阅读说明：本技术 用于机动车的测功机测试的方法和装置 (Method and device for dynamometer testing of motor vehicle ) 是由 克里斯蒂安·恩斯特伦 尼尔斯·G·恩斯特伦 强尼·费恩隆德 于 2019-01-31 设计创作，主要内容包括：本发明涉及一种配置为在车辆测功机系统中使用的测功机测试单元,其用于车辆的测功机测试,所述测功机测试单元被配置为连接至车辆的轮轴,所述测功机测试单元包括具有定子和转子的动力源并且被配置为在测试期间将转矩施加至被测试车辆的轮轴,所述动力源由定子支承承载,所述定子以轴颈关联于定子支承,所述测功机单元还包括用于测量转矩的装置,所述装置包括弹性带,其中所述弹性带将所述定子连接至所述定子支承,从而抑制所述定子与所述定子支承之间的相对旋转运动,并且所述弹性带被配置为传递所述定子与所述定子支承之间的力,所述弹性带在某种程度上被牢固地固定,使得其在所述弹性带的纵向方向上受到均匀的拉伸预应力。(The invention relates to a dynamometer test unit configured for use in a vehicle dynamometer system for dynamometer testing of a vehicle, the dynamometer test unit being configured for connection to an axle of the vehicle, the dynamometer test unit including a power source having a stator and a rotor and being configured to apply a torque to the axle of the vehicle under test during testing, the power source being carried by a stator bearing, the stator being journalled in a stator bearing, the dynamometer unit further including means for measuring the torque, the means including an elastic band, wherein the elastic band connects the stator to the stator bearing, thereby inhibiting relative rotational movement between the stator and the stator bearing, and the elastic band is configured to transmit forces between the stator and the stator bearing, the elastic band being fixed somewhat firmly, so that it is subjected to a uniform tensile prestress in the longitudinal direction of the elastic belt.)

1. A dynamometer test unit configured for use in a vehicle dynamometer system, for dynamometer testing of a vehicle, the dynamometer test unit configured to be connected to an axle of a vehicle, the dynamometer test unit including a power source having a stator and a rotor and configured to apply a torque to the axle of the vehicle under test during testing, the power source being carried by a stator support, the stator being journalled with the stator support, wherein the means for measuring the torque comprises, for example, an elongated elastic band, wherein the elastic band connects the stator to the stator support, thereby inhibiting relative rotational movement between the stator and the stator support, and the elastic band is configured to transmit forces between the stator and the stator support, the elastic band is fixed so firmly that it is subjected to a uniform tensile prestress in the longitudinal direction of the elastic band.

2. Dynamometer test unit according to claim 1, characterized in that the elastic band is tensile prestressed to some extent in its longitudinal direction, so that the elastic band is also tensile prestressed when being firmly fixed to the stator support but released from the stator, or the elastic band is also tensile prestressed when being firmly fixed to the stator but released from the stator support.

3. Dynamometer test unit according to claim 1 or 2, characterized in that e.g. both ends of the elongated elastic band are firmly fixed to the stator or stator support, wherein the part between the two ends of the elastic band is firmly fixed to the other of the stator or stator support, wherein the elastic band is firmly fixed such that the band is also pre-stressed in tension in the longitudinal direction when the part between the two ends is released from the other of the stator or stator support.

4. Dynamometer test unit according to any of claims 1-3, characterized in that the dynamometer test unit during testing is designed for absorbing at most a first predetermined torque, the tensile prestress to which the elastic band is subjected at least corresponds to the stress to which the elastic band is subjected when the dynamometer test unit absorbs the first predetermined torque.

5. Dynamometer test unit according to any of the claims 1-4, characterized in that both ends of the elastic band are firmly fixed to the stator support, wherein the central part of the elastic band is firmly fixed to the stator.

6. Dynamometer test unit according to any of the claims 1-5, characterized in that the belt is pre-stressed under a force acting in the longitudinal direction of the belt, which is achieved by the belt fixing one end to the stator or stator support and being subjected to the force during assembly while fixing the other end to the stator or stator support.

7. Dynamometer test unit according to any of the claims 1-6, characterized in that the torque measurement means further comprise at least one pair of strain gauges (R1/R4; R2/R3) fixed to e.g. the elongated belt, the strain being measured by measuring the relative resistance difference caused by the strain of the belt when the dynamometer test unit is subjected to a torque.

8. Dynamometer test unit according to any of claims 1-7, characterized in that the belt's end portions are firmly fixed to either of the stator and stator support and its central portion is firmly fixed to the other of the stator and stator support, and a first pair of strain gauges (R1/R4; R2/R3) is fixed to the belt on one side of the central belt portion and a second pair of strain gauges (R1/R4; R2/R3) is fixed to the belt on the other side of the central belt portion, the strain gauges being connected in an electronic measuring bridge circuit and measuring the force acting on the belt by measuring the relative resistance difference caused by the strain when torque is applied to the dynamometer test unit.

9. Dynamometer test unit according to claim 8, characterized in that a third pair of strain gauges is fixed to the belt on one side of the central belt portion comprising the first pair of strain gauges (R1/R4; R2/R3) and is arranged at an angle, e.g. perpendicular, with respect to the first pair of strain gauges (R1/R4; R2/R3), and

a fourth pair of strain gauges is fixed to the belt on one side of the central belt portion including the second pair of strain gauges (R1/R4; R2/R3) and is arranged at an angle, e.g. perpendicular, with respect to the second pair of strain gauges, the third and fourth pairs of strain gauges being connected in an electronic measuring bridge circuit and the force acting on the belt being measured by measuring the relative resistance difference caused by the strain of the belt when a torque is applied to the dynamometer measurement unit.

10. The dynamometer test unit of any one of claims 1-9, wherein the stator is supported by the stator bearing by a tubular stator element journalled for rotational movement relative to the stator bearing by a bearing assembly comprising at least two antifriction bearings, wherein the output shaft of the dynamometer test unit is journalled for rotation relative to the stator on antifriction bearings within and concentric with the tubular stator element.

11. The dynamometer test unit of claim 10, the bearing assembly being disposed at or towards an end of the stator support that is configured to be connected to an axle during testing, wherein a greater portion of the power source, when carried by the bearing assembly, extends in cantilever fashion from the bearing assembly to an opposite side of the stator support.

12. The dynamometer test unit of any of claims 1-11, the stator bearing including a ground engaging support that prevents rotation of the dynamometer test unit when subjected to torque.

13. Dynamometer test unit according to any of claims 1-12, characterized in that the dynamometer test unit (110, 111) is arranged to stand freely on a surface and be connected to the vehicle by means of a rigid coupling to the axle, while supporting the weight of the vehicle by the rigid coupling.

14. Vehicle dynamometer system for dynamometer testing of a vehicle, comprising at least one dynamometer cell according to any of claims 1-13.

15. The vehicle dynamometer system of claim 14, wherein measuring when torque:

-determining a first measured value of a first reaction torque of the first dynamometer power source,

-determining the effect of the moment of inertia on said first measured value of said first reaction torque, and

-compensating said first measured value of said first reaction torque by the influence of said determined moment of inertia.

16. The vehicle dynamometer system of claim 14 or 15, wherein:

-the vehicle dynamometer system being configured to determine a plurality of torque values for each revolution of the output shaft of the dynamometer test unit, and

-the vehicle dynamometer system comprising means for correlating the determined torque value with a rotation angle of an output shaft and/or axle of the corresponding dynamometer.

17. Vehicle dynamometer system according to any of the preceding claims, characterized in that:

-the vehicle dynamometer system being configured to measure torque experienced when the dynamometer test unit undergoes steering motion about a substantially vertical axis when attached to a vehicle under test.

18. Method of assembling a dynamometer test unit configured for use in a vehicle dynamometer system for dynamometer testing of a vehicle, the dynamometer test unit being configured for connection to an axle of a vehicle, the dynamometer test unit including a power source having a stator and a rotor and being configured to apply a torque to the axle of the vehicle under test during testing, the power source being carried by a stator support, the stator being journalled in the stator support, wherein means for measuring the torque include, for example, an elongated elastic band, wherein the elastic band connects the stator to the stator support, thereby limiting relative rotational movement between the stator and the stator support, and the elastic band is configured to transmit a force between the stator and the stator support, one end of the elastic band being fixedly secured to one of the stator and the stator support, wherein after attaching the first end, the second end is attached to the one of the stator or stator support when under tensile stress in the longitudinal direction such that the securely fixed elastic band is thereby under uniform tensile pre-stress in the longitudinal direction of the elastic band.

19. The assembly method of claim 18, the elastic band further comprising at least one pair of strain gauges (R1/R4; R2/R3) fixed to, for example, the elongate band, the strain being measured by measuring the relative resistance difference caused by the strain of the band when the dynamometer test unit is subjected to a torque, the assembly method further comprising:

by measuring the tensile stress when the strip is subjected to a force using the strain gauge, a predetermined tensile prestress is determined when the strip is firmly fixed.

Technical Field

The present invention relates to dynamometer testing of a vehicle, and more particularly to a dynamometer testing unit for use when a dynamometer tests a vehicle having at least one axle and a power source that applies power to the first axle. The invention also relates to an assembling method for assembling the dynamometer testing unit.

Background

Dynamometer testing of vehicles is known per se and may be performed, for example, by a drum-type (drum-simulated road surface) dynamometer equipped with large drums supporting wheels for applying braking torque to driving wheels of the vehicle. The rollers are typically of the friction type, wherein the dynamometer system engages the tires of the driven wheels by frictional engagement. The inevitable, and often unpredictable, slip and friction between the tyre and the friction roller may lead to undesirable errors in the test results.

Friction roller type systems may not always be able to provide the desired measurement accuracy and/or measurement freedom.

Another type of vehicle dynamometer system uses a device for vehicle dynamometer testing in which a load absorbing device (e.g., in the form of a hydrostatic pump assembly) has an input shaft for engagement with a drive shaft of the vehicle under test. Each drive shaft of the vehicle may be fixedly connected to such a separate device, so that the total effective torque from the vehicle may be accurately measured.

This type of system can be used for both two wheel drive systems and four wheel drive systems or more to perform complex tests. Further, a vehicle transmission may include various power sources as well as multiple power sources for providing power to the axles of a vehicle. These power sources may be arranged to provide both propulsion power as well as braking power, for example for regenerative braking. The increased complexity of vehicle transmissions has created a desire to be able to test other functions using dynamometer testing systems as well. In addition, vehicles are increasingly being equipped with driver assistance systems, wherein such systems can be utilized in various situations to assist the driver.

The increasing complexity of vehicle control systems may require testing under a large number of actual driving conditions and conditions to ensure the desired functionality. It would be desirable if at least a portion of such actual driving tests could be replaced with tests using a vehicle dynamometer.

Objects and most important features of the invention

An object of the present invention is to provide a vehicle dynamometer which has an accurate function of testing a vehicle even when a dominant condition changes with each test during a test.

According to the present invention there is provided a dynamometer test unit configured for use in a vehicle dynamometer system for dynamometer testing of a vehicle, the dynamometer test unit being configured for connection to an axle of a vehicle under test, the dynamometer test unit including a power source having a stator and a rotor and being configured to apply torque to the axle of the vehicle under test during testing, the power source being carried by a stator bearing, the stator being journalled with the stator bearing. The dynamometer cell includes a means for measuring torque, the means including an elastic band connecting the stator to the stator support, thereby inhibiting relative rotational movement between the stator and the stator support, and the elastic band is configured to transmit forces between the stator and the stator support, the elastic band being fixed in a manner so firmly that it is subjected to a uniform tensile prestress in the longitudinal direction of the elastic band.

The elastic band may be an elongated elastic band.

The dynamometer test unit may form a component of a vehicle dynamometer system that includes one or more dynamometer test units.

The stator support may include a ground engaging support configured to allow the dynamometer test unit to stand freely on a surface (e.g., the ground of a location where testing is performed).

The ground engaging supports may prevent the dynamometer test unit from rotating when subjected to torque, and thus, subject to the torque to which the dynamometer test unit is subjected.

Accurate measurements can be provided when testing a vehicle using a system in which one or more dynamometer test units, including a power source, are connected to the axles of the vehicle. For example, a vehicle may be tested during rapid acceleration and wheel torque may be measured in an accurate manner throughout the vehicle engine speed range. In general, the torque/load can be arranged to be measured directly on the measured shaft by means of a measuring device. However, such measurements face difficulties, e.g. with respect to rotating parts etc. Alternatively, as in the present invention, the torque load exerted on the rotating shaft may be measured by measuring the reaction load. The measurement of the reaction load/torque follows the following facts: for each action there is an equal and opposite reaction force. For dynamometer measurements this means that the load/torque can be measured in this case by measuring the amount of load/torque required to prevent rotation of the dynamometer test unit. This load is commonly referred to as a reaction load or reaction torque. This is also the torque measured according to the invention.

As mentioned, the stator is journalled to a stator support, so that the stator, and thus the power source comprising the stator housing, is rotatable relative to the stator support. The rotational movement is then limited by, for example, an elongated elastic band connecting the stator to the stator support. When torque is applied to the dynamometer test cell, the power source will not be able to rotate through the elastic band, which then transfers the torque experienced by the stator from the stator to the stator support, the band forming a tension transfer link between the stator and the stator support.

The elastic band forms part of a device for measuring the torque to which the dynamometer test unit is subjected, since the elastic band is also subjected to this torque.

The torque may be measured by measuring the tensile stress to which the elastic band is subjected.

To measure the tensile stress experienced by the elastic belt, the elastic belt is subjected to a tensile pre-stress. The stress-strain curve of a material typically has a proportional portion where the strain produced by the material is proportional to the force applied. The pre-stress may be controlled at a level on the stress-strain curve at the proportional part to ensure that the strain produced is proportional to the force applied.

The belt may be pre-stressed to a sufficiently high stress level to ensure that the stress to which the belt is subjected is not completely relieved, which may result in possible bending of the belt. The belt may also be pre-stressed to a sufficiently high stress level to ensure that the belt does not fall or leave the proportional region of the stress-strain curve when subjected to the torque for which the dynamometer test cell is designed.

According to the invention, the elastic band is subjected to a uniform tensile prestress in the longitudinal direction of the elastic band. This has the advantage that the material properties in the elastic band will be the same and the band will thereby react in a uniform manner to temperature changes. In this way, temperature variations will not otherwise affect the measurement results, and can be easily compensated for by the expansion coefficient, for example. If the belt is not subjected to a uniform tensile prestress but the prestress varies along the variations in the position of the belt, as is often the case, the material is subjected to different effects of temperature variations and is therefore difficult to compensate.

With respect to the elastic band, it is formed of high strength steel to support the high torque that the band may be subjected to. Thus, by physical definition, the band is elastic, i.e., the ability of the body to resist the twisting effects and to recover its original size and shape when the effect or force is removed.

Exemplary dimensions of the elastic band are 15-30cm in length and 3-7cm in width, although other dimensions may be suitable, for example, depending on the level of torque to be absorbed.

According to an embodiment of the invention, it is possible to subject the elastic band to a uniform tensile prestress in the longitudinal direction of the elastic band to some extent, so that the elastic band is also subjected to a uniform tensile prestress when being fixedly secured to the stator support but released from the stator, or the elastic band is also subjected to a tensile prestress when being fixedly secured to the stator but released from the stator support. That is, the elastic band may be securely fixed such that the pre-stress is already applied before the elastic band is fixed to the stator support and the stator.

According to an embodiment of the invention, for example, both ends of the elongated elastic band are fixedly secured to the stator or stator support, wherein a portion between both ends of the elastic band is fixedly secured to the other of the stator or stator support. The elastic band is still firmly fixed such that when the two ends are firmly fixed to the stator or stator support, the elastic band is tensile pre-stressed in its longitudinal direction when the portion between them is released from the other of the stator or stator support.

According to an embodiment of the invention, the elastic belt is subjected to a tensile prestress corresponding to at least the stress to which the elastic belt is subjected when the dynamometer test unit absorbs a first predetermined torque, wherein the first predetermined torque is the torque that the dynamometer test unit is designed to absorb and/or apply at most to the vehicle axle during the test. This may be, for example, the maximum torque that the power source of the dynamometer test unit is capable of delivering.

According to an embodiment of the invention, both ends of the elastic band are connected to the stator support, and wherein the central part of the elastic band is firmly fixed to the stator.

The tensile pre-stressing of the strip may be achieved by the action of a force acting in the longitudinal direction of the strip during assembly after one end of the strip has been fixed to one of the stator or the stator support and then a force is applied and the other end is fixed to said one of the stator or the stator support. In this way, the belt will become uniformly pre-stressed.

The torque measuring device may further include at least one pair of strain gauges fixed to the elastic band, the strain being measured by measuring a relative resistance difference applied by the strain gauges when the dynamometer test unit is subjected to torque.

The end portion of the strap may be fixedly secured to either of the stator and the stator support and its central portion may be fixedly secured to the other of the stator and the stator support. A first pair of strain gauges may be secured to the belt on one side of the central belt portion and a second pair of strain gauges may be secured to the belt on the other side of the central belt portion. The strain gauges are connected in an electronic measuring bridge circuit, such as a Wheatstone bridge, and can measure the force acting on the belt by measuring the relative resistance difference caused by the strain of the belt when torque is applied to the dynamometer test unit. One side of the belt will be subjected to reduced stress and the other side to increased stress relative to the central belt portion, the difference in stress resulting in a difference in resistance of the strain gauge proportional to the applied force, and thus the difference in stress proportional to the torque being experienced by the dynamometer test unit.

The stator may be supported by the stator bearing by the use of a tubular stator element, for example, forming part of the stator housing of the stator and journalled for rotational movement relative to the stator frame by a bearing assembly comprising at least two antifriction bearings.

In addition, the output shaft of the dynamometer test unit may be journaled for rotation relative to the stator through the use of antifriction bearings located within and concentric with the tubular stator elements.

The bearing assembly is disposed at or toward an end of the stator support that faces a vehicle to be tested during testing, wherein a greater portion of the power source, when carried by the bearing assembly, extends in cantilever fashion from the bearing assembly to an opposite side of the stator support.

The ground support may be configured to prevent the dynamometer test unit from tilting backwards when not attached to the vehicle.

According to an embodiment of the invention, at least two parallel elastic bands connect the stator to the stator support, thereby limiting the relative rotational movement between the stator and the stator support, the at least two parallel bands being configured to transmit forces between the stator and the stator support. In this way, the dynamometer test unit may be designed to absorb higher levels of torque.

The method may be performed in a vehicle dynamometer system where the dynamometer test unit is one having an electric machine as a power source.

The dynamometer test unit may also have a controllable hydraulic pump for controlling braking so as to apply braking torque to the axles of the vehicle during the test.

According to the present invention, the support means contacting the surface on which the dynamometer test unit is placed may comprise wheels, such as rotating wheels or castors, but may also comprise any other suitable means to enable the dynamometer test unit to be moved over the surface on which it is placed. According to the invention. The support device may be designed to provide relatively low friction relative to the movement of the dynamometer test unit to facilitate movement.

During dynamometer testing, any suitable sensor may be used to detect the rotational speed of the output shaft of the dynamometer test unit. According to an embodiment of the invention, in addition to determining the rotational speed, the rotational position may also be determined. For example, the shaft angular position may be determined using a suitable position determining device, such as one or more suitable encoders to detect the rotational position of the output shaft. For example, the shaft position determining device may include one or more absolute rotary encoders, one or more optical encoders, one or more hall effect sensors, or any other suitable sensor device to determine the rotational speed and angular position.

For example, the torque may be determined at a high sampling rate, for example 100 and 100000 times per second, using the means for measuring torque. The determined torque may then be associated with a current angle of rotation of the output shaft/axle of the dynamometer, which may be determined with a corresponding resolution. That is, for each torque value, the current rotational position may be determined separately at the instant the torque value is determined. The correlation values may then be used, for example, to determine whether certain rotational shaft angles produce different torque measurements. For example, if the dynamometer test cell is improperly set, e.g., with respect to alignment with the axle, the dynamometer test cell may exhibit undesirable vibrations that may affect the torque measurement. The correlation of the rotational angle of the shaft with the corresponding torque measurement can be used to detect such anomalies as well as other anomalies.

Furthermore, it may be desirable to measure the yaw moment experienced by the dynamometer test unit during steering movements about the yaw axis (i.e. the substantially vertical axis), for example when the vehicle steering mechanism performs a hubload steering movement, for example by turning the vehicle steering wheel, thereby turning the dynamometer test unit instead of the wheels.

The tape may also be used for this type of measurement according to embodiments of the present invention. In this case, in addition to measuring the strain in the longitudinal direction of, for example, an elongated belt, the strain to which the belt is subjected may also be measured in the transverse direction, and wherein the yaw moment may be determined from the strain. Similar to the description above regarding torque measurement, the steering motion of the dynamometer test unit will rise to a yaw moment (torque), with the result that the belt will be subjected to different levels of stress on either side (e.g., the middle portion) of the belt attached to the stator or stator support. The difference in strain on the belt may be detected and used to determine the yaw moment experienced by the dynamometer test unit (e.g., by turning the vehicle steering wheel) while steering.

According to an embodiment of the invention, the strain in the longitudinal direction as well as the strain in the lateral direction are used to determine the yaw moment experienced by the dynamometer test unit.

In addition, according to embodiments of the present invention, for example, a torque measurement device may be provided in a bearing housing supporting a dynamometer test unit power source to measure a bending moment experienced by the bearing when the dynamometer test unit is turned, for example, by a vehicle steering mechanism.

The bending moment experienced by the bearing can then be used to determine the yaw moment experienced by the dynamometer test unit.

The dynamometer test unit may also be of the type having two (or more) dynamometer power sources, one of which may be an electric motor, to provide power to the same axle, such as the axle half of a vehicle.

Other features of the present invention and its advantages will become apparent from the following detailed description of exemplary embodiments and the accompanying drawings.