.

[0025] As shown in Fig. 3, a disk-shaped flywheel 13 is provided on the other end (right side in Fig. 3) of the output shaft 11, at an end that protrudes into the flywheel housing 14. As shown in Fig. 4, the flywheel 13 has four female threaded holes 13A formed at equal intervals in the circumferential direction at four positions on an arc centered on the center of rotation. Bolts 19 for attaching a prime mover-side block 18 of the shaft coupling 17 are threadedly engaged into each of these female threaded holes 13A.

[0026] As shown in Figures 2 and 3, a short, cylindrical flywheel housing 14 is provided at the other end (right side in Figures 2 and 3) of the engine body 10. A flywheel 13 and a shaft coupling 17 having an elastic body 20 made of resin or the like are disposed within the flywheel housing 14. An open end of the flywheel housing 14 forms a flange mounting portion 14A to which a flange portion 15B of the hydraulic pump 15 is attached. A plurality of female threaded holes 14B are arranged in a circumferential direction in the flange mounting portion 14A. Bolts 16 for attaching the flange portion 15B of the hydraulic pump 15 to the flange mounting portion 14A are threadedly engaged into the female threaded holes 14B.

[0027] The hydraulic pump 15 is rotationally driven by the engine 9. The hydraulic pump 15 is attached to the engine 9 via a flywheel housing 14. Driven by the engine 9, the hydraulic pump 15 discharges hydraulic oil for operation toward various hydraulic actuators (such as a traveling hydraulic motor, a swing hydraulic motor, a boom cylinder 4D, an arm cylinder 4E, and a bucket cylinder 4F) mounted on the hydraulic excavator 1. The hydraulic pump 15 includes a pump mechanism (not shown) constituted by, for example, a bent-axis hydraulic pump or a swash plate hydraulic pump, a pump casing 15A that houses the pump mechanism, and a rotary shaft 34 that protrudes from the center of the pump casing 15A and is connected to the pump mechanism.

[0028] Meanwhile, the base end side (left side in FIGS. 2 and 3) of the pump casing 15A forms an annular flange portion 15B that expands radially outward over the entire periphery. The flange portion 15B serves as a mounting plate for mounting the hydraulic pump 15 to the engine 9. That is, the flange portion 15B is mounted to (the flange mounting portion 14A of) the flywheel housing 14 using bolts 16. For this purpose, the flange portion 15B is provided with bolt insertion holes 15C at positions corresponding to the female thread holes 14B of the flange mounting portion 14A of the flywheel housing 14.

[0029] Next, the shaft coupling 17 that connects the output shaft 11 of the engine 9 and the rotary shaft 34 of the hydraulic pump 15 will be described.

[0030] The shaft coupling 17 is provided between the output shaft 11 of the engine 9 (more specifically, the flywheel 13 provided on the output shaft 11) and the rotating shaft 34 of the hydraulic pump 15. The shaft coupling 17 absorbs torque fluctuations, misalignment of the central axis of rotation, etc. between the output shaft 11 (flywheel 13) of the engine 9 and the rotating shaft 34 of the hydraulic pump 15 based on elastic deformation of the elastic body 20. The shaft coupling 17 is disposed (housed) inside the flywheel housing 14 (shaft coupling chamber) so as to be adjacent to the flywheel 13 in the axial direction. The shaft coupling 17 includes a plurality (four) of prime mover-side blocks 18 (hereinafter referred to as engine-side blocks 18), an elastic body 20, a plurality (four) of driven-side blocks 21 (hereinafter referred to as pump-side blocks 21), and a hub 32.

[0031] The four engine-side blocks 18 are attached at intervals in the circumferential direction (rotational direction) to the flywheel 13, which is on the output shaft 11 side of the engine 9. Each engine-side block 18 is formed as a roughly fan-shaped block body and has a bolt insertion hole 18A extending in the axial direction. Each engine-side block 18 is integrally attached to the side of the flywheel 13 by threading a bolt 19 inserted into the bolt insertion hole 18A into an internally threaded hole 13A of the flywheel 13.

[0032] The engine-side block 18 is provided with flanges 18B located on the outer diameter side and extending in the circumferential direction on both circumferential sides. These flanges 18B, together with the flange 21B of the pump-side block 21, restrict radial displacement of the elastic body 20. That is, the flanges 18B of the engine-side block 18 and the flanges 21B of the pump-side block 21 abut against the outer peripheral surfaces of the elastic body 20, preventing the elastic body 20 from further displacing radially outward.

[0033] Elastic body 20 is formed into a thick cylindrical shape using, for example, an elastic resin material or rubber material, and is disposed so as to surround hub 32. In elastic body 20, prime mover-side block engaging grooves 20B (hereinafter referred to as engine-side block engaging grooves 20B) that accommodate engine-side block 18 and driven-side block engaging grooves 20C (hereinafter referred to as pump-side block engaging grooves 20C) that accommodate pump-side block 21 are formed alternately in the circumferential direction from outer circumferential surface 20A thereof toward the radially inward direction.

[0034] That is, the elastic body 20 has a hub receiving portion 20D in the center in which the hub 32 is received. Four engine-side block engaging grooves 20B and four pump-side block engaging grooves 20C are alternately arranged at intervals in the circumferential direction around the hub receiving portion 20D. Between each engine-side block engaging groove 20B and each pump-side block engaging groove 20C, a compression portion 20E is formed, which is compressed (sandwiched) in the circumferential direction by the engine-side block 18 and the pump-side block 21, respectively.

[0035] The four pump-side blocks 21 are attached to the outer periphery of the hub 32 at intervals in the circumferential direction, protruding radially outward from the hub 32. Each pump-side block 21 is formed as a generally fan-shaped block body. Each pump-side block 21 has a bolt insertion hole 21A extending radially. Each pump-side block 21 is integrally attached to the outer circumferential side surface 32D of the hub 32 by threading a bolt 22 ( FIG. 3 ) inserted into the bolt insertion hole 21A into a threaded hole (not shown) in the hub 32. Each pump-side block 21 is provided with flanges 21B located on the outer diameter side and extending in the circumferential direction on both sides in the circumferential direction. Similar to the flange 18B of the engine-side block 18, each flange 21B restricts radial displacement of the elastic body 20.

[0036] Next, the spline coupling device 31 including the rotary shaft 34 of the hydraulic pump 15 and the hub 32 of the shaft coupling 17 will be described.

[0037] The spline coupling device 31 transmits rotational force between the engine 9 and the hydraulic pump 15. The spline coupling device 31 includes a hub 32 of the shaft coupling 17, a rotating shaft 34 of the hydraulic pump 15, and a clamping screw 35 as a pressing tool.

[0038] The hub 32 is formed as a thick-walled cylindrical body. The hub 32 is accommodated in the hub accommodating portion 20D of the elastic body 20. The hub 32, together with the rotary shaft 34, constitutes the spline coupling device 31. The hub 32 corresponds to a driving member that rotationally drives the rotary shaft 34 using the rotational force from the engine 9. A bore spline portion 32C is provided on the inner peripheral side of the hub 32. The bore spline portion 32C is provided between one side surface 32A and the other side surface 32B of the hub 32, that is, between the one side surface 32A that is the side surface on the hydraulic pump 15 side (the base end side of the rotary shaft 34 in the axial direction) and the other side surface 32B that is the side surface on the engine 9 side (the tip end side of the rotary shaft 34 in the axial direction). The bore spline portion 32C is configured as an involute spline having a plurality of bore spline teeth 32C1 extending in the axial direction. The bore spline portion 32C is spline-coupled to the shaft spline portion 34A of the rotary shaft 34.

[0039] Meanwhile, screw holes (not shown) for attaching the pump side block 21 are provided in four circumferential positions (for example, at equal 90° intervals) on the outer peripheral side surface 32D of the hub 32. The pump side block 21 is fixed to the hub 32 using bolts 22 (FIG. 3) that are inserted into bolt insertion holes 21A of the pump side block 21 and screwed into screw holes in the hub 32. The hub 32 also has an insertion hole 32F for inserting a pressing tool at a position that does not interfere with the screw holes.

[0040] The insertion holes 32F are drilled from the outer peripheral side surface 32D of the hub 32 toward the radially inward direction (toward the hole spline portion 32C). That is, the central axis O2-O2 of each insertion hole 32F (see FIGS. 10 and 11) extends in a direction perpendicular to the central axis O1-O1 of the hub 32 (hole spline portion 32C) (see FIGS. 10 and 11). In other words, the insertion holes 32F are bottomed holes extending radially of the hub 32. Two insertion holes 32F are provided between adjacent threaded holes in the circumferential direction, and are spaced apart in the axial direction of the hub 32. The inner diameter portions 32F1 of the insertion holes 32F are connected by a glasses-shaped (gourd-shaped) through hole 32G extending in the axial direction of the hub 32. The insertion holes 32F are formed as female threaded holes. A clamping screw 35 is threaded into the insertion holes 32F.

[0041] A glasses-shaped (gourd-shaped) through-hole 32G is provided between the hole spline portion 32C and the insertion hole 32F. The through-hole 32G penetrates between the one side surface 32A and the other side surface 32B and communicates with the inner diameter portion 32F1 of each insertion hole 32F. As shown in FIG. 10 , the through-hole 32G has a narrow width portion 32G1 at a position where it intersects with an imaginary plane including the central axis O1-O1 of the hole spline portion 32C and the central axis O2-O2 of the insertion hole 32F. The through-hole 32G has circular portions 32G2 on both sides of the narrow width portion 32G1. The narrow width portion 32G1 communicates the pair of circular portions 32G2 between the pair of circular portions 32G2.

[0042] A thin-walled portion 32H is formed between the insertion hole 32F and the hole spline portion 32C. That is, the thin-walled portion 32H is formed between the inner diameter side of the narrow portion 32G1 of the through hole 32G and the hole spline portion 32C. The inner diameter side of the narrow portion 32G1 is flat, and the tip surface of the clamping screw 35 abuts against it, and is pressed by the tip surface of the clamping screw 35. The periphery of the thin-walled portion 32H is easily deformed due to the formation of the through hole 32G.

[0043] Therefore, the hole spline teeth 32C1 and the axial spline teeth 34A1 can be constrained with a small force when the thin-walled portion 32H is pressed by the clamping screw 35. Moreover, since the through-hole 32G also makes it easier for the periphery of the circular portion 32G2 to deform, when the thin-walled portion 32H is pressed by the clamping screw 35, the hole spline teeth 32C1 and the axial spline teeth 34A1 can be constrained with an even smaller force.

[0044] The rotating shaft 34 of the hydraulic pump 15 is formed as a solid cylindrical body. The rotating shaft 34 is a driven member (driven shaft) that is rotationally driven by the rotational force from the engine 9 via the hub 32 of the shaft coupling 17. For this purpose, an axial spline portion 34A is provided on the outer periphery of the rotating shaft 34, which is spline-coupled to a hole spline portion 32C of the hub 32 of the shaft coupling 17. The axial spline portion 34A is configured as an involute spline having a plurality of axial spline teeth 34A1 extending in the axial direction. The rotating shaft 34, together with the hub 32, constitutes the spline coupling device 31.

[0045] A clamping screw 35 serving as a pressing tool is inserted into the insertion hole 32F of the hub 32. The clamping screw 35 presses the thin-walled portion 32H (applies a force in a direction that widens the narrow width portion 32G1) based on the tightening (screw engagement) of the clamping screw 35 into the insertion hole 32F. This constrains the hole spline teeth 32C1 of the hole spline portion 32C and the axial spline teeth 34A1 of the axial spline portion 34A. In this case, the hub 32 is deformed based on the clamping screw 35 pressing the thin-walled portion 32H, and the hole spline teeth 32C1 widen. This allows the hole spline teeth 32C1 and the axial spline teeth 34A1 to be constrained.

[0046] The axial spline teeth provided on the rotary shaft have a small-diameter portion on the base end, opposite the axial tip end, of the rotary shaft, having an outer diameter smaller than the outer diameter of the rotary shaft. This small-diameter portion functions as an escape groove for a machining tool used to form the axial spline teeth. Specifically, as shown in FIGS. 8 and 9, a groove 41 is formed around the entire circumference of the rotary shaft 34 at a position on the base end side (left side in FIGS. 8 and 9) of the axial spline teeth 34A1. The groove 41 serves as an escape groove for escaping the machining tool when machining the axial spline teeth 34A1 (hereinafter, the groove 41 will be referred to as the "escape groove 41"). Therefore, if left as is, the axial length of the axial spline teeth 34A1 will be shorter than the bore spline teeth 32C1, as in the reference example shown in FIG. 14(A). In this case, the end 42 (the end 42 having the tapered surface 43) on the axial base end side of the axial spline tooth 34A1 circumferentially abuts against the side surface of the axial intermediate portion 51 of the hole spline tooth 32C1.

[0047] However, the end 42 on the base end side in the axial direction of the axial spline tooth 34A1 (the end 42 having the tapered surface 43) has lower rigidity than the counterpart with which the end 42 abuts in the circumferential direction, i.e., the axial intermediate portion 51 of the bore spline tooth 32C1. Therefore, when transmitting a rotational force, the amount of deformation due to bending of the end 42 on the base end side in the axial direction of the axial spline tooth 34A1 (the end 42 having the tapered surface 43) tends to increase, and stress may be concentrated at the circumferential abutment portion between the end 42 and the intermediate portion 51 of the bore spline tooth 32C1.

[0048] Therefore, as shown in Figures 14B and 14C, in the embodiment and modified example, the tapered surfaces 43 of the axial spline teeth 34A1 and the tapered surfaces 52 of the hole spline teeth 32C1 intersect when viewed from the circumferential direction when the hole spline portion 32C and the axial spline portion 34A are spline-coupled. This allows the axial base ends 42, 53 of the axial spline teeth 34A1 and the axial base ends of the hole spline teeth 32C1 to abut in the circumferential direction, with the ends 42, 53 having the tapered surfaces 43, 52, respectively, i.e., the ends 42, 53 having the same rigidity. This allows the amounts of deformation due to bending at the abutting portions to be equal, and stresses to be uniformly distributed, thereby reducing stress concentration. These points will be described in detail below.

[0049] As shown in FIGS. 6 to 13, the spline coupling device 31 includes a hub 32, a rotating shaft 34, and a clamping screw 35 serving as a pressing tool. The hub 32 is cylindrical. A hole spline portion 32C is provided on the inner periphery of the hub 32. The hub 32 has a through hole 32G, an insertion hole 32F for inserting a pressing tool, and a thin-walled portion 32H. The through hole 32G is provided radially outward of the hole spline portion 32C. The through hole 32G penetrates the hub 32 in the axial direction from one end face (one side face 32A) of the hub 32 to the other end face (other side face 32B). The insertion hole 32F is formed from the outer peripheral side face 32D of the hub 32 toward the through hole 32G (radially inward). The thin-walled portion 32H is formed between the inner diameter side of the insertion hole 32F and the hole spline portion 32C. That is, the thin portion 32H is formed between the through hole 32G of the hub 32 and the hole spline portion 32C.

[0050] The rotating shaft 34 corresponds to the rotating shaft of the hydraulic pump 15 mounted on the hydraulic excavator 1 (construction machine). The rotating shaft 34 has a shaft spline portion 34A provided on the outer periphery of the tip end (the right end in Figures 6, 8, and 9). The shaft spline portion 34A of the rotating shaft 34 is spline-coupled to the hole spline portion 32C of the hub 32. The clamping screw 35 is inserted into the insertion hole 32F of the hub 32. The clamping screw 35 is a male thread and is screwed into the female thread insertion hole 32F. The clamping screw 35 presses the thin-walled portion 32H. By pressing the thin-walled portion 32H, the clamping screw 35 constrains the hole spline teeth 32C1 of the hole spline portion 32C and the axial spline teeth 34A1 of the axial spline portion 34A.

[0051] 6 and 7, the axial spline teeth 34A1 and the bore spline teeth 32C1 have tapered surfaces 43, 52 inclined in a direction that the height increases toward the tip side in the axial direction at end portions 42, 53 on the base end side (left side in FIGS. 6 and 7) opposite to the tip side (right side in FIGS. 6 and 7) in the axial direction of the rotating shaft 34. That is, the axial spline teeth 34A1 have a tapered surface 43 inclined in a direction that the height increases toward the tip side (right side in FIGS. 6 and 7) at end portion 42 on the base end side (left side in FIGS. 6 and 7) in the axial direction of the rotating shaft 34. In other words, the axial spline portion 34A has a tapered surface 43 that is an axial spline tapered surface formed at end portion 42 on the base end side opposite to the tip side of the axial spline teeth 34A1 in the axial direction of the rotating shaft 34. The tapered surface 43 corresponds to the portion where the spline length increases in the axial direction from the tip to the root of the axial spline tooth 34A1 or further to the small diameter of the rotary shaft 34.

[0052] Furthermore, the hole spline tooth 32C1 has a tapered surface 52 at an end 53 on the base end side (left side in FIGS. 6 and 7) in the axial direction of the rotating shaft 34, which is inclined in a direction in which the height increases toward the tip end side (right side in FIGS. 6 and 7). In other words, the hole spline portion 32C has a tapered surface 52, which is a hole spline tapered surface, formed at an end 53 on the base end side in the axial direction of the hole spline tooth 32C1. The tapered surface 52 corresponds to the portion where the spline length increases in the axial direction from the tip of the hole spline tooth 32C1 to the root or further to the large diameter of the spline hole in the hub 32.

[0053] 7 and 14(B), in this embodiment, the tapered surface 43 of the axial spline tooth 34A1 and the tapered surface 52 of the hole spline tooth 32C1 intersect when viewed from the circumferential direction in a state in which the hole spline portion 32C and the axial spline portion 34A are splined together. That is, the tapered surface 43 of the axial spline tooth 34A1 is formed so as to intersect with the tapered surface 52 of the hole spline tooth 32C1 when viewed from the circumferential direction of the hub 32 in a state in which the hole spline portion 32C and the axial spline portion 34A are splined together. Furthermore, the tapered surface 52 of the hole spline tooth 32C1 is formed so as to intersect with the tapered surface 43 of the axial spline tooth 34A1 when viewed from the circumferential direction of the hub 32 in a state in which the hole spline portion 32C and the axial spline portion 34A are splined together. Therefore, when the tapered surfaces 43 of the axial spline teeth 34A1 and the tapered surfaces 52 of the bore spline teeth 32C1 are viewed in the circumferential direction of the rotating shaft 34, the ridge line of the tapered surface 43 located on the front side intersects with the ridge line of the tapered surface 52 located on the rear side, as shown in Fig. 7. In this case, the tapered surfaces 43 of all of the axial spline teeth 34A1 that constitute the axial spline portion 34A and the tapered surfaces 52 of all of the bore spline teeth 32C1 that constitute the bore spline portion 32C all intersect with the tapered surfaces of other members that are adjacent to them in the circumferential direction, as shown in Fig. 7.

[0054] 7 and 14(B), the intersecting position X is preferably closer to the center of the spline tooth height of the tapered surface 43 of the axial spline tooth 34A1. That is, the intersecting position X is preferably half the height H (FIG. 7) of the tapered surface 43 of the axial spline tooth 34A1, or a position (lower position) closer to the inner diameter side of the rotating shaft 34.

[0055] Furthermore, the bore spline tooth 32C1 has a tooth root extension portion 54 that extends axially at a height lower than the height of the axial intermediate portion 51 of the bore spline tooth 32C1, axially closer to the base end than the tapered surface 52. The tooth root extension portion 54 has a shape that leaves a tooth height that is greater than the radius of the tooth root from the tooth bottom diameter of the bore spline. An end portion of the tooth root extension portion 54 on the base end side in the axial direction abuts against an abutment surface 44 of the rotating shaft 34 that determines the axial position of the hub 32. Furthermore, the rotating shaft 34 on which the axial spline portion 34A is provided has a relief groove 41 axially closer to the base end than the tapered surface 43 of the axial spline tooth 34A1.

[0056] That is, a clearance groove 41 is formed in the circumferential direction on the outer peripheral surface of the rotating shaft 34. The clearance groove 41 is formed continuous with the tapered surface 43 of the axial spline tooth 34A1. The clearance groove 41 is formed on the rotating shaft 34 as a full-circumferential groove having a depth dimension greater than the height dimension of the axial spline tooth 34A1 (the depth dimension of the valley between the axial spline teeth 34A1 adjacent in the circumferential direction). The clearance groove 41 faces the root extension portion 54 of the bore spline tooth 32C1 in the radial direction when the bore spline portion 32C and the axial spline portion 34A are spline-coupled.

[0057] The hydraulic excavator 1 and spline connecting device 31 according to the embodiment have the configurations described above, and their operation will now be described.

[0058] The operator of the hydraulic excavator 1 sits in the cab 6 of the upper rotating body 3 and starts the engine 9 to drive the hydraulic pump 15. This causes the hydraulic pump 15 to discharge pressurized oil, which is then supplied via a control valve (not shown) to hydraulic actuators such as the boom cylinder 4D, arm cylinder 4E, bucket cylinder 4F, traveling hydraulic motor, and swing hydraulic motor.

[0059] When an operator in the cab 6 operates a travel control lever (not shown), the vehicle can be moved forward or backward by the undercarriage 2. On the other hand, an operator in the cab 6 operates a work control lever to rotate the work implement 4, thereby performing work such as excavating earth and sand. When the hydraulic excavator 1 is in operation, torque output from the output shaft 11 of the engine 9 is transmitted to the rotating shaft 34 of the hydraulic pump 15 via the shaft coupling 17. At this time, the torque output from the output shaft 11 of the engine 9 is transmitted to the rotating shaft 34 of the hydraulic pump 15 via the spline coupling device 31, i.e., the hole spline portion 32C of the hub 32 and the shaft spline portion 34A of the rotating shaft 34.

[0060] According to this embodiment, the axial spline teeth 34A1 and the bore spline teeth 32C1 have tapered surfaces 43, 52 that are inclined in a direction that increases in height toward the tip end at end portions 42, 53 on the base end side, which is opposite the tip end side in the axial direction of the rotating shaft 34. Furthermore, the ridge line of the tapered surface 43 of the axial spline teeth 34A1 and the ridge line of the tapered surface 52 of the bore spline teeth 32C1 appear to intersect when viewed from the circumferential direction of the hub 32 in a state in which the bore spline portion 32C and the axial spline portion 34A are spline-coupled. That is, the tapered surfaces 43 and 52 are formed to intersect when viewed from the circumferential direction of the hub 32 in a state in which the bore spline portion 32C and the axial spline portion 34A are spline-coupled. Therefore, the axial base end sides of the axial spline teeth 34A1 and the axial base end sides of the hole spline teeth 32C1 are in circumferential contact with each other at the ends 42, 53 having tapered surfaces 43, 52, i.e., the ends 42, 53 having the same rigidity.

[0061] This allows the amounts of bending deformation of the end portions 42, 53 (the end portions 42, 53 having the tapered surfaces 43, 52) of the hole spline teeth 32C1 and the axial spline teeth 34A1 on the base end side in the axial direction to be equalized when a rotational force is transmitted between the hole spline portion 32C and the axial spline portion 34A based on the spline connection therebetween, thereby equalizing stress. As a result, stress (stress concentration) of the end portions 42, 53 on the base end side in the axial direction of the hole spline teeth 32C1 and the axial spline teeth 34A1 can be alleviated. Furthermore, since the stress can be alleviated, not only can fatigue strength be improved, but the diameters of the hub 32 and the rotating shaft 34 can be set small, allowing the spline coupling device 31 to be made more compact.

[0062] According to the embodiment, the hole spline tooth 32C1 has a tooth root extension portion 54 that extends in the axial direction at a height lower than the height of the axial intermediate portion 51 of the hole spline tooth 32C1, on the base end side of the tapered surface 52. Therefore, the tooth root extension portion 54 can distribute stress on the end portion 53 on the base end side of the hole spline tooth 32C1, and this also can relieve stress, thereby improving fatigue strength.

[0063] According to the embodiment, the rotating shaft 34 has the relief grooves 41 on the base end side in the axial direction relative to the tapered surfaces 43 of the axial spline teeth 34A1. Therefore, when the axial spline portion 34A (axial spline teeth 34A1) is formed on the rotating shaft 34, the machining tool for forming the axial spline portion 34A (axial spline teeth 34A1) can escape into the relief grooves 41. Furthermore, even when the relief grooves 41 are formed, the tapered surfaces 43 of the axial spline teeth 34A1 and the tapered surfaces 52 of the hole spline teeth 32C1 intersect when viewed from the circumferential direction, thereby reducing stress on the end portions 42, 53 on the base end side in the axial direction of the hole spline teeth 32C1 and the axial spline teeth 34A1.

[0064] According to the embodiment, the relief groove 41 faces the root extension 54 of the hole spline tooth 32C1 in the radial direction when the hole spline portion 32C and the shaft spline portion 34A are spline-coupled. Therefore, the portion of the inner surface of the hub 32 that faces the relief groove 41 of the rotating shaft 34 in the radial direction can be the root extension 54 of the hole spline tooth 32C1. Furthermore, by providing the root extension 54 on the base end side of the tapered surface 52 of the hole spline tooth 32C1, the contact area with the abutment surface 44 of the rotating shaft 34 that positions the hub 32 in the axial direction can be increased compared to a configuration in which the root extension 54 is not provided (a modified example shown in FIG. 14(C) to be described later). This makes it possible to prevent the hub 32 from shifting axially relative to the rotating shaft 34 and the central axis of the hub 32 from tilting relative to the central axis of the rotating shaft 34.

[0065] According to the embodiment, the rotating shaft 34 is the rotating shaft 34 of the hydraulic pump 15 mounted on the hydraulic excavator 1. Therefore, the hydraulic pump 15 of the hydraulic excavator 1 and the engine 9 can be connected by the spline coupling device 31, and stress on the base end side in the axial direction of the hole spline teeth 32C1 and the shaft spline teeth 34A1 of the spline coupling device 31 can be alleviated.

[0066] In the embodiment, the case where the root extension portion 54 is provided on the base end side of the hole spline tooth 32C1 has been described as an example. However, the present invention is not limited to this. For example, as in a modified example shown in Fig. 14(C), the root extension portion may not be provided on the base end side of the hole spline tooth 32C1. In this case as well, the tapered surface 43 of the axial spline tooth 34A1 and the tapered surface 52 of the hole spline tooth 32C1 intersect as viewed from the circumferential direction when the hole spline portion 32C and the axial spline portion 34A are spline-coupled.

[0067] Therefore, in the modified example, similar to the embodiment, the end portions 42, 53 having the tapered surfaces 43, 52 at the base end sides of the axial spline teeth 34A1 and the base end sides of the axial spline teeth 32C1 in the axial direction abut against each other in the circumferential direction, i.e., the end portions 42, 53 having the same rigidity. As a result, in the modified example, similar to the embodiment, the amounts of deformation due to bending of the end portions 42, 53 (the end portions 42, 53 having the tapered surfaces 43, 52) at the base end sides in the axial direction of the bore spline teeth 32C1 and the axial spline teeth 34A1 can be made equal, and stress (stress concentration) at these end portions 42, 53 can be alleviated.

[0068] In the embodiment, the case where the tapered surfaces 43, 52 adjacent in the circumferential direction intersect with each other as viewed from the circumferential direction has been described as an example for all of the axial spline teeth 34A1 constituting the axial spline portion 34A and all of the bore spline teeth 32C1 constituting the bore spline portion 32C. However, this is not limited to this. For example, the tapered surfaces adjacent in the circumferential direction may intersect with each other as viewed from the circumferential direction for one or more of the bore spline teeth constituting the bore spline portion that are positioned corresponding to the pressing tool (clamping screw) and for one or more of the axial spline teeth adjacent to the bore spline teeth. That is, the tapered surfaces adjacent in the circumferential direction may intersect with each other for all spline teeth, or for some spline teeth, i.e., spline teeth that require stress (stress concentration) relief. Furthermore, the tooth root extensions may be provided for all of the bore spline teeth, or may be provided on the base end side of some of the bore spline teeth, i.e., for some of the bore spline teeth that require stress dispersion.

[0069] In the embodiment, the hydraulic excavator 1 is configured to use the engine 9 as a prime mover, and the spline coupling 31 has been described as an example of a device that transmits rotational force between the engine 9 and the hydraulic pump 15 (more specifically, between the shaft coupling 17 and the hydraulic pump 15). However, the present invention is not limited to this, and the spline coupling may be used, for example, as a motor such as an electric motor or a generator motor (assist generator motor) as a prime mover, and the spline coupling may transmit power between the motor and the hydraulic pump. Furthermore, the spline coupling device is not limited to a spline coupling device mounted on a construction machine, but can be widely used as a spline coupling device for various types of machinery and equipment that transmits rotational force between a hub and a rotating shaft.

[0070] The embodiments and modifications are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments and modifications is possible. [Explanation of symbols]

[0071] 1. Hydraulic excavator (construction machinery) 15 Hydraulic pump 31 Spline coupling device 32 Hub 32C hole spline part 32C1 hole spline teeth 32F insertion hole 32G through hole 32H Thin wall part 34 Rotation axis 34A Shaft spline part 34A1 shaft spline teeth 35 Clamping screw (pressure tool) 41 Relief groove (groove) 42,53 End 43 Tapered surface (axial spline tapered surface) 52 Tapered surface (hole spline tapered surface) 51 Middle section 54 Root extension

Claims

1. a cylindrical hub having a hole spline portion formed on its inner periphery; a rotary shaft having a tip end and a shaft spline portion on the outer periphery thereof that is splined to the hole spline portion, the hub has a through hole provided radially outward of the hole spline portion, the through hole penetrating the hub in an axial direction from one end surface to the other end surface; an insertion hole formed from an outer peripheral side surface of the hub toward the through hole; a thin-walled portion formed between the through hole of the hub and the hole spline portion, a pressing tool that is inserted into the insertion hole of the hub and presses the thin-walled portion, The axial spline portion has an axial spline tapered surface formed at an end portion on a base end side opposite to a tip end side of the axial spline teeth in the axial direction of the rotation shaft, The hole spline portion has a hole spline tapered surface formed at an end portion on the base end side in the axial direction of the hole spline teeth, the shaft spline tapered surface and the hole spline tapered surface are formed so as to intersect when viewed from the circumferential direction of the hub in a state in which the hole spline portion and the shaft spline portion are spline-coupled together, A spline connection device characterized by:

2. The hole spline tooth has a tooth root extension portion that is located on the base end side of the hole spline tapered surface and extends in the axial direction at a height lower than the height of an axial intermediate portion of the hole spline tooth.

2. The spline connector according to claim 1.

3. The rotating shaft has a groove on the base end side of the axial spline tapered surface of the axial spline teeth.

2. The spline connector according to claim 1.

4. a groove is formed in the outer peripheral surface of the rotating shaft along the circumferential direction, The grooves are formed continuously on the axial spline tapered surface of the axial spline teeth, The groove faces the root extension of the hole spline tooth in a radial direction.

3. The spline connector according to claim 2.

5. The rotating shaft is a rotating shaft of a hydraulic pump mounted on a construction machine.

2. The spline connector according to claim 1.

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