Patent Description:
With the continuous development of automotive industry, the gearbox and the entire power system have to face more complicated operating conditions and higher requirements. To reduce the axial size, the integrated shaft structure supported by multiple bearings is necessary. In the conventional gearbox assembly or power assembly having a multi-bearing integrated shaft structure, the housings are positioned via positioning pins having a single diameter. When the housing assembly provided with the outer ring and rollers of the bearings is assembled onto the housing and shaft assembly provided with the inner ring of the bearings and positioning pins, there is not enough offset room between positioning pins and pin holes, so that the rollers and the inner ring of the bearings compress each other during the assembly process, and thus surface scratches are formed, which affect the performance and lifespan of the bearing and the entire system.

Document WO <CIT>, according to its abstract, discloses a shaft, wherein the shaft end part of the rotating shaft is supported by bearings installed in a casing, and the rotating shaft is fixed to the inner rings of the bearings by a shaft fixing means. The shaft end face of the rotating shaft is disposed in a position moved to the inside by a specified amount from the outer side surface of the inner ring of the bearing, the bolts are screwed into the screw parts of the rotating shaft. The outer peripheral side face presses the outer side face of the inner ring of the bearing on the outer peripheral side face of the retaining plate formed, so as to be allowed to come into contact with the outer side face of the inner ring of the bearing. By this pressing, the rotating shaft is fixed to the inner ring of the bearing with the spring action of the retaining plate.

With respect to the above problems, the present invention discloses a box assembly and the installation method thereof to overcome or at least partially solve the above problems.

In order to achieve the above object, the present invention adopts the following technical solutions.

An aspect of the present invention discloses an electrically driven power transmission system box assembly positioned by stepped pins as described by the independent claim <NUM>.

Optionally, the gap between the guide section of each stepped pin and the positioning pin hole of the first housing is further configured that, after more than half of the axial length of the rollers of the first bearing entered the raceway of the inner ring of the first bearing, the engagement section of each stepped pin begins to enter the positioning pin hole of the first housing; as the engagement section of each stepped pin enters the positioning pin hole of the first housing and is installed in place, a remaining part of the rollers of the first bearing fully enters the raceway of the inner ring of the first bearing.

Optionally, the diameter of the guide section of each stepped pin is determined based on a radial clearance of the first bearing, a position accuracy of a first bearing seat on the first housing, and a position accuracy of the positioning pin hole of the first housing.

Optionally, the lengths of the guide section and the engagement section of each stepped pin outside the housing are determined based on axial sizes of the housing, the first housing, and the shaft.

Optionally, the second bearing is disposed at a front end of the shaft, the middle bearing is disposed on a side of the middle housing that is close to the rear end of the shaft, and the second housing and the middle housing are fixed by positioning pins.

Another aspect of the present invention discloses a method for installing the box assembly as stated in any of the above items. The method comprises:.

The advantages and beneficial effects of the present invention are as follows.

The electrically driven box assembly positioned by stepped pins of the present invention utilizes the larger radial gap between the guide section of the stepped pin and the positioning pin hole of the first housing to prevent surface scratches on the raceway of the first bearing caused by the compression between the inner ring and rollers of the first bearing during the assembly process of the shaft and the first housing, thereby improving the service life of the bearing and the entire system.

By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to a person of ordinary skill in the art. The accompanying drawings are only used for the purpose of illustrating the preferred embodiments, and should not be considered as a limitation to the present invention. Moreover, throughout the drawings, the same reference numerals are used to denote the same components. In the drawings:.

where the stepped pin begins to enter the engagement section.

In the drawings: <NUM>. second housing; <NUM>. middle housing; <NUM>. first housing; <NUM>. housing and shaft assembly; <NUM>. stepped pin; <NUM>. outer ring of first bearing (rear bearing); <NUM>. roller of first bearing (rear bearing); <NUM>. inner ring of first bearing (rear bearing); <NUM>. shaft; <NUM>. second bearing; <NUM>. middle bearing.

In order to make the object, technical solutions, and advantages of the present invention clearer, the present invention will be described clearly and completely in conjunction with the specific embodiments and corresponding drawings. Obviously, the embodiments described are only part of rather than all of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without paying creative work shall fall within the protection scope of the present invention.

It should be understood that the terms "comprise/include", "consist of" or any other variants are intended to cover non-exclusive inclusion, so that the product, apparatus, process or method including a series of elements may not only include those elements, but may also include other elements not stated explicitly, or elements inherent to the product, apparatus, process or method. Without more limitations, an element defined by the phrase "comprise/include" or "consist of" does not exclude the case that there are other same elements in the product, apparatus, process or method including the element.

It should also be understood that, orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc. are orientation or positional relationship based on the drawings, which are merely for convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device, component or structure referred to must have a specific orientation, or must be constructed and operated with a specific orientation, they should not be construed as limiting the present invention.

In this embodiment, the right represents the front part, and the left represents the rear part.

In the present invention, unless otherwise expressly specified and defined, the terms "installed", "connected", "fixed" and the like should be understood in a broad sense, for example, it may be fixedly connected, or removably connected, or integrally connected; it may also be mechanically connected or electrically connected; it may also be directly connected or indirectly connected through a middleware; it may also be internally communicated or interacted between two components. For a person of ordinary skill in the art, the specific meaning of these terms in the present invention should be understood according to specific situations.

The technical solutions provided by the embodiments of the present invention are described in detail in conjunction with the accompanying drawings.

Refer to <FIG> and <FIG>, a specific embodiment of the present invention discloses an electrically driven power transmission system box assembly positioned by stepped pins. The electrically driven power transmission system comprises a power source, transmission components, vehicle control components, etc..

The box assembly specifically comprises: a housing and shaft assembly <NUM>, several stepped pins <NUM>, a first housing <NUM>, and a first bearing <NUM>-<NUM>. The housing and shaft assembly <NUM> comprises a housing and a shaft <NUM> supported on the housing. Each stepped pin <NUM> comprises an engagement section and a guide section. The diameter of the engagement section is larger than the diameter of the guide section. The engagement section is used to achieve the fixation between the housings. The engagement section and the housing are preferably in an interference fit. In order to achieve connection and fixation, at least a part of the engagement section must be connected to both the first housing and the housing of the housing and shaft assembly. As shown in <FIG> and <FIG>, the end part of the engagement section is fixed in the fixing pin hole of the housing.

The guide section is provided to facilitate the fixation of the first housing <NUM> onto the housing and shaft assembly and prevent scratching the first bearing during installation. Since the diameter of the guide section is less than the diameter of the engagement section, when the first housing <NUM> is installed and fixed to the housing and shaft assembly under the guidance of the guide section, there is a sufficient radial gap left between the inner ring of the first bearing, the rollers of the first bearing, and the outer ring of the first bearing to avoid scratches. After the above installation is completed, the rear end of the shaft can be supported on the first housing via the first bearing.

Preferably, the gap between the guide section of each stepped pin <NUM> and a positioning pin hole of the first housing <NUM> is configured to ensure, during an assembly process of more than half of an axial length of the rollers <NUM> of the first bearing entering a raceway of the inner ring <NUM> of the first bearing, a sufficient radial space between the inner ring <NUM> of the first bearing and an outer ring <NUM> of the first bearing and the rollers <NUM> of the first bearing, to prevent surface scratches on the rollers <NUM> of the first bearing and the inner ring <NUM> of the first bearing caused by over-positioning.

Furthermore, the gap between the guide section of each stepped pin <NUM> and the positioning pin hole of the first housing <NUM> is further configured that, after more than half of the axial length of the rollers <NUM> of the first bearing entered the raceway of the inner ring <NUM> of the first bearing, the engagement section of each stepped pin <NUM> begins to enter the positioning pin hole of the first housing <NUM>; as the engagement section of each stepped pin <NUM> enters the positioning pin hole of the first housing <NUM> and is installed in place, the remaining part of the rollers <NUM> of the first bearing fully enters the raceway of the inner ring <NUM> of the first bearing.

Preferably, the diameter of the guide section of each stepped pin <NUM> is less than the diameter of the positioning pin hole of the first housing <NUM>. The diameter of the guide section is determined based on a radial clearance of the first bearing, a position accuracy of a first bearing seat on the first housing <NUM>, and a position accuracy of the positioning pin hole of the first housing <NUM>.

Preferably, the lengths of the guide section and the engagement section of each stepped pin <NUM> outside the housing, the proportional relationship between the lengths, etc., are determined based on the size of the housing (especially the first housing) and the size of the shaft.

Furthermore , in an embodiment not part of the present invention, the first bearing is a split cylindrical roller bearing, the outer ring of the split cylindrical roller bearing is installed on the bearing seat of the first housing <NUM>, and the inner ring <NUM> of the first bearing of the split cylindrical roller bearing and the rollers <NUM> of the first bearing of the split cylindrical roller bearing are fixed at a rear end of the shaft <NUM>.

Specifically, the housing and shaft assembly <NUM> comprises a middle housing <NUM> and a second housing <NUM>, and the shaft <NUM> is fixedly supported on the middle housing <NUM> and the second housing <NUM> via the middle bearing <NUM> and the second bearing <NUM>, respectively.

Moreover, the second bearing <NUM> is disposed at a front end of the shaft <NUM>, the middle bearing <NUM> is disposed on a side of the middle housing <NUM> that is close to a rear end of the shaft <NUM>, and the second housing <NUM> and the middle housing <NUM> are fixed via positioning pins.

Optionally, the step <NUM> specifically comprises:.

It will be further explained below in conjunction with two specific embodiments.

The first embodiment discloses an electrically driven gearbox assembly positioned by stepped pins. As shown in <FIG>, it comprises: stepped pins <NUM> having a guide section and an engagement section and installed on a bonding surface of the housing; a (front) middle housing <NUM> and a first housing (rear housing) <NUM> positioned by using stepped pins, and a second housing (front housing) <NUM> connected to the middle housing; a second bearing (front bearing) <NUM>, a middle bearing <NUM> and a first bearing (rear bearing) that are respectively installed at bearing seats of the three housings; and a shaft <NUM> supported by the three bearings.

In this embodiment, there is no specific limitation on the selection of the rear bearing. The outer ring <NUM> and rollers <NUM> of the rear bearing are installed at the bearing seat of the rear housing <NUM>, and the inner ring <NUM> of the rear bearing is fixed on the outer circumference of the shaft <NUM>.

In this embodiment, as shown in <FIG>, the shaft <NUM> is first assembled into the front housing <NUM> and the middle housing <NUM> to obtain a housing and shaft assembly <NUM> on which the inner ring <NUM> of the rear bearing and two positioning stepped pins <NUM> are installed; then, the rear housing assembly on which the outer ring <NUM> and rollers <NUM> of the rear bearing are installed is assemble onto the housing and shaft assembly <NUM>. As the guide section of each stepped pin <NUM> installed in the housing and shaft assembly <NUM> enters the positioning pin hole at the bonding surface of the rear housing, the outer ring <NUM> and rollers <NUM> of the rear bearing gradually enter the raceway of the inner ring <NUM> of the rear bearing, thus completing the assembly.

In this embodiment, there is a larger radial gap between the guide section of each stepped pin <NUM> and the positioning pin hole at the bonding surface of the rear housing <NUM> to ensure, during the assembly process of more than half of the axial length of the rollers <NUM> of the rear bearing entering the raceway of the inner ring <NUM> of the rear bearing, a sufficient radial space between the inner ring <NUM> of the rear bearing and the outer ring <NUM> and rollers <NUM> of the rear bearing, to prevent surface scratches on the rollers <NUM> and the inner ring <NUM> of the rear bearing caused by over-positioning. As shown in <FIG>, after more than half of the axial length of rollers <NUM> of the rear bearing enter the raceway of the inner ring <NUM> of the rear bearing, the engagement section of each stepped pin <NUM> begins to enter the positioning pin hole of the rear housing; As shown in <FIG>, as the engagement section of each stepped pin <NUM> enters the positioning pin hole of the rear housing and is installed in place, the remaining part of the rollers <NUM> of the rear bearing fully enters the raceway of the inner ring <NUM> of the rear bearing.

In this embodiment, during the assembly process of the rollers <NUM> of the rear bearing entering the raceway of the inner ring <NUM> of the rear bearing, in order to ensure that the engagement section of each stepped pin <NUM> will not enter the positioning pin hole until more than half of the axial length of the rollers <NUM> of the rear bearing enters the raceway of the inner ring <NUM> of the rear bearing, the axial length of the transition section of each stepped pin <NUM> needs to be determined based on the sizes of relevant components and the axial size of the entire structure.

In this embodiment, during the assembly process of more than half of the axial length of the rollers <NUM> of the rear bearing entering the raceway of the inner ring <NUM> of the rear bearing, in order to ensure a sufficient radial space between the rollers <NUM> and the inner ring <NUM> of the rear bearing to prevent surface scratches on the raceway of the bearing, the outer diameter size and tolerance of the guide section of each stepped pin <NUM> needs to be determined based on the radial clearance of the rear bearing, the position accuracy of the rear bearing seat, the position accuracy of the positioning pin hole, etc..

The first embodiment utilizes the larger radial gap between the guide section of the stepped pin and the positioning pin hole to prevent surface scratches on the raceway of the rear bearing caused by the compression of the inner ring and rollers of the rear bearing during the assembly process of the shaft and the housing supported by the three bearings, thereby improving the service life of the bearing and the entire system.

Further embodiment not part of the present invention.

The further embodiment not part of the present invention discloses an electrically driven power transmission system positioned by stepped pins. As shown in <FIG>, it comprises: stepped pins <NUM> having a guide section and an engagement section and installed on the bonding surface of the housing; a middle housing <NUM> and a rear housing <NUM> positioned by using stepped pins; a front housing <NUM> connected to the middle housing; a front bearing <NUM>, a middle bearing <NUM> and a rear bearing that are respectively installed at bearing seats of the three housings; and a shaft <NUM> supported by the three bearings.

The embodiment differs from the first embodiment in that, as shown in <FIG>, the rear bearing in this embodiment is a split cylindrical roller bearing. The outer ring <NUM> of the rear bearing is installed at the bearing seat of the rear housing <NUM>, and the inner ring <NUM> and rollers <NUM> of the rear bearing are fixed on the outer circumference of the shaft <NUM>.

In this embodiment, the shaft <NUM> is first assembled into the front housing <NUM> and the middle housing <NUM> to obtain a housing and shaft assembly <NUM> on which the inner ring <NUM> and rollers <NUM> of the rear bearing and two positioning stepped pins <NUM> are installed; then, the rear housing assembly on which the outer ring <NUM> of the rear bearing is installed is assemble onto the housing and shaft assembly <NUM>. As the guide section of each stepped pin <NUM> installed in the housing and shaft assembly <NUM> enters the positioning pin hole at the bonding surface of the rear housing, the inner ring <NUM> and rollers <NUM> of the rear bearing gradually enter the raceway of the outer ring <NUM> of the rear bearing, thus completing the assembly. <FIG> shows the state that more than half of the axial length of the rollers <NUM> of the rear bearing enters the raceway of the outer ring <NUM> of the rear bearing, and at the same time each stepped pin <NUM> begins to enter the engagement stage.

This embodiment utilizes the larger radial gap between the guide section of each stepped pin and the positioning pin hole to prevent surface scratches on the raceway of the bearing caused by the compression of the inner surface of the outer ring and rollers of the bearing during the assembly process of the shaft and the housing supported by the three bearings, thereby improving the service life of the bearing and the entire system.

Claim 1:
An electrically driven power transmission system box assembly positioned by stepped pins (<NUM>), wherein:
the box assembly comprises: a housing and shaft assembly (<NUM>), several stepped pins (<NUM>), a first housing (<NUM>), and a first bearing (<NUM>-<NUM>);
the housing and shaft assembly (<NUM>) comprises a housing and a shaft (<NUM>) supported on the housing;
each stepped pin (<NUM>) comprises an engagement section and a guide section, a diameter of the engagement section is greater than a diameter of the guide section, and an end part of the engagement section is fixed in a fixing pin hole of the housing;
the first housing (<NUM>) is installed and fixed to the housing and shaft assembly (<NUM>) under guidance of the guide section; and
a rear end of the shaft (<NUM>) is supported on the first housing (<NUM>) via the first bearing (<NUM>-<NUM>); the housing of the housing and shaft assembly (<NUM>) comprises a middle housing (<NUM>) and a second housing (<NUM>), and the shaft (<NUM>) is fixedly supported on the middle housing (<NUM>) and the second housing (<NUM>) via a middle bearing (<NUM>) and a second bearing (<NUM>), respectively;
a gap between the guide section of each stepped pin (<NUM>) and a positioning pin hole of the first housing (<NUM>) is configured to ensure, during an assembly process of more than half of an axial length of rollers (<NUM>) of the first bearing (<NUM>-<NUM>) entering a raceway of an inner ring (<NUM>) of the first bearing (<NUM>-<NUM>) a radial space between the inner ring (<NUM>) of the first bearing (<NUM>-<NUM>) and, an outer ring (<NUM>) of the first bearing (<NUM>-<NUM>) and the rollers (<NUM>) of the first bearing, to prevent surface scratches on the rollers of the first bearing (<NUM>) and the inner ring of the first bearing (<NUM>) caused by over-positioning.