In-wheel motor drive device

A large gear and a small gear are provided to an intermediate shaft of an in-wheel motor drive device, and a final output gear configured to mesh with the small gear of the intermediate shaft is provided to an output shaft. The output shaft is supported by bearings on in-board and out-board sides, respectively, and the large gear of the intermediate shaft is arranged between the bearing configured to support the output shaft on the in-board side and the final output gear of the output shaft. The bearing and the large gear are arranged so that, when viewed from the axial direction, a tooth top circle of the large gear of the intermediate shaft and a radially outer circle of the bearing configured to support the output shaft on the in-board side have an intersection point.

TECHNICAL FIELD

The present invention relates to an in-wheel motor drive device, in which, for example, an electric motor and a wheel bearing are connected to each other via a speed reducer.

BACKGROUND ART

As an in-wheel motor drive device is mounted inside a wheel, and hence increase in weight of the drive device causes increase in unsprung load of a vehicle. The increase in unsprung load causes degradation in traveling stability and NVH characteristics. Consequently, downsizing and lightweighting of the drive device are important. Output torque of an electric motor is proportional to a size and a weight of the motor. Thus, in order to generate torque which is required for drive of the vehicle solely by the motor, a motor having a large size is required. Therefore, in the in-wheel motor drive device, rotation of the electric motor is transmitted to the wheel via a speed reduction mechanism, to thereby achieve the downsizing of the motor.

Incidentally, as disclosed in, for example, Patent Literature 1 (Japanese Patent Application Laid-open No. 2015-214273), an in-wheel motor drive device arranged in a wheel of a vehicle is connected to a suspension device such as a lower arm. For that reason, it is required that an installation space for the suspension device, in addition to the installation space for the in-wheel motor drive device, be secured in the wheel of the vehicle. Moreover, although not shown in the drawings, a brake caliper is also arranged in the wheel, and hence it is also required that an installation space for the brake caliper be secured. Thus, it is desired that a radial dimension of the in-wheel motor drive device be set as small as possible.

Even when the dimension in the radial direction is reduced while sacrificing a dimension in an axial direction (vehicle width direction) to meet such demands, an increase in axial dimension causes increase in protruding amount of the in-wheel motor drive device from the wheel toward an in-board side. As a result, there is a fear in that a vehicle body and the in-wheel motor drive device interfere with each other at the time of steering or vertical movement of the vehicle.

As one example of a structure having reduced in dimensions of the in-wheel motor drive device in the axial direction and the radial direction, for example, in Patent Literature 2 (Japanese Patent Application Laid-open No. 2012-214202), there is disclosed a method of arranging a speed reducer coaxially with a wheel center and arranging the speed reducer and a motor on the same section in the radial direction.

CITATION LIST

SUMMARY OF INVENTION

Technical Problem

In Patent Literature 2, output of a motor is transmitted to a speed reducer (planetary gear), which is arranged on a radially outer side of the motor, via an idler gear. Therefore, even when the in-wheel motor drive device can be downsized, the number of components increases by the number corresponding to the idler gear. As a result, it is conceivable that the NVH characteristics are degraded. As described above, when the downsizing of the in-wheel motor drive device is to be considered, another new problem generally arises as a trade-off. Thus, sufficient studies are required so as to minimize the influence of the new problem.

Based on the verification described above, the present invention has an object to reduce a dimension of an in-wheel motor drive device in the radial direction.

Solution to Problem

According to one embodiment of the present invention, which has been devised to achieve the above-mentioned object, there is provided an in-wheel motor drive device, comprising: an electric motor section; a wheel bearing section; and a speed reducer section, which is formed of a parallel shaft gear mechanism comprising an input shaft, an intermediate shaft, and an output shaft, and is configured to transmit output torque of the electric motor section, which is input to the input shaft, to the wheel bearing section via the intermediate shaft and the output shaft, the intermediate shaft comprising a large gear and a small gear, the output shaft comprising a final output gear configured to mesh with the small gear of the intermediate shaft, the output shaft being supported on its in-board side and out-board side by bearings, respectively, wherein the large gear of the intermediate shaft is arranged between the bearing configured to support the output shaft on the in-board side and the final output gear of the output shaft, and wherein, when viewed from the axial direction, a tooth top circle of the large gear of the intermediate shaft and a radially outer circle of the bearing configured to support the output shaft on the in-board side have an intersection point.

With the configuration described above, the large gear of the intermediate shaft can be increased in radial dimension. Thus, the gears can be efficiently accommodated in a space inside a case while securing a required speed reduction ratio. As a result, the in-wheel motor drive device can be reduced in radial dimension. Through employment of the configuration described above, there is a case in which assembly workability of the in-wheel motor drive device is degraded. However, such a problem can easily be eliminated by countermeasures such as contriving a jig. Besides, such a problem does not adversely affect a function or a performance of the in-wheel motor drive device.

In addition, the in-wheel motor drive device is desired to be configured such that the intermediate shaft is supported on its in-board side and out-board side by bearings, respectively, the final output gear is arranged between the bearing configured to support the intermediate shaft on the out-board side and the large gear of the intermediate shaft, and that, when viewed from the axial direction, the tooth top circle of the final output gear of the output shaft and the radially outer circle of the bearing configured to support the intermediate shaft on the out-board side have an intersection point. With this, the final output gear can be increased in radial dimension, thereby being capable of obtaining an effect similar to the effect described above.

Advantageous Effects of Invention

According to the present invention, the in-wheel motor drive device can be reduced in dimension in the radial direction. As a result, a sufficient accommodation space for the suspension arm and the brake caliper can be secured in the wheel. Thus, when the in-wheel motor drive device is to be mounted to, for example, electric vehicles there can be used existing suspension devices and braking devices, thereby being capable of reducing development costs.

DESCRIPTION OF EMBODIMENTS

An in-wheel motor drive device according to one embodiment of the present invention is described in detail with reference to the drawings.

FIG. 6is a schematic plan view of an electric vehicle11on which in-wheel motor drive devices21are mounted, and FIG.7is a schematic sectional view of the electric vehicle11, when viewed from a rear side.

As illustrated inFIG. 6, an electric vehicle11comprises a chassis12, front wheels13serving as steered wheels, rear wheels14serving as driving wheels, and in-wheel motor drive devices21configured to transmit driving force to the rear wheels14. As illustrated inFIG. 7, each of the rear wheel14is accommodated inside a wheel housing15of the chassis12and fixed below the chassis12via a suspension device (suspension)16.

In the suspension device16, horizontally extending suspension arms are configured to support the rear wheels14, and a strut comprising a coil spring and a shock absorber is configured to absorb vibrations that each of the rear wheel14receives from the ground to suppress the vibrations of the chassis12. In addition, a stabilizer configured to suppress tilting of a vehicle body during turning and other operations is provided at the connecting portions of the right and left suspension arms. In order to improve a followability of following irregularities of a road surface to transmit the driving force of the rear wheels14to the road surface efficiently, the suspension device16is an independent suspension type capable of independently moving the right and left wheels up and down.

The electric vehicle11does not need to comprise a motor, a drive shaft, a differential gear mechanism, and other components on the chassis12because the in-wheel motor drive devices21configured to drive the right and left rear wheels14, respectively, are arranged inside the wheel housings15. Accordingly, the electric vehicle11has advantages in that a large passenger compartment space can be provided and that rotation of the right and left rear wheels14can be controlled, respectively.

Prior to discuss a characteristic configuration of this embodiment, an overall configuration of the in-wheel motor drive device21is described with reference toFIG. 1toFIG. 3. In the following description, under a state in which the in-wheel motor drive device21is mounted to the vehicle, a side closer to an outer side of the vehicle in a vehicle width direction is referred to as “out-board side”, and a side closer to a center of the vehicle body is referred to as “in-board side”.

FIG. 1is a longitudinal sectional view of the in-wheel motor drive device taken along the line P-P ofFIG. 2, when viewed from the direction indicated by the arrows.FIG. 2is a transverse sectional view of the in-wheel motor drive device taken along the line Q-Q ofFIG. 1, when viewed from the direction indicated by the arrows.FIG. 3is a transverse sectional view taken along the line R-R ofFIG. 1, when viewed from the direction indicated by the arrows.

As illustrated inFIG. 1, the in-wheel motor drive device21comprises a motor section A configured to generate driving force, the speed reducer section B configured to reduce a speed of rotation of the motor section A to output the rotation, and a wheel bearing section C configured to transmit the output from the speed reducer section B to the rear wheels14serving as driving wheels. The electric motor section A, the speed reducer section B, and the wheel bearing section C are each accommodated in a casing22. The casing22has a dividable structure (seeFIG. 5) in consideration of workability at the time of assembling the electric motor section A, the speed reducer section B, or the wheel bearing section C.

The electric motor section A is an electric motor26of a radial gap type, comprising a stator23fixed to the casing22, a rotor24arranged on a radially inner side of the stator23at an opposed position with a gap, and a motor rotation shaft25, which is arranged on a radially inner side of the rotor24so as to rotate integrally with the rotor24. The motor rotation shaft25is rotatable at high speed about ten and several thousand rotations per minute. The stator23is formed by winding a coil around a magnetic core, and the rotor24is formed of permanent magnets, etc.

The motor rotation shaft25is supported at its end portion on one side in the axial direction (left side inFIG. 1) by a rolling bearing40, and is supported at its end portion on another side in the axial direction (right side inFIG. 1) by a rolling bearing41so as to be freely rotatable with respect to the casing22.

The speed reducer section B comprises an input gear30, an input-side intermediate gear31(large gear) and an output-side intermediate gear32(small gear), which are intermediate gears, and a final output gear35. The input gear30is formed integrally with an input shaft30a, and the input shaft30ais coaxially connected to the motor rotation shaft25by spline fitting (including serration fitting, and the same holds true in the following description). An intermediate shaft S1comprising the input-side intermediate gear31and the output-side intermediate gear32is formed integrally with the intermediate gears31and32. An output shaft36comprising the final output gear35is formed integrally with the final output gear35. Any one or two of more among the gears30,31,32, and35may be formed separately from corresponding one of the shafts so as to be connected to the corresponding one of the shafts by, for example, spline fitting.

The input shaft30a, the intermediate shaft S1, and the output shaft36are arranged in parallel with one another. The rolling bearings42and43are arranged on both sides of the input gear30of the input shaft30ain the axial direction, and the input shaft30ais supported by the rolling bearings42and43so as to be freely rotatable with respect to the casing22. Under a state in which the input-side intermediate gear31is arranged on the in-board side, and the output-side intermediate gear32is arranged on the out-board side, the intermediate shaft S1is supported by two rolling bearings44and45so as to be freely rotatable with respect to the casing22. Moreover, rolling bearings48and49are arranged on both sides of the final output gear35of the output shaft36in the axial direction, and the output shaft36is supported by the rolling bearings48and49so as to be freely rotatable with respect to the casing22. As each of the rolling bearings40to45,48, and49described above, there is used a bearing capable of receiving both a radial load and a thrust load, for example, a deep-groove ball bearing.

With regard to the bearings44and45configured to support the intermediate shaft S1on the in-board side and the out-board side, the rolling bearing44provided on the input-side intermediate gear31side being the in-board side has a diameter larger than that of the rolling bearing45provided on another side. The rolling bearing44provided on the in-board side has an inner-diameter dimension larger than an outer-diameter dimension of the rolling bearing45on the out-board side. Moreover, with regard to the bearings48and49configured to support the output shaft36on the in-board side and the out-board side, the rolling bearing49provided on the final output gear35side being the out-board side has a diameter larger than that of the rolling bearing48provided on another side. The rolling bearing49provided on the out-board side has an inner-diameter dimension smaller than an outer-diameter dimension of the rolling bearing48provided on the in-board side. The rolling bearing49provided on the out-board side has an outer-diameter dimension larger than an outer-diameter dimension of an outer ring53, which is described later, of the wheel bearing section C.

As illustrated inFIG. 2andFIG. 3, a center O2of the intermediate shaft S1is arranged between a center O1of the input shaft30a(which is also a center of the motor rotation shaft25) of the speed reducer section B and a center O3of the wheel bearing section C. The centers O1, O2, and O3each are arranged so that lines connecting the centers O1, O2, and O3forma triangle, thereby achieving downsizing of an outer contour of the in-wheel motor drive device21. With this, the in-wheel motor drive device21can be mounted in a rear wheel70of an existing internal combustion engine. An outer-diameter dimension (indicated by the one-dot chain line inFIG. 3) of the electric motor section A is set so that, when viewed from the axial direction, the electric motor section A is superimposed with the rolling bearing48configured to support the output shaft36on the out-board side.

FIG. 2is a transverse sectional view taken along the line Q-Q ofFIG. 1, when viewed from the direction indicated by the arrows, that is, viewed from the out-board side. The rolling bearing49configured to support the output shaft36on the out-board side is arranged in a radially-inner-side recess portion47of the final output gear35. The rolling bearing49configured to support the output shaft36on the out-board side and the rolling bearing45configured to support the intermediate shaft S1on the out-board side are arranged so that respective bearing widths are prevented from being superimposed with each other in the axial direction. Moreover,FIG. 3is a transverse sectional view taken along the line R-R ofFIG. 1, when viewed from the direction indicted by the arrows, that is, viewed from the in-board side. The rolling bearing44configured to support the intermediate shaft S1on the in-board side is arranged in a radially-inner-side recess portion33of the input-side intermediate gear31.

As illustrated inFIG. 1, in the speed reducer section B, the input gear30and the input-side intermediate gear31mesh with each other, and the output-side intermediate gear32and the final output gear35mesh with each other. The number of teeth of the input-side intermediate gear31is larger than the number of teeth of each of the input gear30and the output-side intermediate gear32, and the number of teeth of the final output gear35is larger than the number of teeth of the output-side intermediate gear32. With the configuration described above, a parallel shaft gear speed reducer39configured to reduce a speed of the rotary motion of the motor rotation shaft25in two stages is thus configured.

In this embodiment, helical gears are used as the input gear30, the input-side intermediate gear31, the output-side intermediate gear32, and the final output gear35forming the parallel shaft gear speed reducer39. With the helical gears, the number of teeth which are simultaneously in mesh becomes larger, and teeth contact is dispersed. Therefore, the helical gears are effective in quietness and less torque fluctuation. In consideration of a meshing ratio and a limit rotation number of the gears, it is preferred that modules of the gears be set to from 1 to 3.

The wheel bearing section C is formed of a wheel bearing50of an inner-ring rotation type. The wheel bearing50is a double-row angular ball bearing mainly comprising an inner member61, the outer ring53, balls56, and a retainer (not shown). The inner member61comprises a hub ring60and an inner ring52. The hub ring60comprises a flange portion60afor mounting a wheel, which is formed on an outer periphery of the hub ring60on the out-board side. The inner ring52is fitted to a small-diameter step portion of the hub ring60on the in-board side. After that, an in-board-side end portion of the hub ring60is caulked. The caulked portion60bis configured to, after assembly of the wheel bearing50, position the inner ring52in the axial direction and apply a preload on the wheel bearing50. An inner raceway surface54on the out-board side is formed on an outer periphery of the hub ring60, and an inner raceway surface54on the in-board side is formed on an outer periphery of the inner ring52. Although not shown, a brake disc and a wheel are mounted to the flange portion60afor mounting a wheel.

Double-row outer raceway surfaces55are formed on an inner periphery of the outer ring53so as to correspond to the inner raceway surface54of the hub ring60and the inner raceway surface54of the inner ring52. A flange portion is formed on an outer periphery of the outer ring53. The flange portion is fastened and fixed to the casing22by a bolt71through intermediation of an attachment46. Moreover, the outer ring53is fastened and fixed by a bolt to a mounting portion72for mounting to the suspension device. The output shaft36is fitted to the inner periphery of the hub ring60by spline fitting so as to be connected to the hub ring60in a torque-transmittable manner.

In the in-wheel motor drive device21, for cooling of the electric motor26and for lubrication and cooling of the speed reducer39, lubricating oil is fed to relevant portions by a rotary pump (not shown). The inside of the wheel bearing50is lubricated by grease.

The in-wheel motor drive device21is accommodated inside the wheel housing15(seeFIG. 7), and thus becomes unsprung load. Therefore, downsizing and reduction in weight thereof are required. Thus, through combination of the parallel shaft gear speed reducer39having the above-mentioned configuration and the motor28, the small-sized motor26with low torque and high-speed rotation can be used. For example, in a case in which the parallel shaft gear speed reducer39having a speed reduction ratio of 11 is used, through employment of the electric motor26with high-speed rotation about ten and several thousand rotations per minute, the downsizing of the electric motor26can be achieved. With this downsizing, the compact in-wheel motor drive device21can be achieved. As a result, the unsprung weight is suppressed, thereby being capable of obtaining the electric vehicle11which is excellent in traveling stability and NVH characteristics.

The overall configuration of the in-wheel motor drive device21according to this embodiment is as described above. Characteristic configurations are described below.

As illustrated inFIG. 1, in the in-wheel motor drive device21according to this embodiment, the input-side gear31(large gear) of the intermediate shaft S1is arranged between the rolling bearing48, which is arranged on the in-board side of the output shaft36, and the final output gear35of the output shaft36. Moreover, when viewed from the axial direction, as illustrated inFIG. 3, a tooth top circle X1of the input-side intermediate gear31of the intermediate shaft S1and a radially outer circle (indicated by one-dot chain line) of the bearing48configured to support the output shaft36on the in-board side have two intersection points.

In addition, the final output gear35of the output shaft36is arranged between the rolling bearing45configured to support the intermediate shaft S1on the out-board side and the input-side intermediate gear (large gear)31of the intermediate shaft S1. When viewed from the axial direction, as illustrated inFIG. 2, a tooth top circle X2of the final output gear35and a radially outer circle Y2(indicated by one-dot chain line) of the bearing45configured to support the intermediate shaft S1on the out-board side have two intersection points.

As illustrated inFIG. 2, when viewed from the axial direction, the tooth top circle X1of the input-side intermediate gear31of the intermediate shaft S1and a radially outer circle Y3of the bearing49configured to support the output shaft36on the out-board side also have two intersection points. Moreover, as illustrated inFIG. 3, when viewed from the axial direction, the tooth top circle X2of the final output gear and a radially outer circle Y4of the bearing44configured to support the intermediate shaft S1on the in-board side also have two intersection points.

The “radially outer circles” of the bearings described above correspond to circles which are depicted when outer peripheral surfaces45aand48bof the outer rings being elements of the rolling bearings45and48are viewed from the axial direction.

Bearing sizes of the rolling bearings42to45,48, and49used for supporting the input shaft30a, the intermediate shaft S1, and the output shaft36are determined based on magnitudes of torque to be transmitted by the shafts30a, S1, and36and maximum loads (radial load and thrust load) which act on the bearings. Thus, outer-diameter dimensions of the rolling bearings42to45,48, and49are also determined based on torque and loads in a similar manner. Therefore, as illustrated inFIG. 3, when the tooth top circle X1of the input-side intermediate gear31and the radially outer circle Y1of the bearing48configured to support the output shaft36on the in-board side are brought into a state of intersecting each other when viewed from the axial direction, a radial dimension of the entirety of the in-wheel motor drive device21can be reduced while securing a speed reduction ratio required for the speed reducer39.

For description of the effect described above, as a comparative example, assumption is made of a configuration in which, as illustrated inFIG. 4, the tooth top circle of the input-side intermediate gear31of the intermediate shaft S1and the radially outer circle of the bearing48configured to support the output shaft36on the in-board side have no intersection point. In this case, a radial dimension of the input-side intermediate gear31being the large gear is reduced. Thus, when positions of the centers O1, O2, and O3of the shafts are not changed, it is required that the radial dimension of the input gear30of the input shaft30abe increased for meshing. As a result, a speed reduction ratio required for the entirety of the speed reducer39cannot be obtained. In order to obtain an appropriate speed reduction ratio, it is required that respective inter-axis distances (between O1and O2and between O2and O3) be increased. As a result, a radial dimension of the in-wheel motor drive device21increases. Such tendency is more conspicuous in the configuration in which, as illustrated inFIG. 4, the tooth top circle of the final output gear35and the radially outer surface of the bearing45configured to support the intermediate shaft S1on the out-board side do not have the intersection point.

In contrast, with the configuration ofFIG. 1, a radial dimension of the input-side intermediate gear31increases. Thus, each of the gears can be efficiently accommodated in the space inside the case22while securing the required speed reduction ratio. Thus, the radial dimension of the in-wheel motor drive device21can be reduced. With this, a sufficient accommodation space for the suspension arms and the brake caliper can be secured in the wheel70. Accordingly, when the in-wheel motor drive device21is to be mounted to the electric vehicle11, existing suspension devices or existing braking devices can be used, thereby being capable of reducing the development costs. In the description above, illustration is given of the case in which the two circles intersect at the two intersection points. However, the number of the intersection point of the two circles may be one (state in which two circles are in tangent with each other).

At the time of assembly of the parallel shaft speed reducer39described above, the input shaft30a, the intermediate shaft S1, and the output shaft36are incorporated into the casing22under a state in which, for prevention of creep, the rolling bearings42to45,48, and49are press-fitted in advance to respective outer peripheral surfaces of the shafts on the rotation side (seeFIG. 5). As in the comparative example illustrated inFIG. 4, when there is given a configuration in which, when viewed from the axial direction, the tooth top circle of the input-side intermediate gear31and the radially outer circle of the bearing48do not have the intersection points and the tooth top circle of the final output gear35and the radially outer surface of the bearing45do not have the intersection points, the shafts30a, S1, and36each integrally comprising the gear can be sequentially incorporated into the casing22in the order of the input shaft30a, the intermediate shaft S1, and the output shaft36. In contrast, with the configuration illustrated inFIG. 1, after the input shaft30aand the intermediate shaft S1are incorporated into the casing22, the bearing45and the final output gear35interfere with each other, and the bearing48and the input-side intermediate gear31interfere with each other, with the result that the output shaft36cannot be incorporated into the casing22.

In consideration of this point, assembly in the case in which the parallel shaft speed reducer39having the configuration illustrated inFIG. 1is adopted can be performed by holding the input shaft30a, the intermediate shaft S1, and the output shaft36of the parallel shaft speed reducer39in a state of an assembly with respective gears in mesh with each other and simultaneously incorporating the assembly into the casing22. At the time of mass production of the in-wheel motor drive device21, the parallel shaft speed reducer39can be assembled to the casing22without any particular inconvenience through use of a jig for holding the three shafts30a, S1, and36in the state of the assembly.

In a general parallel shaft speed reducer, in consideration of workability at the time of assembly described above, it is a common practice to adopt a configuration in which, as in the comparative example illustrated inFIG. 4, when viewed from the axial direction, the tooth top circle of the input-side intermediate gear31and the radially outer circle of the bearing48do not have the intersection point and the tooth top circle of the final output gear35and the radially outer surface of the bearing45do not have the intersection point. The present invention gives focus on the fact that, even when the assembly workability is somewhat sacrificed, such disadvantage can easily be eliminated. The configuration described above is adopted to achieve reduction in radial dimension of the in-wheel motor drive device21. For achievement of downsizing of the in-wheel motor drive device21, assembly workability is considered as a matter subjected to a trade-off. In this regard, the present invention involves a novel idea different from existing means for downsizing.

In the description of the embodiment above, there is exemplified the electric motor26of a radial gap type as the motor section A. However, a motor having any other configuration may be adopted. For example, there may be adopted an electric motor of an axial gap type, comprising a stator fixed to a casing and a rotor arranged so as to be opposed with a gap to the stator on an inner side in the axial direction. Moreover, there is exemplified the case in which the parallel shaft speed reducer39with two-stage speed reduction is used. However, the present invention is not limited to be applied to such configuration, and may be similarly applied to a speed reducer configured to perform speed reduction with three or more stages.

Further, in the description described above, there is given a case in which electric power is supplied to the motor section A to drive the motor section and the power from the motor section A is transmitted to the rear wheels14. Conversely to this, however, when a vehicle decelerates or descends a slope, the power from the rear wheel14side may be converted at the speed reducer section B into high-rotation low-torque rotation so that the rotation is transmitted to the motor section A for electric power generation in the motor section A. Further, the electric power generated in the motor section A may be stored in a battery so that the electric power is used to drive the motor section A later or to operate other electric devices equipped in the vehicle.

Moreover, in the embodiment described above, as illustrated inFIG. 6andFIG. 7, there is exemplified the electric vehicle11comprising the rear wheels14as driving wheels. However, the electric vehicle11may comprise the front wheels13as driving wheels, or may be a four-wheel drive vehicle. In the “electric vehicle” herein encompasses all automobiles configured to obtain a driving force from the electric power, and thus may include, for example, a hybrid car.

The present invention is not limited to the above-mentioned embodiment. As a matter of course, the present invention may be carried out in various modes without departing from the gist of the present invention. The scope of the present invention is defined in the scope of claims, and encompasses equivalents described in claims and all changes within the scope of claims.

REFERENCE SIGNS LIST