JP2021011901A - Differential gear - Google Patents

Abstract

To provide a differential gear including a cast differential case, and a differential gear mechanism stored in the differential case, the inner face of the differential case having a gear supporting face for the differential gear mechanism, for reducing the processing cost by eliminating the need for removing a parting line in post-processing work even when the parting line is left on the inner face of the differential case after cast.SOLUTION: In an inner face 3i of a differential case 3, recessed grooves G1-G3 passing through at least part of gear supporting faces 9s, 9p are molded with sand core N. The recessed grooves G1-G3 are arranged in positions where parting lines PL1-PL3 can be set into the recessed grooves G1-G3 even when the parting lines PL1-PL3 appear on the inner face 3i of the differential case 3 corresponding to die matching face fc of mutual core type half bodies C1, C2.SELECTED DRAWING: Figure 7

Description

The present invention relates to a differential device, particularly a cast differential case, and a differential gear mechanism housed in the differential case, the inner surface of the differential case having a gear support surface of the differential gear mechanism.

In the above differential device, molding the inner surface of the differential case with sand core is already known, for example, as disclosed in Patent Document 1 below.

JP-A-55-33842

By the way, the sand core for forming the inner surface of the differential case is formed by forming a pair of core halves each having a core forming surface, and both core halves are formed in the molding process. When matching the molds, the two core mold halves may be slightly displaced from each other along the mold matching surface.

Then, this deviation may cause, for example, a stepped parting line on the surface of the sand core (thus, the inner surface of the diff case after casting), but the parting line is particularly placed on the gear support surface on the inner surface of the diff case. If it is formed, it is necessary to remove it by post-processing, which causes a problem that the processing cost increases.

The present invention has been proposed in view of the above, and an object of the present invention is to provide a differential device capable of solving the above problems with a simple structure.

In order to achieve the above object, the present invention includes a cast differential case and a differential gear mechanism housed in the differential case, and the inner surface of the differential case is formed by matching a pair of core halves with each other. In a differential device having a gear support surface of the differential gear mechanism, a concave groove passing through at least a part of the gear support surface is formed on the inner surface of the differential case while being formed from the sand core formed by the above. It is formed of the sand core, and the concave groove is formed in the concave groove even if a parting line is generated on the inner surface of the differential case corresponding to the mating surfaces of the core mold halves. The first feature is that it is arranged at a position where the line can be accommodated.

Further, in addition to the first feature, the differential gear mechanism is rotatable around a pair of side gears that can rotate around the first axis and a second axis that is orthogonal to the first axis. It is provided with a pair of pinion gears that mesh with the pair of side gears, and the gear support surface has a pair of side gear support surfaces and a pair of pinion gear support surfaces that support the side gears and the back surfaces of the pinion gears. , The concave groove is a plane orthogonal to the first axis line, and the concave groove is a parting line existing on a first virtual plane orthogonal to the first axis line and dividing the pinion gear support surface in the pinion gear support surface. The second feature is that it is arranged at a position where it can accommodate.

Further, in the present invention, in addition to the first feature, the differential gear mechanism can rotate around a pair of side gears that can rotate around the first axis and around a second axis that is orthogonal to the first axis. It is provided with a pair of pinion gears that mesh with the pair of side gears, and the gear support surface has a pair of side gear support surfaces and a pinion gear support surface that support the side gears and the back surfaces of the pinion gears. A third aspect of the side gear support surface is that it is arranged at a position where the parting line existing on the second virtual plane that is between the pair of pinion gear support surfaces and divides the side gear support surface into two can be accommodated. It is a feature of.

Further, in the present invention, in addition to the first feature, the differential gear mechanism can rotate around a pair of side gears that can rotate around the first axis and around a second axis that is orthogonal to the first axis. It is provided with a pair of pinion gears that mesh with the pair of side gears, and the gear support surface has a pair of side gear support surfaces and a pinion gear support surface that support the side gears and the back surfaces of the pinion gears. A fourth feature is that the side gear support surface and the pinion gear support surface are arranged at positions where the parting line existing on the third virtual plane that divides the side gear support surface and the pinion gear support surface into two can be accommodated. And.

According to the first feature, in the differential case, a concave groove passing through at least a part of the gear support surface is formed of sand core together with the inner surface of the differential case, and the concave groove is a mold matching for forming the sand core. Even if a parting line is generated on the inner surface of the differential case corresponding to the surface, the parting line is arranged at a position where the parting line can be accommodated in the concave groove. As a result, even if a stepped parting line remains on the inner surface of the differential case after casting, for example, it stays in the concave groove and does not protrude into the gear support surface, so that the parting line is removed by post-processing. There is no need, and processing costs can be reduced. Moreover, since the concave groove can also be used as an oil groove for guiding the lubricating oil to the gear support surface, the structure can be simplified and further cost reduction can be contributed.

According to the second feature, the side gear support surface on the inner surface of the differential case is a plane orthogonal to the first axis, and the concave groove is located on the first virtual plane orthogonal to the first axis on the pinion gear support surface. Since it is in a position where the parting line can be accommodated, the direction along the first axis is the die-cutting direction of the sand core after molding. As a result, the side gear support surface, which is a plane orthogonal to the first axis, does not need to have a draft set, so that the side gear support surface can be accurately formed without post-processing or while reducing the amount of post-processing. It becomes. Moreover, since the concave groove exists on the pinion gear support surface, it can also be used as an oil groove for guiding lubricating oil to the pinion gear support surface.

According to the third feature, the concave groove is located on the side gear support surface on the inner surface of the differential case between the pair of pinion gear support surfaces and on the second virtual plane that bisects the side gear support surfaces. Since it is in a position to accommodate the line, there is no risk of the recessed groove (and therefore the parting line) crossing the pinion gear support surface. As a result, each pinion gear support surface can be accurately formed by a single mold (that is, one or the other core mold half body). Moreover, since the concave groove exists on the side gear support surface, it can also be used as an oil groove for guiding lubricating oil to the side gear support surface.

Further, according to the fourth feature, the concave groove is located on the side gear support surface and the pinion gear support surface at a position where the parting line existing on the third virtual plane that divides the gear support surfaces into two can be accommodated. , The concave groove (hence, the parting line) is arranged to cross not only the side gear support surface but also the pinion gear support surface, and can be used as an oil groove for guiding lubricating oil to both the side gear support surface and the pinion gear support surface.

Overall vertical sectional view (1-1 line sectional view of FIG. 2) showing the differential device according to the first embodiment. Section 2-2 sectional view of FIG. Perspective view of the differential case alone Side view of the differential case alone (4 arrow view in Fig. 3) It is a plan view of a single differential case (5 arrow view in FIG. 3), and shows an example in which the differential case and the processing device are positioned in the first axis direction by the first positioning jig. Front view of the differential case alone as seen from the first bearing boss side (6 arrow view in FIG. 3) Section 7-7 of FIG. 6 Section 8-8 of FIG. 9-9 is a cross-sectional view taken along the line 9-9 of FIG. 4, showing an example in which the differential case and the processing apparatus are positioned in the second and third axis directions by the second positioning jig. Perspective view showing an example of sand core used for casting a differential case In the 11th arrow view of FIG. 10, (a) shows the relationship between the sand core and the sand core molding die, and (b) shows the relationship between the sand core and the contour of the differential case (hence, the casting mold body). Show The second embodiment is shown, in which (a) is a perspective view of a single differential case, (b) is a view taken along the line b of FIG. 12 (a), and (c) is a line cc of FIG. 12 (b). Sectional view, (d) is a sectional view taken along line dd of FIG. 12 (b). A third embodiment is shown, in which (a) is a perspective view of a single differential case, (b) is a view taken along the line b of FIG. 13 (a), and (c) is a line cc of FIG. 13 (b). Sectional view, FIG. 13D is a sectional view taken along line dd of FIG. 13B. The fourth embodiment is shown, in which (a) is a perspective view of a single differential case, (b) is a view taken along the line b of FIG. 14 (a), and (c) is a line cc of FIG. 14 (b). Sectional view, (d) is a sectional view taken along line dd of FIG. 14 (b). The fifth embodiment is shown, in which (a) is a perspective view of a single differential case, (b) is a view taken along the line b of FIG. 15 (a), and (c) is a line cc of FIG. 15 (b). Sectional view, (d) is a sectional view taken along line dd of FIG. 15 (b). The sixth embodiment is shown, in which (a) is a perspective view of a single differential case, (b) is a view taken along the line b of FIG. 16 (a), and (c) is a line cc of FIG. 16 (b). Sectional view, FIG. 16D is a sectional view taken along line dd of FIG. 16B. The seventh embodiment is shown, in which (a) is a perspective view of a single differential case, (b) is a sectional view taken along line bb of FIG. 17 (a), and (c) is a perspective view of a sand core (FIG. 10 correspondence diagram) Eighth embodiment is shown, in which FIG. 8A is a perspective view of a single differential case, FIG. 18B is a sectional view taken along line bb of FIG. 18A (corresponding to FIG. 12B), (c). Is a perspective view of the sand core (corresponding to FIG. 17 (c))

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, the first embodiment will be described with reference to FIGS. 1 to 11. In FIG. 1, a differential in which power from a power source (for example, an in-vehicle engine) (not shown) is distributed and transmitted to left and right axles S1 and S2 as a pair of output shafts in a transmission case MC of a vehicle (for example, an automobile). The device 10 is housed. The differential device 10 includes a metal differential case 3 and a differential gear mechanism 20 built in the differential case 3.

The differential case 3 is a hollow case body 3c in which the differential gear mechanism 20 is housed, and first and second bearings that are integrally connected to the right side and left side of the case body 3c and lined up on the first axis X1. The bosses 3b1 and 3b2 and a flange portion 3f that is integrally formed on the outer peripheral portion of the case body 3c in the radial direction outward and extends in the circumferential direction of the circle centered on the first axis X1 are provided. The case body 3c is formed in a substantially spherical shape, and the inner surface 3ci thereof is formed in a spherical shape around the center O of the differential case 3.

Then, the first and second bearing bosses 3b1, 3b2 are rotatably supported by the mission case MC around the first axis X1 via the bearings 13 and 14 on the outer peripheral side of the bosses 3b1, 3b2. Further, bearing holes h1 and h2 extending in the direction of the first axis X1 pass through the central portion of the first and second bearing bosses 3b1 and 3b2, and the left and right axles S1 are formed in both bearing holes h1 and h2. , S2 are rotatably fitted and supported, respectively. The inner peripheral surfaces of the bearing holes h1 and h2 form a part of the inner surface 3i of the differential case 3.

Although not shown, a screw pump that sends lubricating oil in the transmission case MC into the differential case 3 on one of the fitting surfaces of the bearing bosses 3b1 and 3b2 and the axles S1 and S2 as the relative rotation with the other side occurs. If necessary, a spiral groove that can exert its action may be machined. Alternatively, an oil groove on a straight line along the first axis X1 may be formed on the inner peripheral surfaces of the bearing bosses 3b1 and 3b2 at the time of casting.

The flange portion 3f of the differential case 3 is integrally projected from the outer peripheral surface of the case body 3c in a ring plate shape, and the inner peripheral hub portion Rb of the ring gear R is detachably connected to the outer peripheral surface of the case body 3c by a plurality of bolts B. The flange portion 3f in the illustrated example is arranged at a position offset from the center O of the case body 3c toward the second bearing boss 3b2 in the axial direction (that is, the direction along the first axis X1).

The ring gear R has a helical gear (oblique tooth) -shaped tooth portion Rag on the outer periphery, and the tooth portion Rag meshes with a drive gear 31 which is an output unit of a transmission connected to a power source. Then, the rotational driving force from the driving gear 31 is transmitted to the case body 3c of the differential case 3 via the ring gear R and the flange portion 3f. In FIG. 1, the tooth portion Rag is displayed in cross section along the tooth muscle in order to simplify the display.

The differential gear mechanism 20 is rotatably connected to a pinion shaft 21 arranged on the second axis X2 orthogonal to the first axis X1 at the center O of the case body 3c and supported by the case body 3c, and the pinion shaft 21. A pair of supported pinion gears 22 and 22 and left and right side gears 23 and 23 that mesh with each pinion gear 22 and are rotatable around the first axis X1 are provided. The side gears 23 and 23 function as output gears of the differential gear mechanism 20, and the inner end portions of the left and right axles S1 and S2 are spline-fitted on the inner peripheral surfaces of the side gears 23 and 23. ..

The back surfaces of the pinion gear 22 and the side gear 23 are provided with pinion gear washers Wp and side gear washers Ws on the pinion gear support surface 9p and the side gear support surface 9s provided on the inner surface 3i of the differential case 3 (more specifically, the inner surface 3ci of the case body 3c), respectively. It is rotatably supported via (or directly without washers).

The pinion shaft 21 is inserted and held in a pair of pinion shaft support holes 3ch formed at the outer peripheral end of the case body 3c and extending on the second axis X2. Further, a retaining pin 17 penetrating across one end of the pinion shaft 21 is inserted (for example, press-fitted) into the case body 3c, and the retaining pin 17 separates the pinion shaft 21 from the pinion shaft support hole 3ch. Is blocked.

At least a part of the inner surface 3ci of the case body 3c (for example, the pinion shaft support hole 3ch) is machined by a processing device, for example, a machining tool (for example, a drill) of a machining center after casting the differential case 8 in the present embodiment.

Then, the rotational driving force transmitted from the drive gear 31 to the case body 3c of the differential case 3 via the ring gear R is distributed and transmitted to the left and right axles S1 and S2 via the differential gear mechanism 20 while allowing differential rotation. Will be done. Since the differential function of the differential gear mechanism 20 is well known in the past, the description thereof will be omitted.

As shown in FIGS. 2 to 4, the differential case 3 has a pair of work windows H on the side wall of the case body 3c on the side of the first bearing boss 3b1 with respect to the flange portion 3f in the direction along the first axis X1. The pair of work windows H are arranged on both sides of the second axis X2 when viewed on a projection plane orthogonal to the first axis X1 (see, for example, FIGS. 2 and 6), in other words, the first. 1, It is formed on the side wall of the case body 3c so as to be symmetrically arranged on both sides of the virtual plane F3 including the second axis X1 and X2.

The side wall portion 30 of the case body 3c sandwiched between the pair of work windows H is curved in a dome shape toward the first bearing boss 3b1 and is wide extending along the second axis X2 when viewed from the projection surface. It is formed in the shape of a band. In the strip-shaped side wall portion 30, the first bearing boss 3b1 is continuously provided in the intermediate portion, and both end portions (that is, the portion that becomes the outer peripheral end portion of the case body 3c) are integrally connected to the inner peripheral portion of the flange portion 3f. To.

The work window H is a work window for allowing cutting work on the inner surface 3ci of the case body 3c and assembling the differential gear mechanism 20 into the case body 3c, and is formed in a sufficiently large shape suitable for the purpose. To. That is, the work window H of the present embodiment is formed so as to extend along the first axis X1 to the root portion of the flange portion 3f and to open widely in the circumferential direction of the case body 3c.

By the way, the differential case 3 is cast and molded from a metal material (for example, aluminum, aluminum alloy, cast iron, etc.), and a predetermined portion of the differential case 3 is machined after the casting. The machined parts to be machined include, for example, pinion shaft support holes 3ch, bearing holes h1, h2, outer peripheral surfaces of the first and second bearing bosses 3b1, 3b2, side gear support surfaces 9s, and bolt holes of the flange part 3f. Etc. are included. It should be noted that FIGS. 3 to 9 show the differential case 3 in a single state, and these show each part of the differential case 3 after the machining is completed.

Further, as will be described later, the differential case 3 uses a single sand core N during casting to form an inner surface 3i of the differential case 3 (more specifically, an inner surface 3ci of the case body 3c and bearing holes h1 and h2). , The same-molded outer surface exposed to the outside of the case, which is the surface to be molded other than the inner surface 3i, is molded at the same time. The same-molded outer surface includes, for example, a work window H. Then, around the work window H (for example, the opening edge Ha of the work window H and its peripheral portion (for example, a specific flat portion f1 on the outer surface of the case body 3c facing the work window H, which is flush with the side surface of the flange portion 3f)). Is a part of the same-molded outer surface, and includes a surface that can be used as a processing reference surface during machining of the differential case 3 as described below.

The specific plane portion f1 described above is orthogonal to the first axis X1 and is used to position the differential case 3 and the processing device (not shown) in the direction of the first axis X1 when machining the differential case 3. It becomes the first processing reference plane of. For example, as illustrated in FIG. 5, by pressing a pair of tip portions J1a of the positioning jig J1 of the processing apparatus against the first processing reference surface f1, the differential case 3 and the processing apparatus are brought into the direction of the first axis X1. Positioning is possible. At the time of positioning, the processing apparatus is moved to the differential case 3 side with the differential case 3 fixed to some fixing means, but conversely, the differential case 3 is moved with the processing apparatus fixed. You may.

Further, a pair of second and third processing reference surfaces f2 are recessed in the opening edge portion Ha of each work window H at both ends in the direction of the second axis X2 in a notch shape. As illustrated in FIG. 9, the concave bottom surface of the second and third processing reference surfaces f2 is inclined toward the second axis X2 side from the first axis X1 toward the outer diameter side along the third axis X3. It is formed on each slope.

Then, as illustrated in FIG. 9, a pair of positioning jigs J2 and J2 of the processing apparatus are arranged so as to face each other with the virtual plane F3 including the first and second axis lines X1 and X2 in between, and both positioning jigs J2. The differential case 3 is sandwiched by both positioning jigs J2 in the direction of the third axis X3 so that the pair of tip portions J2a and J2a of the above are pressed against the second and third machining reference surfaces f2. As a result, the differential case 3 and the processing apparatus can be positioned at once in the directions of the second and third axes X2 and X3. Thus, the second and third processing reference planes f2 of the present embodiment are the above-mentioned first type processing reference planes.

As will be described later, the first processing reference surface f1 and the second and third processing reference surfaces f2 are formed together with the inner surface 3i of the differential case 3 by the same molding die, that is, the sand core N, when the differential case 3 is cast. To. Further, in the present embodiment, the first machining reference surface f1, the second and third machining reference planes f2, and the pinion gear support surface 9p are non-machined surfaces that are not machined even after casting the differential case 3.

By the way, FIGS. 10 and 11 show an example of the above-mentioned sand core N. That is, the sand core N forms a pair of bearing surfaces h1 and h2, which are connected to the substantially spherical inner surface forming portion Na of the main body and the inner surface forming portion Na of the main body, respectively, to form the inner surface 3ci of the case body 3c of the differential case 3. A pair of bearing surface forming portions Nb, a pair of window forming portions Nc connected to the main body inner surface forming portion Na to form a pair of working windows H of the differential case 3 and their peripheral portions, and a pair of window forming portions Nc. A pair of support arm portions Nd connected to each Nc are provided. Both supporting arm portions Nd are used to fix and support the sand core N in a casting mold (not shown) that has a cavity in which the sand core N is housed and installed and forms the outer surface of the differential case 3. Will be done.

Then, for molding the sand core N, for example, as simply shown in FIG. 11A, a core mold composed of first and second core mold halves C1 and C2 having a sand core molding surface. C is used. That is, the first and second core mold halves C1 and C2 are formed by inserting a sand material for casting between them and molding and solidifying them. Thus, on the outer surface of the sand core N, a minute protrusion or a minute step was formed corresponding to the mutual type matching surface fc of the first and second core type halves C1 and C2. Parting line PL1 may occur.

The mold matching surface fc is placed on a virtual plane passing through the center O of the case body 3c at least in the peripheral wall portion of the case body 3c so that the die cutting can be performed without any trouble even if the inner surface 3ci of the case body 3c is spherical. Set.

In particular, in the first and second core type halves C1 and C2 of the present embodiment, at the portion where the case body 3c is molded, the mutual mold matching surfaces fc pass through the center O of the case body 3c and the first axis line. The orientation is set in the so-called horizontal division direction orthogonal to X1 (hence, the orientation parallel to the first machining reference plane f1). As a result, even when the first and second core type halves C1 and C2 are slightly displaced in the direction along the mold matching surface fc and the molds are aligned, the first machining reference surface is in a parallel relationship with the mold matching surface fc. With f1, the differential case 3 and the processing apparatus can be positioned with each other in the direction of the first axis X1 without any trouble, so that the positioning accuracy can be improved.

Further, the first processing reference surface f1 is the first processing projecting from the sand core N, particularly the specific molding surface formed by the second core type half body C2 (more specifically, the outer surface of the molding portion Nc such as a window). It is molded by the reference surface forming portion Nca1).

On the other hand, the plurality of second and third processing reference surfaces f2 are specific forming surfaces (more specifically, window or the like forming portions) formed by sand core N, particularly the first core type half body C1. It is molded by each pair of second and third processing reference surface forming portions Nca2) projecting from the outer surface of Nc. The die-matching surface fc of the present embodiment is shown in the figure so that even if the second and third processing reference surface molding portions Nca2 are projected onto the outer surface of the molding portion Nc such as a window, the die-cutting is not hindered. As shown in 11 (a), the window or the like molding portion Nc is arranged so as to be in contact with the side surface of the second and third processing reference surface molding portions Nca2.

By the way, on the inner surface 3ci of the case body 3c, a concave groove G1 passing through a part of the pinion gear support surface 9p is formed by the sand core N at the same time as casting the differential case 3. The concave groove G1 is arranged on the pinion gear support surface 9p at a position where the parting line PL1 corresponding to the mold matching surface fc of the sand core N can be accommodated. Then, in the case body 3c, the parting line PL1 exists on a first virtual plane F1 that passes through the center O and is orthogonal to the first axis X1 and bisects the pinion gear support surface 9p.

Further, the concave groove G1 is formed by a concave groove forming ridge portion Naa projecting from the outer surface of the main body inner surface forming portion Na of the sand core N. In this case, the concave groove forming ridge portion Naa is formed so that the mold matching surface fc (hence, the parting line PL1) passes through the top portion thereof.

Further, in the portion corresponding to the main body inner surface forming portion Na of the sand core N, particularly the side gear support surface 9s, a plurality of oils are provided on the inner surface 3ci (more specifically, the side gear support surface 9s and its peripheral portion) of the case main body 3c. A plurality of oil passage forming protrusions Nao1 for forming the passage o1 are projected. Further, a plurality of projecting portions Nao2 for forming an engaging portion o2 that engages with a turning stop convex portion (not shown) projecting outward in the radial direction are also provided on the outer periphery of the side gear washer Ws. The oil passage o1 and the engaging portion o2 may be omitted if necessary.

Next, the operation of the first embodiment will be described.

The differential case 3 is cast and molded using the above-mentioned sand core N and a casting mold (not shown) that holds the sand core N at a predetermined position in the cavity, and after the casting, a predetermined portion of the differential case 3 is formed. It is machined. As the machined portion to be machined, for example, as described above, the pinion shaft support hole 3ch, the bearing holes h1 and h2, the outer peripheral surfaces of the first and second bearing bosses 3b1 and 3b2, the side gear support surface 9s and the like are included. included.

Then, in those machining, by pressing the positioning jig J1 of the machining apparatus (not shown) against the first machining reference surface f1 in advance, the differential case 3 and the machining apparatus are positioned in the first axis X1 direction, and further. By pressing the tip portions J2a and J2a of the pair of positioning jigs J2 of the processing apparatus against the plurality of second and third processing reference surfaces f2, the second and third axis lines X2 and X3 between the differential case 3 and the processing apparatus Directional positioning is done. Thus, the positioning in the three directions, that is, the directions of the first to third axes X1 to X3 is completed, and then the machining by the processing apparatus is started.

By the way, in the present embodiment, the inner surface 3i of the differential case 3 and the outer surface of the same mold exposed to the outside of the differential case 3 are simultaneously molded by a single sand core N (that is, the same molding mold) when casting the differential case 3. A work window H is included in the same-molded outer surface. Around the work window H, there are machining reference planes f1 and f2 that are a part of the same mold molding outer surface and serve as a reference plane for machining after casting. As a result, it is possible to eliminate or minimize the deviation of the relative position between the machined portion machined by the machining apparatus positioned based on the machining reference surfaces f1 and f2 and the inner surface 3i of the differential case 3. Therefore, when the portion communicating with the inner surface 3i or the inner surface 3i (for example, pinion shaft support hole 3ch, side gear support surface 9s, bearing hole h1, h2, etc.) is machined after casting the differential case 3, the amount of processing thereof It is possible to reduce the variation in bearings and the amount of processing.

Further, in the present embodiment, at least a part of the inner surface 3i of the differential case 3 (for example, the pinion gear support surface 9p) is a non-processed surface, but even in such a case, the non-processed surface (for example, the pinion gear support surface 9p) and the processed portion are used. Since the accuracy of the position relative to (for example, the pinion shaft support hole 3ch) can be improved, it is advantageous for smooth operation of the differential device 10.

Further, in particular, in the present embodiment, a part of the same mold outer surface is formed around a work window H formed by a single sand core N (that is, the same mold) when casting the differential case 3. , A plurality of machining reference surfaces f1 and f2 for positioning in three directions (directions of the first to third axes X1 to X3) are arranged with respect to the machining apparatus. As a result, the inner surface 3i of the differential case 3 and the inner surface 3i of the differential case 3 are formed by a single sand core N forming a region straddling the inner surface 3i of the differential case 3 and the periphery of the work window H (for example, the opening edge Ha and its peripheral portion). A plurality of processing reference surfaces f1 and f2 can be formed accurately and easily.

In addition, the pinion gear support surface 9p of the gear support surface on the inner surface 3i of the differential case 3 is a non-machined surface that is not machined even after casting of the differential case 3, so that the processing man-hours of the differential case 3 are reduced and the cost is reduced. Achieved.

Further, in the present embodiment, all of the plurality of second and third machining reference planes f2 for positioning the differential case 3 and the machining apparatus in the directions of the second and third axes X2 and X3 are sand cores N, particularly the third. 1 It is molded by a specific molding surface formed by the core type half body C1 (more specifically, a plurality of second and third processing reference surface forming portions Nca2 projecting from the outer surface of the forming portion Nc such as a window). As a result, even when the first and second core halves C1 and C2 are slightly displaced in the direction along the molding surface fc and the molds are aligned, the positions of the plurality of second and third processing reference surfaces f2 are mutually present. Since the relationship is accurately determined by the specific molding surface (second and third processing reference surface forming portion Nca2) derived from a single mold (that is, the first core mold half body C1), the differential case 3 and the processing apparatus are mutually determined. Can be positioned in the directions of the second and third axes X2 and X3 without any trouble, and the positioning accuracy is further improved.

By the way, in the differential case 3 of the present embodiment, the concave groove G1 passing through a part of the pinion gear support surface 9p is the concave groove of the sand core N (more specifically, the inner surface forming portion Na of the main body) together with the inner surface 3i of the differential case 3. The concave groove G1 is formed by the forming ridge portion Naa), and the concave groove G1 is formed even when the parting line PL1 is generated on the inner surface 3i of the differential case 3 corresponding to the mold matching surface fc of the sand core forming mold C. It is arranged at a position where the parting line PL1 can be accommodated inside.

As a result, even if the parting line PL1 is generated on the inner surface 3i of the differential case 3 after casting, it stays in the concave groove G1 and does not protrude into the pinion gear support surface 9p, so that the parting line PL1 is post-processed. It is not necessary to remove the above, and the processing cost can be reduced. Moreover, since the concave groove G1 is present on the pinion gear support surface 9p, it can also be used as an oil groove for guiding the lubricating oil to the pinion gear support surface 9p, so that the structure can be simplified and further cost reduction can be achieved. ..

Further, in the present embodiment, the side gear support surface 9s is a flat surface orthogonal to the first axis X1, and the concave groove G1 is on the first virtual plane F1 orthogonal to the first axis X1 on the pinion gear support surface 9p. Since it is arranged at a position where the parting line PL1 existing in the above can be accommodated, the direction along the first axis X1 is the die-cutting direction of the sand core N after mold forming. As a result, the side gear support surface 9s, which is a plane orthogonal to the first axis X1, does not need to have a special draft setting, so that the side gear support surface 9s can be reduced in the amount of post-processing without post-processing. However, it can be molded with high accuracy.

Further, FIG. 12 shows a second embodiment of the present invention. In the differential case 3 of the first embodiment, the second and third machining reference surfaces f2 provided around each work window H commonly position the second axis X2 and the third axis X3 in each direction on the same surface. Although the first type of machining reference plane is shown, in the second embodiment, the second and third machining reference planes f3 and f4 position the second axis X2 and the third axis X3 in each direction. It differs in that it is a second type machining reference plane that is individually performed on different planes.

That is, in the second embodiment, the outer surface of the case body 3c facing the work window H has a V-shaped cross section in the middle portion of the specific flat surface portion (that is, the first processing reference surface) f1 that is flush with the side surface of the flange portion 3f. The groove 42 is recessed, and the inner surface of the V-shaped groove 42 constitutes a machining reference surface f3 for positioning in the direction of the second axis X2, and is outside the intermediate portion of the opening edge Ha of the work window H. The side surface is formed on a plane orthogonal to the third axis X3, and constitutes a machining reference surface f4 for positioning in the direction of the third axis X3. Both of the processing reference surfaces f3 and f4 form the second and third processing reference surfaces of the present invention.

It should be noted that the two machining reference surfaces f3 and f4 are positioned by engaging with different positioning jigs (not shown) of the machining apparatus so as to be in contact with each other.

Since the other configurations of the second embodiment are the same as those of the first embodiment, each component of the second embodiment is provided with a reference code of the corresponding component of the first embodiment. The above description will be omitted. Further, also in this second embodiment, it is possible to achieve basically the same action and effect as in the first embodiment.

Further, FIG. 13 shows a third embodiment of the present invention. In this third embodiment, only the structure of the machining reference surface f5 for positioning the differential case 3 and the machining apparatus with each other, particularly the positioning in the direction of the second axis X2, is different from the second embodiment.

That is, in the third embodiment, the outer surface of the intermediate portion of the opening edge Ha of the work window H is formed in a plane orthogonal to the third axis X3, and the machining reference surface f4 for positioning in the direction of the third axis X3. The points constituting the above are the same as those of the processing reference surface f4 of the second embodiment, but in order to perform positioning in the direction of the second axis X2, particularly in the third embodiment, the inner peripheral surface of the window hole of the work window H , Both inner end faces in the direction of the second axis X2 constitute a machining reference surface f5 for positioning in the direction of the second axis X2.

It should be noted that the two machining reference surfaces f4 and f5 are positioned by engaging with different positioning jigs (not shown) of the machining apparatus so as to be in contact with each other.

Since the other configurations of the third embodiment are the same as those of the second embodiment, each component of the second embodiment is provided with a reference code for the corresponding component of the second embodiment. The above description will be omitted. Further, also in this third embodiment, it is possible to achieve basically the same effects as those in the second embodiment.

Further, in the third embodiment, all of the plurality of second and third machining reference surfaces f5 and f4 for positioning the differential case 3 and the machining apparatus in the directions of the second and third axes X2 and X3 are sand cores N. In particular, since it is molded by the specific molding surface formed by the first core type half body C1, the first and second core type half bodies C1 and C2 are slightly displaced in the direction along the mold matching surface fc. Even if this is done, the positional relationship between the plurality of second and third processing reference surfaces f5 and f4 is accurately determined by the specific forming surface derived from a single mold (that is, the first core mold half body C1). .. As a result, the differential case 3 and the processing apparatus can be positioned with each other in the directions of the second and third axes X2 and X3 without any trouble.

Further, FIG. 14 shows a fourth embodiment of the present invention. The fourth embodiment is similar to the first embodiment in that the second and third machining reference planes f6 provided around each work window H are the first type machining reference planes, but the first embodiment thereof. The structure of the second and third machining reference planes f6 is different from that of the second and third machining reference planes f2 of the first embodiment.

That is, regarding the positioning between the differential case 3 and the processing device, in the fourth embodiment, the specific flat surface portion (that is, the first processing reference surface) f1 of the outer surface of the case body 3c facing the work window H is flush with the side surface of the flange portion 3f. A pyramid-shaped recess 44 having a tapered bottom is provided in the middle portion of the above, and the inner surface of the pyramid-shaped recess 44 positions the second axis X2 and the third axis X3 in each direction. The surface f6 is formed.

Then, with respect to the first machining reference surface f1 and the second and third machining reference surfaces f6, the positioning convex portion J1aa that can be fitted into the second and third machining reference surfaces f6 as illustrated in FIG. 15 (d). By pressing the tip portion J1a of the positioning jig J1'on the tip surface, positioning of the first to third axes X1 to X3 in each direction is performed at once.

Since the other configurations of the fourth embodiment are the same as those of the first embodiment, each component of the fourth embodiment is provided with a reference code for the corresponding component of the first embodiment. The above description will be omitted. Further, also in this fourth embodiment, it is possible to achieve basically the same action and effect as in the first embodiment.

Further, in the fourth embodiment, the first machining reference surface f1 that positions the differential case 3 and the machining apparatus in the direction of the first axis X1, and a plurality of second processes that position the differential case 3 and the machining apparatus in the directions of the second and third axes X2 and X3. Since all of the third processing reference surfaces f6 are formed by the specific molding surface formed by the sand core N, particularly the second core type half body C2, the first and second core type half bodies C1 and C2 Even when the molds are aligned with each other slightly offset in the direction along the mold alignment surface fc, the positional relationship between the first processing reference surface f1 and the second and third processing reference surfaces f6 is a single mold (that is, the first type). Since it is accurately determined by the specific molding surface derived from the 2 core type half body C2), the differential case 3 and the processing apparatus can be positioned with each other in the directions of the first to third axes X1 to X3 without any trouble.

Further, FIG. 15 shows a fifth embodiment of the present invention. In the fifth embodiment, only the structure of the second and third machining reference surfaces f7 provided around each work window H and positioning the second axis X2 and the third axis X3 in each direction is the fourth embodiment. It is different from that of.

That is, in the fourth embodiment, the pyramid-shaped recess 44 is recessed in the intermediate portion of the outer surface of the case body 3c facing the work window H, which is a specific flat surface portion (that is, the first processing reference surface) f1 that is flush with the side surface of the flange portion 3f. The inner surface of the pyramid-shaped recess 44 is set as the second and third processing reference planes f6, but in the fifth embodiment, a cone is formed in the middle portion of the specific plane portion (that is, the first processing reference plane) f1. The shaped recess 45 is recessed, and the inner surface of the conical recess 45 constitutes the second and third processing reference surfaces f7.

Since the other configurations of the fifth embodiment are the same as those of the fourth embodiment, each component of the fifth embodiment is provided with a reference code for the corresponding component of the fourth embodiment. The above description will be omitted. Further, also in this fifth embodiment, it is possible to achieve basically the same effects as those in the fourth embodiment.

Further, FIG. 16 shows a sixth embodiment of the present invention. The sixth embodiment is similar to the first embodiment in that the second and third machining reference planes f8 provided around each work window H are the first type machining reference planes, but the first embodiment thereof. The structure of the second and third machining reference planes f8 is different from that of the second and third machining reference planes f2 of the first embodiment.

That is, with respect to the positioning between the differential case 3 and the processing apparatus, in the sixth embodiment, a groove 46 having a V-shaped cross section is recessed on the outer surface of the intermediate portion of the opening edge Ha of the work window H, and the V-shaped groove 46 is formed. The inner surface of the groove 46 constitutes the second and third machining reference surfaces f8 that position the second axis X2 and the third axis X3 in each direction.

Then, with respect to the second and third machining reference surfaces f8, the tip portions of a pair of positioning jigs (not shown) having a positioning convex portion that can be fitted into the second and third machining reference surfaces f8 are placed on the outside of both work windows H. By pressing from the side, positioning of the second axis X2 and the third axis X3 in each direction is performed at once.

Since the other configurations of the sixth embodiment are the same as those of the first embodiment, each component of the sixth embodiment is provided with a reference code for the corresponding component of the first embodiment. The above description will be omitted. Further, also in this sixth embodiment, basically the same action and effect as in the first embodiment can be achieved.

Further, FIG. 17 shows a seventh embodiment of the present invention. In the seventh embodiment, the molding surface of the sand core molding mold for forming the sand core for casting and molding the inner surface 3i of the differential case 3 and the parting line appearing on the inner surface 3i of the differential case 3 in connection therewith. The position of is different from that of the first to sixth embodiments.

That is, the first and second core type halves C1 and C2 used in the first to sixth embodiments are set in the so-called horizontal division direction in which the mutual type matching surface fc is orthogonal to the first axis X1. On the other hand, the type matching surface fc'of the first and second core halves C1 and C2 (not shown) used in the seventh embodiment includes the first axis X1 and is orthogonal to the second axis X2. Is set on the virtual plane F2 (that is, in the first vertical division direction).

Then, on the inner surface 3ci of the case body 3c, a parting line PL2 existing on the second virtual plane F2 corresponding to the mold matching surface fc'is generated, but the parting line PL2 is recessed at a position included in the groove inner surface. A groove G2 is formed. The concave groove G2 is formed by the sand core N'at the same time as the casting of the differential case 3.

More specifically, the concave groove G2 is formed by the concave groove forming ridge portion Naa'protruding on the outer surface of the main body inner surface forming portion Na'of the sand core N'. In this case, the concave groove forming ridge portion Naa'is formed so that the mold matching surface fc'(therefore, the parting line PL2) passes through the top of the ridge portion Naa'.

Thus, the recessed groove G2 of the seventh embodiment is located between the pair of pinion gear support surfaces 9p and on the second virtual plane F2 that bisects the side gear support surfaces 9s, particularly on the side gear support surface 9s. Since it is in a position where the existing parting line PL2 can be accommodated, there is no possibility that the concave groove G2 (hence, the parting line PL2) passes through the pinion gear support surface 9p. As a result, each pinion gear support surface 9p can be accurately formed by a single mold (that is, the pinion gear support surface forming portion of the sand core N'formed by the first or second core type halves C1 and C2). It can be molded. Moreover, since the concave groove G2 exists on the side gear support surface 9s, it can also be used as an oil groove for guiding the lubricating oil to the side gear support surface 9s.

Further, bearing holes h1 and h2 for inserting the axles S1 and S2 are opened in the side gear support surface 9s, and the concave groove G2 is directly communicated with the openings, so that the axles S1 and S2 and the bearing Lubricating oil flowing through the fitting portions of the holes h1 and h2 can be efficiently introduced to the side gear support surface 9s side. As a result, the lubrication performance of the side gear 23 and, by extension, the differential gear mechanism 20 in the differential case 3 can be improved.

Since the other configurations of the seventh embodiment are the same as those of the first embodiment, each component of the seventh embodiment is provided with a reference code for the corresponding component of the first embodiment. The above description will be omitted. Further, also in this seventh embodiment, it is possible to achieve basically the same action and effect as in the first embodiment.

Further, FIG. 18 shows an eighth embodiment of the present invention. The type matching surface fc'of the first and second core half bodies C1 and C2 used in the seventh embodiment is on the second virtual plane F2 including the first axis X1 and orthogonal to the second axis X2. (That is, in the first vertical division direction), in the eighth embodiment, the mold matching surface fc "is on the third virtual plane F3 including the first and second axis X1 and X2 (that is, in the first vertical division direction). That is, it differs from the seventh embodiment in that it is set in the second vertical division direction).

Then, on the inner surface 3ci of the case body 3c, a parting line PL3 existing on the third virtual plane F3 corresponding to the mold matching surface fc "is generated, and the parting line PL3 is recessed at a position included in the groove inner surface. A groove G3 is formed. The concave groove G3 is formed by the sand core N "at the same time as the casting of the differential case 3.

More specifically, the concave groove G3 is formed by the concave groove forming ridge portion Naa ″ projecting from the outer surface of the main body inner surface forming portion Na ″ of the sand core N ″. In this case, the concave groove forming is performed. The ridge Naa ″ is formed so that the molding surface fc ″ (hence the parting line PL3) passes through the top of the ridge portion Naa ″.

Thus, the recessed groove G3 of the eighth embodiment is a parting line existing on a third virtual plane F3 that bisects both gear support surfaces 9s and 9p, particularly on the side gear support surface 9s and the pinion gear support surface 9p. Since it is in a position where the PL3 can be accommodated, the concave groove G3 (hence, the parting line PL3) is arranged to cross not only the side gear support surface 9s but also the pinion gear support surface 9p, and the side gear support surface 9s and the pinion gear support surface 9p are arranged. It can also be used as an oil groove that guides lubricating oil to both.

Further, as in the seventh embodiment, the side gear support surface 9s has bearing holes h1 and h2 opened, and the concave groove G3 directly communicates with the openings, so that the axles S1 and S2 and the bearing holes are directly communicated with each other. Lubricating oil that flows through the mating parts of h1 and h2 can be efficiently introduced to the side gear support surface 9s side, and the lubrication performance of the side gear 23 and the differential gear mechanism 20 in the differential case 3 is improved. Be done.

Since the other configurations of the eighth embodiment are the same as those of the seventh embodiment, each component of the eighth embodiment is provided with a reference code for the corresponding component of the seventh embodiment. The above description will be omitted. And, in this 8th embodiment, basically the same action and effect as in the 7th embodiment can be achieved.

The structure of the characteristic portions (that is, the parting lines PL2, PL3 and the recessed grooves G2, G3) of the seventh and eighth embodiments described above may be applied to the first to sixth embodiments.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various design changes can be made without departing from the gist thereof.

For example, in the above embodiment, the differential device 10 is implemented as a vehicle differential device, particularly as a differential device between the left and right drive wheels. However, in the present invention, the differential device 10 is used as the front and rear drive wheels. It may be implemented as a differential between vehicles, or it may be implemented as a differential in various mechanical devices other than vehicles.

Further, in the above-described embodiment, the connection between the flange portion 3f of the differential case 3 and the ring gear R is coupled by a plurality of bolts B, but the coupling between the flange portion 3f and the ring gear R is welded (for example, laser welding, electron). It may be performed by beam welding or the like).

Further, in the above embodiment, the tooth portion Rag of the ring gear R is used as a helical gear, but the ring gear is another gear having a tooth shape that receives a thrust load in the direction along the first axis X1 by meshing with the drive gear 31. (For example, bevel gear, hypoid gear, etc.) may be used. Alternatively, a tooth-shaped gear (for example, a spur gear) that does not receive the thrust load due to meshing with the drive gear 31 may be used.

Further, in the above embodiment, the side gear support surface 9s is formed in a plane shape orthogonal to the first axis X1, but the side gear support surface 9s may be formed in a tapered surface or a spherical shape. Further, in the above embodiment, the pinion gear support surface 9p is formed in a spherical shape, but the pinion gear support surface 9p may be formed in a tapered surface or a plane shape orthogonal to the second axis X2.

Further, the machining reference surfaces f1 to f8 for machining the differential case 3 are formed by exposing them to the outer surface of the differential case 3 together with the inner surface 3i of the differential case 3 with sand cores N, N', N ″ as the same molding mold. The surface is not limited to the one shown in the above embodiment as long as it is included in the same molded outer surface and can position the differential case 3 and the processing apparatus in three directions orthogonal to each other.

Further, in the above-described embodiment, the work window H is included in the same-molded outer surface of the differential case 3 formed by the sand cores N, N', N ″, and a specific portion around the work window H is formed as a processing reference surface. Although those used for f1 to f8 are shown, a molded portion other than the work window H (for example, an opening for lubricating oil flow not shown in the differential case) included in the same mold outer surface is used as a machining reference surface. You may.

Further, in the above embodiment, the machining reference surfaces f1 to f8 for machining the diff case 3 after casting are all molded together with the diff case inner surface 3i by the same molding die (sand core N, N', N ″). However, in the present invention, at least a part of the processing reference surface may be formed by a molding die different from the sand core (for example, a casting die for forming the outer surface of the differential case).

C1, C2 ... 1st and 2nd core half bodies as a pair of core half bodies F1 to F3 ... 1st to 3rd virtual planes fc, fc', fc "... ~ G3 ... Recessed grooves h1, h2 ... Bearing holes N, N', N "... Sand core PL1 to PL3 ... First to third parting lines S1, S2 as parting lines ... Output shaft Left and right axles X1, X2 ... 1st and 2nd axis 3 ... Diff case 3i ... Diff case inner surface 9s, 9p ... Side gear support surface as gear support surface, pinion gear support surface 20 ... Differential gear mechanism 22 ... Pinion gear 23 ... Side gear

Claims (4)

A cast differential case (3) and a differential gear mechanism (20) housed in the differential case (3) are provided, and the inner surface (3i) of the differential case (3) is a pair of core half bodies (3i). C1, C2) It is formed of sand cores (N, N', N ″) formed by matching the molds with each other, and has a gear support surface (9s, 9p) of the differential gear mechanism (20). In a differential device
On the inner surface (3i) of the differential case (3), recessed grooves (G1 to G3) passing through at least a part of the gear support surface (9s, 9p) are formed by the sand cores (N, N', N ″). It is molded and
The recessed grooves (G1 to G3) correspond to the mating surfaces (fc, fc', fc ″) of the core half bodies (C1, C2) on the inner surface (3i) of the differential case (3). A differential device characterized in that even if a parting line (PL1 to PL3) is generated, it is arranged at a position where the parting line (PL1 to PL3) can be accommodated in the concave groove (G1 to G3). The differential gear mechanism (20) can rotate around a pair of side gears (23) that can rotate around the first axis (X1) and around a second axis (X2) that is orthogonal to the first axis (X1). A side gear support surface (22) is provided with a pair of pinion gears (22) that mesh with the pair of side gears (23), and the gear support surface supports the back surfaces of the side gear (23) and the pinion gear (22). It has a pair of 9s) and a pinion gear support surface (9p).
The side gear support surface (9s) is a plane orthogonal to the first axis (X1).
The recessed groove (G1) exists on a first virtual plane (F1) that is orthogonal to the first axis (X1) and divides the pinion gear support surface (9p) in the pinion gear support surface (9p). The differential device according to claim 1, wherein the differential device is arranged at a position where the parting line (PL1) can be accommodated. The differential gear mechanism (20) can rotate around a pair of side gears (23) that can rotate around the first axis (X1) and around a second axis (X2) that is orthogonal to the first axis (X1). A side gear support surface (22) is provided with a pair of pinion gears (22) that mesh with the pair of side gears (23), and the gear support surface supports the back surfaces of the side gear (23) and the pinion gear (22). It has a pair of 9s) and a pinion gear support surface (9p).
The concave groove (G2) is located between the pair of pinion gear support surfaces (9p) on the side gear support surface (9s) and divides the side gear support surface (9s) into two halves (F2). The differential device according to claim 1, wherein the differential device is arranged at a position where the parting line (PL2) existing above can be accommodated. The differential gear mechanism (20) can rotate around a pair of side gears (23) that can rotate around the first axis (X1) and around a second axis (X2) that is orthogonal to the first axis (X1). A side gear support surface (22) is provided with a pair of pinion gears (22) that mesh with the pair of side gears (23), and the gear support surface supports the back surfaces of the side gear (23) and the pinion gear (22). It has a pair of 9s) and a pinion gear support surface (9p).
The concave groove (G3) is a third virtual plane (9s) that divides the side gear support surface (9s) and the pinion gear support surface (9p) into two at the side gear support surface (9s) and the pinion gear support surface (9p). F3) The differential device according to claim 1, wherein the differential device is arranged at a position where the parting line (PL3) existing on the F3) can be accommodated.