JP7755366B2 - Work assembly device - Google Patents

Description

The present invention relates to a workpiece assembly device.

A well-known valve train mechanism installed in an internal combustion engine, such as an automobile engine, includes a cam connected to a camshaft, a rocker arm pressed by the cam, and a lash adjuster supporting one end of the rocker arm. In this valve train, the lash adjuster is assembled to a recess provided in the cylinder block.

Patent Document 1 listed below discloses a workpiece assembly device used when assembling a workpiece such as a lash adjuster to an assembly target. This workpiece assembly device includes a holding unit that holds the workpiece, and a pusher that moves coaxially with the holding unit relative to the holding unit to push the workpiece held by the holding unit outward and assemble it to the assembly target. As described in paragraphs 0022-0023 and Figure 2 of the document, the holding unit is composed of a cylinder into whose inner periphery the workpiece is inserted, holding pins that are spaced apart at multiple locations (e.g., two locations) around the circumference of the cylinder and hold the workpiece at their tips, and pin biasing means that biases the holding pins radially inward so that their tips protrude toward the inner periphery of the cylinder.

JP 2014-190215 A

In the workpiece assembly device of Patent Document 1, the retaining pins, which are spaced apart at two locations around the circumference of the cylindrical body, and the pin biasing means that bias the retaining pins radially inward, are arranged in a row along the diameter of the cylindrical body, necessitating the use of a cylindrical body that is thick in the radial direction. This makes it difficult to use the workpiece assembly device of Patent Document 1, for example, when assembling a lash adjuster as a workpiece into a recessed portion located deep within the cylinder block to which it is to be assembled. Therefore, the workpiece assembly device of Patent Document 1 is inevitably limited in its uses and has low versatility.

Furthermore, in the workpiece assembly device of Patent Document 1, the workpiece slides against the holding pins when it is attached to the holding section and when it is separated from the holding section (when the workpiece is assembled to the assembly target). Therefore, repeated use of the device can cause the holding pins to wear, potentially reducing the workpiece's holding power. For this reason, the holding pins need to be replaced periodically, but because the holding pins are arranged at multiple locations around the circumference of the cylindrical body and pin biasing means for biasing the holding pins are also arranged on the cylindrical body, replacing the holding pins (maintenance work for the holding section) requires time and cost.

The present invention was made to resolve various problems with known workpiece assembly devices (and their holding units). Its main purpose is to realize a holding unit that is compact and simple in configuration yet can properly hold a workpiece to be assembled to an assembly target, thereby contributing to improved versatility and maintainability of workpiece assembly devices.

The present invention, devised to achieve the above object, is a workpiece assembly device comprising a holding section that holds a workpiece and a pusher section that moves coaxially with the holding section relative to the holding section to push out the workpiece held in the holding section and assemble it onto an assembly target. The holding section comprises a cylindrical body into whose inner periphery the workpiece is inserted, and a retaining ring made of an elastic material and fitted around the outer periphery of the cylindrical body in an elastically expanded state. The portion of the cylindrical body into which the retaining ring is fitted has a notch that allows the retaining ring to partially protrude into the inner periphery of the cylindrical body, and the workpiece is held by the protruding portion of the retaining ring that protrudes into the inner periphery of the cylindrical body. The "elastic material" referred to here can be a soft material that is elastic (flexible), such as a rubber material or a thermoplastic elastomer.

In the workpiece assembly device of the present invention having the above configuration, the workpiece holding function achieved by the cooperation of the holding pins and pin biasing means incorporated inside the cylindrical body (arranged radially inside the cylindrical body) in the conventional workpiece assembly device described in Patent Document 1 is achieved by a holding ring made of an elastic material that is fitted around the outer periphery of the cylindrical body in an elastically expanded state. Therefore, according to the present invention, the radial thickness of the cylindrical body that constitutes the holding portion can be reduced to make the holding portion more compact, and the number of parts in the holding portion can be reduced to simplify the structure of the holding portion, allowing for easy and smooth maintenance work (replacement of the holding ring) to restore workpiece holding ability, etc.

In the above configuration, it is preferable to provide the notches (protrusions) at multiple locations spaced apart circumferentially. This allows the workpiece inserted into the inner circumference of the cylindrical body to be stably held by only the retaining ring made of an elastic material, effectively reducing the possibility of scratches or other defects being formed on the workpiece when the workpiece is attached to the holding section and when the workpiece held in the holding section is pushed out by the pushing section (assembling it onto the assembly target).

As explained above, the present invention makes it possible to realize a holding unit that is compact and simple in configuration yet can properly hold a workpiece to be assembled to an assembly target, thereby realizing a workpiece assembly device that is highly versatile and has excellent maintenance workability, etc.

1 is a schematic perspective view of a workpiece assembling device according to an embodiment of the present invention, in an initial state, as viewed obliquely from above and in front thereof; 1 is a schematic perspective view of the workpiece assembly device when the workpiece is attached to the attachment target, as viewed from diagonally above the front. FIG. 2 is a schematic cross-sectional view of the workpiece assembly device shown in FIG. 1 taken along the AA plane in the same figure. 1A and 1B are diagrams for explaining the process of mounting a workpiece on a workpiece assembly device, in which (a) is a diagram showing the start of the process, (b) is a cross-sectional view taken along line B-B in (a), (c) is a diagram showing an intermediate stage of the process, (d) is a cross-sectional view taken along line B-B in (c), (e) is a diagram showing the completion stage of the process, and (f) is a cross-sectional view taken along line B-B in (e). FIG. 10 is a diagram showing the start stage of the workpiece assembling process. FIG. 10 is a diagram showing an intermediate stage of a workpiece assembling process. FIG. 10 is a diagram showing the completed stage of the workpiece assembly process.

Embodiments of the present invention will be described below with reference to the drawings (Figs. 1 to 7).

The workpiece assembly device 1 of this embodiment, shown in Figure 1 and elsewhere, is installed (suspended) within an assembly line for automobile engines (here, an in-line three-cylinder engine) and is used to assemble a lash adjuster 20 (see Figure 4(a) and elsewhere)] into a recess 31 provided in a cylinder block 30 (see Figure 5 and elsewhere). Therefore, in this embodiment, the lash adjuster 20 and cylinder block 30 correspond to the "workpiece" and "object to be assembled," respectively, as defined in the present invention. The lash adjuster 20 is a functional component that constitutes the engine's valve mechanism in cooperation with the camshaft and rocker arm. It includes a cylindrical, bottomed adjuster body 21 housed in the recess 31 of the cylinder block 30, and a hollow plunger 22 positioned on the inner periphery of the adjuster body 21 and displacing axially.

The workpiece assembly device 1 comprises a linear rail member 2, a first support member 4 fixed to a predetermined position on the rail member 2 (the longitudinal center in the illustrated example), a pair of second support members 5 arranged on either side of the first support member 4 and sliding along the rail member 2, and three workpiece chucks 10, each capable of holding (chucking) a lash adjuster 20. The workpiece chucks 10 are supported by the first support member 4 and the pair of second support members 5, one each. Therefore, the workpiece assembly device 1 of this embodiment is capable of assembling three lash adjusters 20 to the cylinder block 30 at one time. Anti-slip parts 3 are fixed to both longitudinal ends of the rail member 2 and are engageable with the second support members 5 in the direction of movement. An operating handle 6 for the workpiece assembly device 1 is fixed to each second support member 5.

The following provides a detailed explanation of the work chuck 10 of the work assembly device 1, which has the characteristic configuration of the present invention. Note that the work chucks 10 supported by each support member 4, 5 basically have the same structure, so the explanation here will focus on the work chuck 10 supported by the second support member 5 as a representative example.

As shown in FIG. 3 , the work chuck 10 includes a holding portion 11 that holds the lash adjuster 20, and a push rod 12 that is coaxial with the holding portion 11 and can move up and down relative to the holding portion 11, and that pushes the lash adjuster 20 held by the holding portion 11 outward (downward) of the holding portion 11 as the push rod 12 moves downward relative to the holding portion 11 (to be assembled into a recess 31 in the cylinder block 30). The push rod 12 is fixed to the second support member 5 by fastening a nut to a thread formed on one longitudinal end (upper end) of the push rod 12, and a storage recess 12a is formed on the other longitudinal end (lower end) of the push rod 12 in which a portion of the lash adjuster 20 (plunger 22) is stored.

The retaining portion 11 comprises a cylindrical body 13 having a cylindrical tube portion 13a into whose lower end inner periphery (part of the lash adjuster 20) is inserted, and a flange portion 13b integrally formed with the tube portion 13a and projecting radially outward from the upper end of the tube portion 13a, and a retaining ring 14 fitted onto the outer periphery of the lower end of the tube portion 13a (the outer periphery of the portion into which the lash adjuster 20 is inserted). The retaining ring 14 is formed into an annular shape from an elastic material primarily composed of rubber or thermoplastic elastomer, and is fitted onto the outer periphery of the tube portion 13a in an elastically expanded state. The inner diameter of each axial portion of the portion of the tube portion 13a into which the lash adjuster 20 is inserted is set to be a predetermined amount larger than the outer diameter of the lash adjuster 20 (the portion of the lash adjuster 20 that is positioned on the inner periphery of the tube portion 13a). Therefore, when the lash adjuster 20 is inserted into the inner periphery of the lower end of the cylindrical portion 13a of the cylindrical body 13, the fit between the two is what is known as a loose fit (see JIS B 0401-1).

The work chuck 10 is attached to the outer periphery of the push rod 12 and further includes a spring member 15 interposed in a compressed state between the support member (second support member 5) and the flange portion 13b of the cylindrical body 13, and a guide shaft 16 whose one longitudinal end (upper end) is slidably inserted into the second support member 5 and whose other longitudinal end (lower end) is fixed to the flange portion 13b of the cylindrical body 13. Therefore, in this embodiment, the holding portion 11 forms the movable side of the work chuck 10, and the push rod 12 forms the stationary (fixed) side of the work chuck 10.

The portion of the cylindrical portion 13a of the cylindrical body 13 into which the retaining ring 14 is fitted is formed with an annular positioning portion 13c for positioning the retaining ring 14 (preventing misalignment of the retaining ring 14). As shown in Figures 4(b), 4(d), and 4(f), this positioning portion 13c is formed by arranging two arc-shaped circumferential grooves 13d formed on the outer surface of the cylindrical portion 13a and two notches 13e alternately in the circumferential direction, allowing a portion (a partial circumferential area) of the retaining ring 14 fitted into the positioning portion 13c to protrude toward the inner circumference of the cylindrical portion 13a of the cylindrical body 13.

Because the positioning portion 13c is formed on the cylindrical portion 13a of the cylindrical body 13, when the retaining ring 14 is fitted into the positioning portion 13c (fitted in a state where it is elastically expanded in diameter), the retaining ring 14 deforms into a generally elliptical shape, and protrusions 14a are formed on the retaining ring 14 that protrude radially inward beyond the inner circumferential surface of the cylindrical portion 13a [see Figure 4(b)]. The protrusions 14a are located at two opposing locations across the hollow portion of the cylindrical portion 13a, and the distance D between the opposing surfaces of the two protrusions 14a (the diameter of the inscribed circle tangent to the inner diameter end of each protrusion 14a) is set to be smaller than the diameter of the portion of the lash adjuster 20 that faces the retaining ring 14 (protrusions 14a) when the lash adjuster 20 is held by the retaining portion 11. With the above configuration, when the lash adjuster 20 is held by the holding portion 11, the lash adjuster 20 is held by the protruding portion 14a of the retaining ring 14 without contacting the cylindrical portion 13a of the cylindrical body 13 [see Figures 4(e) and (f)].

The assembly of the lash adjuster 20 to the cylinder block 30 using the work assembly device 1 configured as described above is performed as follows. The assembly of the lash adjuster 20 is performed by a worker engaged in assembly work on an engine assembly line manually operating the work assembly device 1 while grasping the operating handles 6 fixed to each of the pair of second support members 5.

First, as shown in FIG. 1, the work assembly device 1 is placed in its initial state, with the pair of second support members 5 abutting the first support member 4. In this initial state, the work chucks 10 supported by each support member 4, 5 are arranged at regular intervals. Next, the work assembly device 1 in its initial state is operated to hold the lash adjusters 20 in the holding portions 11 of each work chuck 10.

The lash adjuster 20 is held by the holding portion 11 in the following manner.
First, as shown in Figure 4(a), the holding portions 11 provided on each work chuck 10 are arranged coaxially with the lash adjusters 20 aligned at regular intervals in a parts box in a vertical position (upright position) with the adjuster bodies 21 arranged on the bottom side, and then the work assembly device 1 is moved downward and the lash adjusters 20 are inserted into the inner periphery of the lower end of the cylindrical portion 13a of the cylindrical body 13. As the downward movement of the work assembly device 1 progresses and the lash adjusters 20 are inserted into the inner periphery of the cylindrical portion 13a, the portion of the retaining ring 14 fitted on the outer periphery (positioning portion 13c) of the cylindrical portion 13a is pushed radially outward, elastically deforming the retaining ring 14 [see Figures 4(c) and 4(d)].

Then, as shown in Figure 4(e), when the lower end of the push rod 12 abuts against the upper end surface of the adjuster body 21 and the plunger 22 protruding upward from the adjuster body 21 is accommodated in the accommodation recess 12a of the push rod 12, the elastic restoring force displaces the protruding portion 14a of the retaining ring 14 radially inward, causing the protruding portion 14a to abut against the outer peripheral surface of the lash adjuster 20 (adjuster body 21), as shown in Figure 4(f). This causes the lash adjuster 20 to be held by the holding portion 11 of each work chuck 10.

The workpiece assembly device 1, with the lash adjusters 20 held by each holding portion 11 in the above manner, is then moved upward away from the parts box in which the lash adjusters 20 are aligned, and is then positioned above the cylinder block 30 to which the lash adjusters 20 are to be assembled, as shown in Figure 5. At this time, the second support member 5 is slid along the rail member 2 (see Figure 2), so that the holding portion 11 of each workpiece chuck 10 is positioned above the corresponding recesses 31 provided at predetermined intervals in the cylinder block 30.

As shown in Figure 5, a spacer 32 is placed on the cylinder block 30, and a guide member 33 is installed on the spacer 32 at a location adjacent to an extension of the center line of the recess 31. The guide member 33 guides the retaining portion 11 (cylindrical body 13) inserted into the cylinder block 30 when the lash adjuster 20 is installed in the recess 31 located deep in the cylinder block 30. The guide member 33 is provided with a stopper portion 34 that engages with the workpiece assembly device 1 in the insertion direction of the retaining portion 11.

Then, as shown in Figures 5 and 6, while guiding the holding portion 11 (cylindrical body 13) with the guide member 33, the workpiece assembly device 1 is moved downward until the flange portion 13b of the cylindrical body 13 engages with the guide member 33. When the flange portion 13b of the cylindrical body 13 engages with the guide member 33, a portion of the lash adjuster 20 held by the holding portion 11 (the portion protruding below the holding portion 11) is inserted into the recess 31.

7, when the workpiece assembly device 1 is further moved downward from the above state until it engages with the stopper portion 34 of the guide member 33, the holding portion 11 (cylindrical body 13) moves upward against the elastic restoring force of the spring member 15, and the push rod 12 moves downward relative to the holding portion 11. When the push rod 12 moves downward relative to the holding portion 11, the lash adjuster 20 engaged with the push rod 12 (the plunger 22 is housed in the housing recess 12a of the push rod 12) also moves downward relative to the holding portion 11. As a result, the protruding portion 14a of the retaining ring 14, which had been abutting the outer peripheral surface of the lash adjuster 20, elastically deforms radially outward, and the lash adjuster 20 is released from the holding state of the holding portion 11. Therefore, when the workpiece assembly device 1 is moved upward, the lash adjuster 20 is pushed outward (downward) from the holding portion 11 and assembled into the recess 31 of the cylinder block 30.

To summarize the characteristic configuration of the workpiece assembly device 1 described above, the holding portion 11 that holds the lash adjuster 20 as workpiece comprises a cylindrical body 13 into whose inner periphery the lash adjuster 20 is inserted (loose fit), and a retaining ring 14 formed in an annular shape from an elastic material such as rubber and fitted onto the outer periphery of the cylindrical body 13 in an elastically expanded diameter state. The portion of the cylindrical body 13 (cylindrical portion 13a) into which the retaining ring 14 is fitted has a notch 13e that allows the retaining ring 14 to partially protrude into the inner periphery of the cylindrical portion 13a of the cylindrical body 13, and the lash adjuster 20 is held by the protruding portion 14a of the retaining ring 14 that protrudes into the inner periphery of the cylindrical portion 13a.

In other words, in the workpiece assembly device 1 of this embodiment, the workpiece holding function, which was previously achieved by the cooperation of the holding pins and pin biasing means incorporated inside the cylindrical body (arranged radially inside the cylindrical body) in the conventional workpiece assembly device described in Patent Document 1, is achieved by the retaining ring 14 made of an elastic material that is fitted around the outer periphery of the cylindrical portion 13a of the cylindrical body 13 in an elastically expanded state. Therefore, according to the present invention, the radial thickness of the cylindrical portion 13a of the cylindrical body 13 that constitutes the holding portion 11 can be reduced to make the holding portion 11 more compact, and the number of parts of the holding portion 11 can be reduced to simplify the structure of the holding portion 11, allowing for easy and smooth maintenance work (replacement of the retaining ring 14) to restore the holding ability of the workpiece (lash adjuster 20), etc.

In particular, in this embodiment, the notches 13e provided in the cylindrical body 13 are spaced equally apart in the circumferential direction, and therefore the protrusions 14a of the retaining ring 14 are also spaced equally apart in the circumferential direction. In this way, the lash adjuster 20, which is inserted (loose fit) into the inner circumference of the cylindrical portion 13a of the cylindrical body 13, can be stably held by only the retaining ring 14 made of an elastic material. This effectively reduces the possibility of defects such as scratches being formed in the lash adjuster 20 when the lash adjuster 20 is attached to the retaining portion 11, and when the lash adjuster 20 held in the retaining portion 11 is pushed out by the push rod 12.

As described above, the present invention makes it possible to realize a holding portion 11 that is compact and simple in configuration yet can properly hold the lash adjuster 20, thereby enabling the realization of a highly versatile workpiece assembly device 1 with excellent maintenance workability, etc., at low cost.

The above describes the workpiece assembly device 1 according to one embodiment of the present invention and the method for using it to assemble a workpiece (lash adjuster 20) to an assembly target, but the present invention is not limited to this embodiment.

For example, the notches 13e provided in the cylindrical body 13 that constitutes the holding portion 11 can be provided in three or more locations around the circumference of the cylindrical body 13. Furthermore, the workpiece assembly device 1 can be used not only when assembling the lash adjuster 20 into the recess 31 of the cylinder block 30, which is its assembly target, but also when assembling other workpieces to the assembly target. Furthermore, the workpiece assembly device 1 can also be attached to automated equipment such as a robot arm for use.

1 Workpiece assembly device 10 Workpiece chuck 11 Holding part 12 Push-out rod (pushing part)
13 Cylinder 13a Cylinder portion 13c Positioning portion 13d Circumferential groove 13e Notch 14 Retaining ring 14a Protrusion 20 Lash adjuster (workpiece)
30 Cylinder block (mounting target)
31 recess

Claims (2)

A workpiece assembling device including a holding unit that holds a workpiece, and a push-out unit that moves coaxially with the holding unit relative to the holding unit to push out the workpiece held by the holding unit and assemble it to an assembly target,
the holding portion includes a cylindrical body into whose inner periphery the workpiece is inserted, and a holding ring formed in an annular shape from an elastic material and held on the outer periphery of the cylindrical body in an elastically expanded state;
A work assembly device characterized in that a notch is provided in the portion of the cylindrical body into which the retaining ring is fitted to allow the retaining ring to partially protrude into the inner circumference of the cylindrical body, and when the outer surface of the workpiece is held in contact with and held by the protruding portion of the retaining ring that protrudes into the inner circumference of the cylindrical body through the notch, the workpiece is not in contact with the cylindrical body . The workpiece assembly device according to claim 1, wherein the notches are provided at multiple locations spaced apart circumferentially.