This application claims priority to Great Britain Patent Application No. 1520897.8, filed Nov. 26, 2015, the entire contents of which are hereby incorporated by reference for all purposes.
This disclosure relates to a method of locating a balancer shaft bearing of an engine, so as to restrict the movement of the balancer shaft bearing.
A balancer shaft for an engine is typically located within the engine casing, for example the balancer shaft may be assembled into a ladder frame casing of the engine. The balancer shaft can be mounted on balancer shaft bearings, which can each be secured in place on the ladder frame using a bearing cap, for example a ladder frame cap. The front and rear balancer shaft bearings are usually located at the front and rear ladder frame cap positions respectively.
In many examples, the balancer shaft bearing is a roller bearing assembly. In some circumstances the inner race of the balancer shaft bearing is press fit onto the balancer shaft so that the bearing defines the position of the balancer shaft when the balancer shaft is assembled into the ladder frame casing of the engine. It is desirable therefore to locate the balancer shaft bearing relative to the engine casing to ensure that the balancer shaft is accurately positioned.
In order to simplify the assembly procedure, the outer race of the roller bearing may be free to move axially relative to the inner race. As such, it is desirable to locate accurately the outer race of the balancer shaft bearing.
According to an aspect of the present disclosure there is provided a method of locating a balancer shaft bearing of an engine, the method comprising the steps of: attaching a bearing retention clip to a balancer shaft bearing cap thereby defining a balancer shaft bearing cap assembly, the bearing retention clip comprising one or more retaining elements that extend at least partially across an opening, for example a cut-out, of the balancer shaft bearing cap in an installed configuration; subsequently assembling the balancer shaft bearing cap and the balancer shaft bearing such that a portion of the balancer shaft bearing is received in the opening of the balancer shaft bearing cap and such that the movement of the balancer shaft bearing is restricted relative to the balancer shaft bearing cap upon engagement of the balancer shaft bearing with one or more of the retaining elements of the bearing retention clip. In this manner, the present disclosure provides a method for locating the balancer shaft bearing by restricting the movement of the balancer shaft bearing relative to the balancer shaft bearing cap. The balancer shaft bearing cap assembly, i.e. the bearing retention clip in combination with the balancer shaft bearing cap, may be used to position accurately the balancer shaft bearing relative to an engine casing. A further advantage is that the balancer shaft bearing cap assembly may be used to prevent the balancer shaft bearing becoming displaced from a bearing seat during operation of the engine.
The method may comprise assembling the balancer shaft bearing onto a balancer shaft, thereby defining a balancer shaft assembly. The method may comprise assembling, for example rigidly fixing at least a portion of the balancer shaft bearing, for example an inner race of the balancer shaft bearing, onto the balancer shaft.
The method may comprise assembling the balancer shaft assembly into an engine casing, such that at least a portion of the balancer shaft bearing is disposed in the opening of a wall of the engine casing. The method may comprise locating the balancer shaft assembly relative to the engine casing using the bearing retention clip upon assembling the balancer shaft bearing cap to the engine casing. The bearing retention clip may be used to locate the axial position of the balancer shaft assembly upon initial assembly into the engine casing, for example before the bearing cap is secured in position. In this manner, the position of the balancer shaft bearing may determine the position of the balancer shaft assembly once the bearing cap is secured in position. The present disclosure may provide a method for locating the balancer shaft bearing during assembly of the engine.
The method may comprise assembling a first balancer shaft bearing and a second balancer shaft bearing onto the balancer shaft. The first balancer shaft bearing may be radially and/or axially constrained relative to the balancer shaft. The first balancer shaft bearing may be secured to the balancer shaft such that the position of the balancer shaft within an engine casing may be defined by the position of the first balancer shaft bearing. The second balancer shaft bearing may be radially constrained and axially movable relative to the balancer shaft. A first portion of the second balancer shaft bearing may be rigidly fixed to the balancer shaft and a second portion of the second balancer shaft bearing may be movable with respect to the first portion of the second balancer shaft bearing. For example, the second balancer shaft bearing may comprise an inner race rigidly fixed to the balancer shaft and an outer race that is movable, for example axially and/or radially moveable, with respect to the inner race.
The method may comprise assembling the balancer shaft assembly into the engine casing. The method may comprise locating the balancer shaft assembly relative to the engine casing using a first balancer shaft bearing cap assembly, for example by virtue of one or more retaining elements of the bearing retention clip. The method may comprise locating the second balancer shaft bearing relative to the balancer shaft using a second balancer shaft bearing cap assembly. For example, the method may comprise locating the movable outer race relative to the inner race of the second balancer shaft bearing.
According to another aspect of the present disclosure there is provided a balancer shaft bearing cap assembly for a balancer shaft bearing of an engine, the balancer shaft bearing cap assembly comprising: a balancer shaft bearing cap having an opening configured to receive at least a portion of the balancer shaft bearing; and a bearing retention clip configured to attach to the balancer shaft bearing cap, the bearing retention clip comprising one or more retaining elements that extend at least partially across the opening of the balancer shaft bearing cap in an installed configuration, the one or more retaining elements each being configured to engage and restrict the movement of the balancer shaft bearing relative to the balancer shaft bearing cap when the balancer shaft bearing is received in the opening of the balancer shaft bearing cap, the balancer shaft bearing being receivable in the opening of the balancer shaft bearing cap when the bearing retention clip is attached to the balancer shaft bearing cap.
The balancer shaft bearing cap may be used to secure the balancer shaft bearing to an engine casing. The retaining elements may be configured to engage an axial end face of the balancer shaft bearing. The retaining elements may be configured to restrict the movement of the balancer shaft bearing in a direction defined by the longitudinal axis of a balancer shaft of the engine. The retaining elements may extend towards the longitudinal axis of the balancer shaft. In an example where the retention clip comprises more than one retaining element, each retaining element may be different in shape and/or size, for example each retaining element may extend across the opening in the balancer shaft bearing cap by different amounts and/or in different directions.
The balancer shaft bearing cap assembly may be configured to locate axially the balancer shaft bearing and/or the balancer shaft relative to the balancer shaft bearing cap and/or the engine casing. The balancer shaft bearing cap assembly may be used as an alignment aid, for example the balancer shaft bearing cap assembly may be used to help align the balancer shaft bearing in relation to the engine casing during an assembly operation.
The engine casing may comprise an engine casing wall, for example a ladder frame wall. The balancer shaft bearing cap assembly may be attachable to a portion of the engine casing, for example the ladder frame wall. The engine casing wall may comprise an opening, for example a cut-out. The opening in the engine casing wall may form at least a portion of a bearing seat configured to receive the balancer shaft bearing. The opening in the bearing cap and the opening in the engine casing wall may form a bore in which the balancer shaft bearing may be secured in an assembled configuration.
The opening in the bearing cap may form at least a portion of a bearing seat configured to receive the balancer shaft bearing. In one example, each retaining element may at least partially extend over an edge of the opening in which the bearing is seated.
The balancer shaft bearing cap assembly may be configured such that there is a gap between one or more of the retaining elements and the balancer shaft bearing in an installed configuration. The gap may be sufficient to allow for the stack-up of any appropriate assembly tolerances. The gap may be provided to allow for the thermal expansion of components. The gap may be selected in accordance with the configuration of the engine, for example different gap sizes may be appropriate for different bearing retention clips and/or different engines depending upon the configuration of the balancer shaft bearing, the engine casing, the bearing cap and/or the balancer shaft. The gap may be approximately 0.15 mm.
The balancer shaft bearing may comprise a bearing assembly, for example a rolling element bearing assembly. The rolling element bearing assembly may comprise an outer race and/or an inner race. The balancer shaft bearing cap assembly may be configured to restrict the axial movement of the outer race and/or the inner race of the rolling element bearing assembly. The retaining elements may be configured to engage the outer race and/or the inner race of the rolling element bearing assembly. The inner race of the bearing assembly may be rigidly fixed to the balancer shaft. The inner race of the balancer shaft bearing may be an interference fit on the balancer shaft. The bearing assembly may be a self-constrained bearing assembly, i.e. the inner race and the outer race of the bearing are unable to move axially with respect to each other. The bearing assembly may be an unconstrained bearing assembly, i.e. the inner race and the outer race of the bearing are able to move axially with respect to each other.
The balancer shaft bearing cap assembly may be configured to restrict the axial movement of the inner race and/or the outer race of the rolling element bearing assembly, for example within a predetermined range of movement.
The bearing retention clip may comprise a first retaining element configured to restrict the movement of the balancer shaft bearing in a first direction. The bearing retention clip may comprise a second retaining element configured to restrict the movement of the balancer shaft bearing in a second direction with at least a component that is opposite to the first direction.
The bearing retention clip may comprise a body portion configured to engage and be attached to the balancer shaft bearing cap. The retaining element of the bearing retention clip may be attachable to a body portion of the bearing retention clip. The body portion of the bearing retention clip may be attachable to the balancer shaft bearing cap.
The balancer shaft may extend though the balancer shaft bearing. An end of the balancer shaft may be coupled to pulley wheel or a gear, which may be used to drive an ancillary device of the engine, for example a motor-generator or any other appropriate device.
The engine may comprise one or more of the balancer shaft bearing cap assemblies.
To avoid unnecessary duplication of effort and repetition of text in the specification, certain features are described in relation to only one or several aspects or arrangements of the disclosure. However, it is to be understood that, where it is technically possible, features described in relation to any aspect or arrangement of the disclosure may also be used with any other aspect or arrangement of the disclosure.
For a better understanding of the present disclosure, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:
The figures are drawn to scale, although other relative dimensions may be used, if desired.
The balancer shaft 103 may be coupled to, for example rotatably mounted in, one or more balancer shaft bearings 105a, 105b such that the balancer shaft 103 may rotate with respect to the engine casing 101. In the example shown in
In the example shown in
In a similar manner to the front and rear walls 107a, 107b of the ladder frame casing, the front and rear bearing caps 111a, 111b each have an opening 113a, 113b, for example a cut-out, configured to receive a portion of the front and rear bearings 105a, 105b respectively. Thus, in an assembled configuration, the front bearing 105a is seated in a bore, for example a substantially circular bore, that is formed by the openings 109a, 113a in the front ladder frame wall 107a and the front bearing cap 111a respectively. The rear bearing 105b is seated in a bore, for example a substantially circular bore, that is formed by the openings 109b, 113b in the rear ladder frame wall 107b and the rear bearing cap 111b respectively.
The front and rear bearings 105a, 105b are radially secured to the ladder frame walls 107a, 107b using the front and rear bearing caps 111a, 111b, for example front and rear ladder frame caps. The bearing caps 111a, 111b are configured to be attached to, for example removably attached to, the walls 107a, 107b using one or more fasteners. Dowel pins, or any other appropriate means, may be used to position the front and rear bearing caps 111a, 111b relative to the front and rear walls 107a, 107b of the ladder frame casing. In this manner, the dowel pins serve to align the opening 109a, 109b in the front and rear walls 107a, 107b with the opening 113a, 113b in the front and rear bearing caps 111a, 111b.
In an assembled configuration, the front and rear bearings 105a, 105b are clamped in position using the bearing caps 111a, 111b. It is desirable to control the axial position of the balancer shaft bearing 105a, 105b accurately during assembly, to ensure that the balancer shaft bearing 105a, 105b, and therefore the balancer shaft 103 are positioned accurately within the engine casing 101.
The rear end 103b of the balancer shaft 103 is assembled into the inner race 115b such that the rear end 103b of the balancer shaft 103 is rigidly fixed in the inner race 115b. For example, the rear end 103b of the balancer shaft 103 may be press-fitted into the inner race 115b of the rear bearing 105b. In the example shown
b show a balancer shaft bearing cap assembly 122a, 122b comprising the bearing retention clip 123a, 123b and the bearing cap 111a, 111b. In
The bearing retention clip 123a, 123b comprises one or more retaining elements 125 that at least partially extend across the opening 113a, 113b of the bearing cap 111a, 111b when the bearing retention clip 123a, 123b is attached to the bearing cap 111a, 111b. In the examples shown in
Each of the retaining elements 125 is configured to engage an axial end face 126 of the balancer shaft bearing 105a, 105b and restrict the movement of the balancer shaft bearing 105a, 105b when assembling the bearing cap 111a, 111b to the engine casing 101. In this manner, the balancer shaft bearing 105a, 105b is axially located relative to the bearing cap 111a, 111b and the engine casing 101. In the examples of
In the examples of
As shown in
In another example, the bearing retention clip 123a, 123b may be planar in form and may comprise a retaining element 125 that is configured to be attached to an axial end face of the bearing cap 111a, 111b, for example a front face 131 or a rear face 133 of the bearing cap 111a, 111b. In a further example, the retaining element 125 may comprise one or more protrusions or ridges that are configured to extend into the opening and engage the bearing 105a, 105b, for example an axial end face 126 of the outer race 117a, 117b of the bearing 105a, 105b.
The present disclosure provides a method 100 of locating a balancer shaft bearing 105a, 105b of an engine, for example a method of locating the balancer shaft bearing 105a, 105b in relation to the bearing cap 111a, 111b and/or the wall 107a, 107b of the engine casing 101. The method comprises a step 110 of attaching the bearing retention clip 123a, 123b to the bearing cap 111a, 111b such that at least one retaining elements 125 of the bearing retention clip 123a, 123b extends across the opening 113a, 113b in the bearing cap 111a, 111b, thereby defining the balancer shaft bearing cap assembly 122a, 122b. The bearing cap 111a, 111b and the bearing 105a, 105b are assembled at step 120 such that a portion of the bearing 105a, 105b is received in the opening 113a, 113b of the bearing cap 111a, 111b. The method comprises a step 130 of restricting the movement, for example the axial movement, of the bearing 105a, 105b relative to the bearing cap 111a, 111b upon engagement of the bearing 105a, 105b with one or more of the retaining elements 125 of the bearing retention clip 123a, 123b.
The method 100 may further comprise assembling one or more of the bearings 105a, 105b onto the balancer shaft 103 such that the inner race 115a, 115b of the bearing 105a, 105b is rigidly fixed to the balancer shaft 103, thereby defining a balancer shaft assembly. The balancer shaft assembly may comprise; the balancer shaft 103; and at least a portion of the bearing 105a, 105b, for example the inner race 115a, 115b of the bearing 105a, 105b. The method 100 may comprise assembling the balancer shaft assembly into the engine casing 101, subsequently assembling the bearing cap 111a, 111b to the engine casing 101 such that a portion of the bearing 105a, 105b is received in the opening 113a, 113b of the bearing cap 111a, 111b, and locating the balancer shaft assembly relative to the engine casing 101 using the bearing retention clip 123a, 123b attached to the bearing cap 111a, 111b. In this manner, the axial position of the bearings 105a, 105b and the balancer shaft assembly are defined by the bearing retention clip 123a, 123b in an assembled configuration.
In one example, the bearing retention clip 123a, 123b may be secured to the bearing cap 111a, 111b prior to the bearing cap 111a, 111b being assembled to the wall 107a, 107b of the engine casing 101. In such an example, during assembly of the bearing cap 111a, 111b to the wall 107a, 107b of the engine casing 101, the bearing 105a, 105b is received in the opening 113a, 113b of the bearing cap 111a, 111b and is axially located within the opening 113a, 113b by the retaining elements 125. In another example, however, the bearing retention clip 123a, 123b may be secured to the bearing cap 111a, 111b after the bearing cap 111a, 111b is assembled to the wall 107a, 107b of the engine casing 101.
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
It will be appreciated by those skilled in the art that although the disclosure has been described by way of example with reference to one or more examples, it is not limited to the disclosed examples and that alternative examples could be constructed without departing from the scope of the disclosure as defined by the appended claims.
Number | Date | Country | Kind |
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1520897.8 | Nov 2015 | GB | national |