FIELD OF INVENTION:

This invention relates to a method and apparatus for assembling bearings on a crankshaft assembly, particularly a crankshaft assembly for an internal combustion engine. The invention particularly relates to a method and apparatus for assembling bearings on both the left hand side (crankshaft LHS) and right hand side (crankshaft RHS) of a crankshaft assembly.

BACKGROUND TO THE INVENTION

In an internal combustion (IC) engine, the crankshaft assembly generally comprises two halves or portions, namely a crankshaft LHS and a crankshaft RHS, which are connected to each other through a crank pin. The crank pin is connected to one end of a connecting rod, the other end of the connecting rod being connected to a piston. The crankshaft LHS and crankshaft RHS each have a shaft portion of suitable diameter on which a bearing may be mounted. The inner diameters of bearings are fitted on these portions of the shafts and the outer diameters are then fitted into respective crankcase halves. The bearings are fitted onto the crankshaft in a press fit.

Conventionally, the bearings are fitted on each of the crankshaft LHS and crankshaft
RHS portions using separate adapters in a manual operation. The operation of fitting bearings is carried out in different stages or separate steps. During a first step, a threaded portion on one side of the crankshaft is fitted to an adapter. This side is then placed within a bearing located on a bearing holder. The crankshaft is pulled downwardly with a puller mechanism through the bearing to fit it on the crankshaft. The crankshaft assembly is then reversed in position by the operator and the above process is carried out to fit a bearing on the other side of the crankshaft assembly. Subsequent to assembly of bearings on both sides of the crankshaft assembly, run-out checking/inspection is carried out.

The above described assembly method requires significant cycle time for assembling bearings on the crankshaft assembly as, in every cycle/operation, the crankshaft must be positioned twice or even multiple times by the operator. This repetitive manual operation induces fatigue in the operator performing the bearing assembly operations.

The run-out checking/inspection of the crankshaft assembly subsequent to assembly of bearings is an' essential operation. It may be understood that, in the above method of assembly, typically in mass production set up, the run-out checking/inspection of the crankshaft assembly must necessarily be carried out by another or second operator as the first operator has to start his initial work of fitting the adapter on to another crankshaft assembly to keep ready for the next cycle. This calls for additional manpower for checking run-out.

An object of the present invention is to provide a method and apparatus for assembling bearings on a crankshaft assembly which has reduced cycle time and which induces less operator fatigue. Manpower utilisation may also be improved.

SUMMARY OF THE INVENTION

With this object in view, there is provided - in accordance with a first aspect of the invention - a method for assembling bearings on a crankshaft assembly, the method comprising the steps of locating the crankshaft assembly within a holding device, the holding device being moveable in at least two directions; positioning at least two bearings relative to respective bearing locators; and moving the holding device in a first direction in order to fit a first bearing to the crankshaft assembly and moving the holding device in a second direction to fit a further bearing to the crankshaft assembly.

Preferably, the two directions are aligned with a longitudinal axis of the crankshaft assembly, with one direction oriented towards the crankshaft LHS and the other direction oriented towards the crankshaft RHS.

The holding device may be moved, for example by mechanical or hydraulic means, from the first direction to the second direction at speed dictated by the operator or within a predetermined time if the movement operation is automated.

According to a second aspect of the invention, there is provided an apparatus for mounting bearings on a crankshaft assembly, the apparatus comprising at least a pair of bearing locators for positioning of respective bearings; and a crankshaft assembly holding device wherein said crankshaft assembly holding device is bi-directionally movable in respective first and second directions enabling sequential movement of the holding device between each of the bearing locators for fitting of the bearings to the crankshaft assembly.

Preferably, the two directions of movement are aligned with a longitudinal axis of the crankshaft assembly, with one direction oriented towards the crankshaft LHS and the other direction oriented towards the crankshaft RHS. The apparatus allows fitting of bearings to the respective halves or portions of the crankshaft assembly.

The apparatus, and more particularly the crankshaft assembly holding device, may allow the crankshaft assembly to be moved in upward and downward directions to enable fitting of bearings to respective halves or portions of the crankshaft assembly. Such movement of the crankshaft assembly may be achieved by a hydraulic press, for example a double acting press. In such case, movement of the crankshaft assembly may be caused by a hydraulic ram, the travel of the ram being so adjusted as to achieve press fitting of bearings on the crankshaft assembly.

The apparatus may be provided with limit switch(es) to ensure or provide an indication of the completion of movement of the holding device in a respective direction.

Preferably, the bearing locators are respectively positioned to correspond with upper and lower ends of the crankshaft assembly holding device. The upper bearing locator may be provided with a locking arrangement to ensure that the crankshaft assembly is securely located for fitting of bearings. It will be appreciated that such location is advantageous for reproducible fitting of bearings within a required tolerance.

The method and apparatus for assembling bearings on a crankshaft assembly as above described enables bearings to be fitted on crankshaft LHS and crankshaft RHS portions using only one setting step. In addition, the same operator may perform run-out checking of the crankshaft assembly or other work while the bearing assembly operation is being performed.

BRIEF DESCRIPTION OF THE DRAWINGS

The method and apparatus for assembling bearings on a crankshaft assembly in accordance with the invention may be more fully understood from the following non-limiting description of a [preferred embodiment thereof made with reference to
the following drawings in which:

Fig. 1 illustrates a plan view of a crankshaft assembly ready for bearing fitment in accordance with the prior art.

Figs 2a, 2b and 2c. illustrate stages/steps of assembling bearings on a crankshaft assembly in accordance with the prior art.

Fig. 3 illustrates an apparatus for assembling bearings on a crankshaft assembly in accordance with one embodiment of the present invention.

Fig. 4 illustrates the same apparatus as shown in Fig. 3 but with the crankshaft assembly holding device being located to have a bearing fitted to a first half or portion of a crankshaft assembly.

Fig. 5 illustrates the same apparatus as shown in Figs. 3 and.4 but with the
crankshaft assembly holding device being located to have a bearing fitted to the
second half or portion of the crankshaft assembly.

Figs. 1, 2a, 2b and 2c depict different stages in a method for assembling bearings on a crankshaft according to the prior art. During the first step, a threaded portion on one side, being the LHS portion or half, of a crankshaft assembly (10) is engaged with an adapter (1,j1). This side (10a) of the crankshaft assembly (10) is then manually positioned in a bearing holding device or holder (12) having a bearing (13) placed on it. The crankshaft assembly (10), engaged with the adapter (11), is then pulled downwardly with a puller mechanism (14) across the bearing (13) to fit it on the crankshaft bearing diameter. The puller mechanism (14) is a well known mechanism and hence does not require detailed explanation. The crankshaft assembly (10) is then manually reversed in position and the same process is carried out to fit another bearing on to the other side (1 0b) of the crankshaft assembly (10). Subsequent to assembly of bearings on both sides of the crankshaft assembly (10), run-out checking/inspection is carried out.

It may be understood that the above described bearing assembly method requires significant cycle time as in every cycle/operation, the crankshaft assembly (10) is required to be manually positioned two times by an operator. This process is laborious and readily induces fatigue in the operator performing it. In a mass production set-up, the run-out checking/inspection of the crankshaft assembly (10) -subsequent to bearing fitting - must be performed. It can be observed that, with the above assembly method, this operation needs to be carried out by a different or second operator as the first operator has to start his initial work of engaging the adapter (11) to another crankshaft and be ready for the next bearing assembly cycle. This calls for additional manpower and increases operating expenses.

Referring now to Figs. 3 to 5 which depict assembly of bearings on a crankshaft assembly according to a preferred embodiment of the invention, the crankshaft assembly (100) is positioned, and suitably locked into position, within a crankshaft holding device in the form of platform (101) of a double acting or bidirectionally movable hydraulic press (102) which can travel upwardly and downwardly to enable fitting of bearings to the respective halves or portions of the crankshaft assembly. The movement of the hydraulic press (102) may also be automated as will be described below. Bearing (103) is positioned on a lower bearing locator in the form of lower plate (104) fitted on to a bottom platform (105) of the hydraulic press (102).

Another bearing (106) is located inside an upper bearing locator in the form of upper plate (107) with the help of spring ball type locating arrangement (120). The upper plate (107) is fitted on to the top platform (108) of the hydraulic press (102). The upper plate (107) and lower plate (104) are hardened plates, for example being chrome hardened.

When an operator operates the hydraulic press (102), which is provided with a double solenoid hydraulic valve system, say a 5/3 hydraulic valve operation system (not shown), the ram (130) of the press (102) is moved downwardly toward a base of the press (102).

The movement of the ram (130) causes a simultaneous movement of the crankshaft assembly (100) in the same downward direction. The ram (130) movement is stopped against a bottom dead stopper (109) of the hydraulic press (102). The travel of the ram (130) between mean or home position and bottom dead stopper (109) is so adjusted as to move crankshaft assembly (100) downwardly to assemble or fit the bearing (103) on the bearing diameter marked as 110 on say the right hand side of crankshaft assembly (100). In this way, a bearing (103) is press fitted on the crankshaft RHS half or portion. A limit switch may be provided to ensure or provide an indication of the completion of the downward stroke of the ram of press (102).

Subsequent to completion of the above mentioned first stroke, followed by some predetermined time delay (say 3 to 4 seconds), the ram (130) is moved upwardly or retracted. The ram (130) movement in this upward stroke is stopped against a top dead stopper (111) of the hydraulic press (102). The travel of the ram (130) between mean or home position and top dead stopper (111) is so adjusted as to move crankshaft assembly (100) upwardly to assemble or fit the bearing (106) on the bearing diameter marked as 112 on say the left hand side of crankshaft assembly (100). In this way, a bearing (106) is press fitted on the crankshaft LHS half or portion. Again, a limit switch may be provided to ensure or provide an indication of the completion of the upward stroke of the ram of press (102).

After completion of the upward stroke, the ram (130) returns to home or mean position. A predetermined time delay (say 3 to 4 seconds) may be provided after completion of the upward stroke of the ram (130). The crankshaft assembly (100) is unloaded and sent to the next operation, typically the run-out checking/inspection step.

From the above description, it may be observed that manual involvement of the operator is minimized. There is no need for the operator to unload the crankshaft assembly from the hydraulic press (102) and position the crankshaft assembly (100) twice or a multiple of times. During the assembly of bearings to crankshaft assembly (100), the operator can perform other tasks including run-out checking of crankshaft assemblies fitted with bearings in previous assembly cycles. This leads to effective manpower utilisation. Therefore, the method and apparatus of the invention completes the bearing assembly operation in reduced time with less fatigue to the operator than the prior art.

Modifications and variations to the method and apparatus for assembling a bearing to a crankshaft assembly as described herein may be apparent to the skilled reader of this disclosure. Such modifications and variations are deemed to be within the scope of the present invention.

WE CLAIM:

1. A method for assembling bearings on a crankshaft assembly, the method comprising the steps of locating the crankshaft assembly within a holding device, the holding device being moveable in at least two directions; positioning at least two bearings relative to respective bearing locators; and moving the holding device in a first direction in order to fit a first bearing to the crankshaft assembly and moving the holding device in a second direction to fit a further bearing to the crankshaft assembly.

2. The method of claim 1 wherein the two directions are aligned with a longitudinal axis of the crankshaft assembly, with one direction oriented towards the crankshaft LHS and the other direction oriented towards the crankshaft RHS.

3. The method of claim 1 or 2 wherein the holding device is moved from the first direction to the second direction at speed dictated by the operator or within a predetermined time if the movement operation is automated.

4. An apparatus for mounting bearings on a crankshaft assembly, the apparatus comprising at least a pair of bearing locators for positioning of respective bearings; and a crankshaft assembly holding device wherein said crankshaft assembly holding device is bi-directionally moveable in respective first and second directions enabling sequential movement of the holding device between each of the bearing locators for fitting of the bearings to the crankshaft.

5. The apparatus of claim 4 wherein the two directions are aligned with a longitudinal axis of the crankshaft assembly, with one direction oriented towards the crankshaft LHS and the other direction oriented towards the crankshaft RHS.

6. The apparatus of claim 4 or 5 wherein the holding device allows the crankshaft assembly to be moved in upward and downward directions to enable fitting of bearings to the crankshaft assembly.

7. The apparatus of any one of claims 4 to 6 being a hydraulic press with a ram to cause movement of the crankshaft assembly, the travel of the ram being so adjusted as to achieve press fitting of bearings on the crankshaft assembly.

8. The apparatus of any one of claims 4 to 7 having a limit switch to ensure or provide an indication of the completion of movement of the holding device in a respective direction.

9. The apparatus of any one of claims 4 to 8 wherein said bearing locators are respectively positioned to correspond with upper and lower ends of the crankshaft assembly holding device.

10. The apparatus of claim 9 wherein the upper bearing locator comprises a locking arrangement to ensure that the crankshaft assembly is securely located for fitting of bearings.

11. A method for assembling bearings on a crankshaft assembly substantially as hereinbefore described with reference to Figs. 3 to 5.

12. An apparatus for assembling bearings on a crankshaft assembly substantially as hereinbefore described with reference to Figs. 3 to 5.