RU23503U1 - CAR FASTENING SYSTEM ON A DYNAMIC STAND WITH RUNNING DRUMS (OPTIONS) - Google Patents

Description

h SYSTEM OF FASTENING A CAR ON A DYNAMIC STAND WITH RUNNING DRUMS (OPTIONS) The utility model relates to devices used in the technique of experimental design work (R&D) during research and development of wheeled vehicles, in particular automobiles. During bench tests to study the noise of a car in a semi-anechoic acoustic chamber on a dynamic bench with running drums, a special car mount system is used. holding the car from its spatial movement (hereinafter the mounting system). This mounting system is a set of holding flexible cables with a tension mechanism in the form of four electric winches installed under the camera floor in the engine room of the test chamber. A car mounted on a dynamic stand is secured by cables to towing hooks (eyes, hooks). The cables, acting as tension elements, through the swivel plates of the stand winches mounted on the floor, are installed on the drums of the winches. The applied vehicle fastening system creates an additional vertical (downward) load to the vehicle weight directly perceived by the car chassis elements, causes additional tire deformation and an increase in the area of contact of the tire with the surface of the running drum, which, as a result, leads to increased specific tire noise, significantly different in level and spectrum of radiation from the noise of the tires when they are freely rolling on the road surface during the movement of the car. To a particular extent, the negative consequences of this test method affect the asymmetric arrangement of the towing hook of the car relative to the longitudinal axis of the car (for one of the longitudinal side members of the body). In this case, in addition to the problems of the appearance of intense specific noise of tires on a stand with running drums (especially tires located on the side of the towing hook), there is a problem of lateral withdrawal of a car from

surfaces of rotating cross-country f - p-GaHCp test benches at slow speed / soon:; rotation of the drums (simulating a high speed car). This problem is associated with the safe operation of the stand and the safe working conditions of the operators involved in the process of testing the car.

There is also a problem of changing (deteriorating) the traction and speed properties of a car when using this system of fastening a car on a drum stand. This is clearly seen if we consider the dynamics of the automobile wheel when it is rolling along the undeformable surface of the drum. From the side of the car, the following forces act on the wheel; normal load of the wheel PZ, the longitudinal force of the wheel Px and the moment M supplied from the vehicle axle. From the side of the running surface of the running drum, reactions occur: normal reaction Rj, longitudinal reaction RV The equation of motion of the wheel relative to its center:

where GLK is the mass of the wheel, j is the acceleration of the wheel.

The main force driving the car is the RX reaction on the drive wheels, which is created by using the power (effective torque on the shaft) of the engine. From the theory of operational properties of a car, an expression of the RX reaction is known taking into account the loss of rolling wheels:

Rx M / rK-fRz-U / r /, where Gk is the kinematic radius of the wheel;

f is the coefficient of rolling resistance of the wheel;

IK is the moment of inertia of the wheel relative to its axis of rotation. When the wheel of the car is fixed, fixed from movement on the stand, there is no movement of the wheel along the surface of the drum in a direction perpendicular to the axis of rotation. Therefore, RZ P can be considered. Therefore, with an increase in the normal load on the wheel, which is created by the applied vehicle fastening system, the component of power losses on wheel rolling (fRz) increases, which significantly distorts the real traction-speed and vibration-acoustic properties of the car.

From application DE 19916699 A1, IPC G01M 17/00, publ. 11/30/2000, the applicant f. AUDI AG, a known device for bench testing of cars on running drums, which provides a fixed position of the car on the running drums, excluding eo as longitudinal

TC RX-PX,

as well as lateral displacements, which is ensured by the use of rigid longitudinal and transverse couplers containing threaded adjusting inserts, rods with a screw part and locking assemblies with swivel joints. The hinge thrust housings are rigidly mounted in the floor structure of the test room in which the stand is located. The disadvantage of this design is the use of rigid (without compliant elastic and damping elements) restrictive bonds between the vibrating body (body) of the car and the chamber floor, distorting the vibro-acoustic characteristics of the body, which is undesirable for their use in acoustic semi-anechoic test chambers. In this case, / dynamic excitation (vibration) from the body of the body, the elements of the car’s chassis is transmitted through the vibration-conducting elements of the restrictive fastening connections to the camera floor, causing it to vibrate and the corresponding spurious noise radiation, distorting the real acoustic field of the studied object (car). On the other hand, the imposition of rigid force-limiting constraints and their effect on the power frame of the body changes the real vibro-acoustic characteristics of the body, which is undesirable when conducting high-quality vibro-acoustic studies of a car in an acoustic chamber equipped with running drums. In addition, the absence of flexible damping links in the structure of restrictive bonds does not allow for the following compensating maintenance of a constant effort to keep the car on the bench (tracking reaction) at unsteady test modes (acceleration, braking) of the car, which often leads to additional impulse loads, like the test vehicle, as well as on the elements of the vehicle mounting device on the stand, which is ultimately associated with a change in the vibro-acoustic characteristics of the test The object (car).

As a prototype, a system for mounting a car on a dynamic stand with running drums, described in US patent No. 3520180, MPKS01M7 / 00, 17/04, publ. 07/14/1970. The system contains, in particular, six racks with electric winches kinematically connected by means of flexible elements (cable extensions) to the car body. Racks designed to exclude the vertical component of the power load from the mounting system due to the horizontal installation of the mounting branches

elements (cables) that close the vertical blocks with towing hooks of the car (one strut located at the front and rear of the car) and to exclude the lateral displacement of the car, two pairs of struts - located to the right and left of the car body in the areas of the front and rear bumpers, designed for exclusion of lateral drive car. The latter are located in the areas of the planes of the front and rear bumpers of the car, i.e. in areas of direct direct sound emission by tires, engine compartment and exhaust pipe cut (in the planes of the bumpers). This creates additional sound-reflecting effects from massive surfaces of the racks and distortion of the real sound field of a moving car on a motorway, which is undesirable for high-quality objective measurements of the external and internal noise of the car in an acoustic semi-anechoic chamber with running drums on which the car under study is mounted. On the other hand, such a system of fastening a car to a drum stand requires the use of a large number of links for adjusting the tension of the cables of six electric winches with the corresponding brake devices.

The essence of the utility model lies in the fact that in the known system of fastening a car on a dynamic stand with running drums, it contains a car mounted on running drums, equipped with towing hooks front and rear, the spatial movement of which is due to retaining flexible elements fixed in mounting devices mounted on the floor of the stand , the latter are made in the form of two pairs of fixed vertical swivel racks located in pairs relative to the front and rear parts of the body va car audio Lara and movable along the longitudinal axis of the car racks; non-moving vertical rotary racks are equipped with blocks rotating in horizontally located axes, and the axes of the blocks are mounted with the possibility of selective sampling and fixing along the height of the rack; movable racks are mounted in front of the car, in grooved rails, the distance between which exceeds the width of the car body, with the possibility of selective installation and rigid fixation and are equipped with blocks rotating in vertical axes, and the blocks have the ability to be fixedly moved along the height of the rack; branches of flexible elements are fixed in front and behind the car to a single towing hook; movable racks are located between the towing hook v and the stationary racks, so that the branches of the flexible elements form an obtuse angle with the apex in the vertical axis of the movable rack block. In another embodiment of the design of the vehicle mounting system on a dynamic stand with running drums, comprising a vehicle mounted on running drums, provided with front and rear towing hooks, the spatial movement of which is limited by retaining flexible elements fixed in mounting devices mounted on the floor of the stand, the latter are made in the form two pairs of fixed vertical swivel racks located in pairs relative to the front and rear parts of the car body I; fixed vertical rotary racks are equipped with blocks rotating in horizontally located axes, and the axes of the blocks are mounted with the possibility of selective sampling and fixing along the height of the rack; branches of flexible elements are fixed in front and behind the car to twin towing hooks; at the same time, at least on one of the sides of the car, the branches of the thin elements intersect each other. In this embodiment of the system, the fastening devices may additionally comprise a pair of racks movable in the direction of the longitudinal axis of the car which are mounted in front of the car in grooved rails, the distance between which exceeds the width of the car body, with the possibility of selective installation and rigid fixation and are equipped with blocks rotating in vertical axes Moreover, the blocks have the possibility of a fixed movement along the height of the rack; movable racks are located between the towing hook and the stationary racks, so that the branches of the flexible connection form an obtuse angle with the apex in the vertical axis of the block of the movable rack. With these (both) versions of the fastening system, it is also possible to remove the fastening posts from the areas of direct investigation of the sound field of the car in the zones of characteristic noise emitters - tires, intake, exhaust - to the left and right of the longitudinal axis of the car, as required by international measurement standards external vehicle noise according to UNECE Regulation No. 51 (7.5 m from the longitudinal axis of the vehicle).

Figure 1 shows the first variant of the inventive system of fastening a car on a dynamic stand with running drums.

Figure 2 shows stationary racks with a horizontal axis of the roller block.

On Fig.3 shows a movable stand with a vertical axis of the roller block.

Figure 4 shows a diagram of the forces and moments acting on the automobile wheel when it is rolling along the non-deformable surface of the drum.

Figure 5, 6 and 7 show some options for the location of the branches of flexible connections (extensions) in the proposed options for the design of the system.

The positions in figures 1-4 show:

1- test vehicle

2- running drums

3- flexible element (fixing cable)

4- rotatable mounting plate

5- the base of the stand guide

6- movable rack

7 - motionless (stationary) rack

8- clamping plate (base) of the movable stand

9- groove guide rail

10- stiffener

11- axis of the block

12-block (pulley) 13-limiter

14- hole for cable exit

15- bracket for mounting the block (pulley)

16- electric winch

17- towing hook

Blocks 12 have the ability to adjust the height of their axis of rotation 11 and are set at the level of the towing hooks 17 (hooks, eyes) of the car. Stationary racks 7 are bolted to the standard, floor-mounted rotary mounting plates 4 of the bench mounting system of the car. The movable racks 6 are mounted in the grooves 9 of the base 5 of the guide rails using the pressure plates 8 and have the ability to move and lock in the desired mounting point at a given distance from the body (from the towing hook 17). The groove guides 9 are parallel to the longitudinal axis of the car, and the distance between them exceeds the width of the car body. The proposed fastening system, by installing the fastening branches of the flexible elements (cables) 3 in a horizontal position and the corresponding distribution of forces and reactions in the fastening system, deflects the wheels of the car from an additional normal (clamping) load, which, therefore, to a lesser extent deforms the tire structure and to a lesser extent distorts the area of the contact spot of the tire with the surface of the running drum 2, which, as a result, eliminates the amplified specific noise of the tires, different from the noise of the tire when it is freely rolling in Leave your car on the road surface. Also, additional power (deformation) losses of the tire structure during the rolling process of the wheel will not occur, and, accordingly, the traction and speed properties of the car will be less distorted. In addition, through the use of movable racks 6 with a horizontal arrangement of blocks 12 at a given height from the floor of the chamber and providing an obtuse angle formed between the branches of flexible elements 3 (cable) connecting the towing hook 17 with horizontal blocks 12, a predetermined value of the transverse component of the force is provided that keeps the car from lateral withdrawal with a lateral (asymmetric) arrangement of the towing hook 17, deploying the car (dropping the car from the running drums at a high speed of running oh drums). In the proposed system of fastening a car on a dynamic stand with running drums, it is possible to minimize the unfolding moment acting on the car relative to the axis normal to the plane passing through the axis of rotation of the front and rear wheels, and striving to change the directional stability of the car (otherwise, the front of the car throws off the surface of the drums 2). This moment is reduced due to the location of flexible elements 3 (stretching branches) of the fastening system at an angle of more than 90 ° to each other and an increase in the angle between the force vectors that create the unfolding moment relative to the longitudinal axis of the car.

Claims (3)

1. The car mounting system on a dynamic stand with running drums, comprising a vehicle mounted on running drums, equipped with front and rear towing hooks, the spatial movement of which is limited by holding flexible elements fixed in mounting devices mounted on the floor of the stand, characterized in that the mounting devices are made in the form of two pairs of stationary vertical swivel racks located in pairs relative to the front and rear parts of the car body, and one are arrays of racks movable in the direction of the longitudinal axis of the car, fixed vertical swivel racks are equipped with blocks rotating in horizontally located axes, and the axes of the blocks are mounted with the possibility of selective selection and fixing along the height of the racks, movable racks are mounted in front of the car in grooved rails between which the width exceeds the car body, with the possibility of selective installation and rigid fixation and are equipped with blocks rotating in the vertical axes, and the blocks are possible st fixed displacement adjustment rack, branches of the flexible elements are fixed in front and behind a single towing vehicle to the hold, the movable rack are arranged between the towing hook and the fixed rack so that the branches of the flexible elements form an obtuse angle with the apex at the vertical axis of the movable rack unit.  2. The car mounting system on a dynamic stand with running drums, comprising a vehicle mounted on running drums, equipped with towing hooks at the front and rear, the spatial movement of which is limited by holding flexible elements fixed in mounting devices mounted on the floor of the stand, characterized in that the mounting devices are made in the form of two pairs of stationary vertical swivel racks located in pairs relative to the front and rear parts of the car body, motionless vertical swivel racks are equipped with blocks rotating in horizontally located axes, and the axes of the blocks are mounted with the possibility of selective selection and fixing along the height of the rack, the branches of flexible elements are fixed in front and behind the car to paired towing hooks, while at least on one side of the car branches flexible elements intersect each other. 3. The system according to claim 2, characterized in that the mounting devices further comprise a pair of racks movable in the direction of the longitudinal axis of the car, which are mounted in front of the car, in grooved rails, the distance between which exceeds the width of the car body, with the possibility of selective installation and rigid fixation and equipped with blocks rotating in vertical axes, and the blocks have the possibility of fixed movement along the height of the rack, movable racks are located between the towing hook and the stationary racks that them that the flexible connection branches forming an obtuse angle with the apex at the vertical axis of the movable rack unit.