DE102006026859B4 - Device and method for determining the friction on a chain - Google Patents

Abstract

Device (1) for determining the coefficient of friction (μ) on a chain (2), with a chain wheel (3) which is arranged on a drive shaft (4), via which the chain (2) can be driven, a tensioning rail (5) via which the chain (2) can be tensioned by means of a pretensioning force (Fv), a torque measuring shaft (13) which is connected to the drive shaft (4), so that the friction coefficient (μ) is determined by the torque (M) of the torque measuring shaft (13 ), the preload force (Fv), a radius (r) of the sprocket (3) and a wrap angle (β) of the tensioning rail (5) can be determined.

Description

Technical area

The invention relates to a device and a method for determining the friction coefficient on a chain according to the preamble of claims 1 and 9.

State of the art

The DE 1 648 624 B shows a test bed for V-belt, rope or chain drives with two mounted in a frame on a support frame in bearing blocks and spaced apart adjustable waves to which test discs are attached, over which the sample runs, while the one shaft also with a belt drive a drive motor is connected, and with a tensioning device for the DUT.

The drive motor consists of a DC machine, and the other shaft is connected via a further belt drive, which is arranged as the one belt drive on each side of the two shafts, with a DC load machine. The two DC machines are placed on two rockers below the support frame and the tensioning device comprises a tension pulley mounted on a height-adjustable platform below the two pulleys acting as the third pulley, and the pulleys attached to the other side of the two shafts are interchangeable.

On the basis of the measured armature currents, the armature voltage and the excitation power, the transmitted power, minus the previously determined no-load losses, can be determined.

From the US 4,413,513 A . US 4,274,278 A . US 3,385,096 A. and US 5,689,067 A Methods and apparatus for testing chains are known, in which case no coefficient of friction is determined.

Object of the invention

The invention has for its object to provide an apparatus and a method, so that the parameters for measuring the coefficient of friction on a chain are independently variable and measurable.

Solution of the task

The object is achieved by a device according to claim 1 and a method according to claim 9.

Advantages of the invention

An advantage of the invention is that the factors influencing the coefficient of friction can be exchanged and varied independently of one another. The influencing factors include, for example, the material of the tensioning rail, the surface structure of the tensioning rail, the material of the chain, the temperature of the lubricant, the lubricant quantity, the wrap angle and the radius of the tensioning rail as well as the ambient temperature.

In an advantageous embodiment of the invention, the biasing force via weights / mass, which are arranged on a receiving element of a lever system generated. This offers the great advantage that, for example, with finely graduated load steps even the slightest friction differences between the friction partners can be determined very accurately.

In a further advantageous embodiment of the invention, the distance between the sprocket and the clamping rail is variable. This offers the advantage that no further disturbances occur due to the unhindered chain run. Also in the future one can be meaningful to "clocked lubrication" of the traction mechanism and a so-called minimum lubrication can be determined.

Another advantage of the device according to the invention is that it can be connected to different drives. In addition, the solution according to the invention forms the basis, in the future also other traction drives, such as timing belts with special requirements of media compatibility and tension / guide elements to check for friction and to determine.

The drive train of the device comprises a safety clutch to protect the drive from overload, a metal bellows coupling to compensate for axial, lateral and angular differences between the drive and the drive train, and a torque measuring shaft for determining the torque occurring.

In an advantageous embodiment of the invention, the drive shaft in the device via a deep groove ball bearing can be stored. The deep groove ball bearing offers the advantage of low friction.

M steht für Drehmoment in [Nm], r_Kettenrad für Radius des Kettenrads in [m], Fv für Vorspannkraft in [N] und β für Umschlingungswinkel in [°]. Diese Parameter sind der Vorrichtung entnehmbar.The friction coefficient μ of the chain is determined as follows: $\mu =\frac{\text{ln}\left(\frac{M}{r_{Kettenrad}*F_V}+1\right)}{\beta }\text{,}$

M stands for torque in [Nm], r _sprocket for radius of the sprocket in [m], Fv for preload force in [N] and β for wrap angle in [°]. These parameters are removable from the device.

The coefficient of friction can be determined very precisely with the device and the method according to the invention, since possible interference variables, for example the friction of the drive shaft in the bearing or the axial, lateral and angular differences between drive and drive train, are minimized.

• - anliegende Vorspannkraft an der Spannschiene,
• - unterschiedliche Spannschienenmaterialien,
• - unterschiedliche Spannschienengeometrie (Umschlingungswinkel, Radius),
• - unterschiedliche Werkstoffpaarungen der Kettenlaschen und des Gleitbelags, welcher auf der Spannschiene angeordnet ist,
• - Oberflächenrauheit und Größe der Kontaktflächen von Kettenlaschen und Gleitbelag,
• - Temperatur des Schmiermittels im Gehäuse und an den Reibstellen,
• - Verschleißverhalten des Gleitbelags an der Kette,
• - Schmiermittelmenge,
• - Art der Schmierung,
• - Temperatur-Viskoseverhalten des Schmiermittels,
• - unterschiedliche Werkstoffpaarung von Kettenbolzen und Kettenrad,
• - unterschiedliche Radien des Kettenrads,
• - unterschiedliche Kettenarten.

By means of the device and the method according to the invention, for example, the following influences on the friction coefficient μ can be determined:

• - applied preload force on the tensioning rail,
• - different tensioning rail materials,
• different clamping rail geometry (wrap angle, radius),
• - Different material pairings of the link plates and the sliding lining, which is arranged on the clamping rail,
• Surface roughness and size of the contact surfaces of link plates and sliding lining,
• - temperature of the lubricant in the housing and at the friction points,
• - wear behavior of the sliding lining on the chain,
• - amount of lubricant,
• - type of lubrication,
• Temperature-viscose behavior of the lubricant,
• different material combination of chain pin and sprocket,
• different radii of the sprocket,
• - different types of chains.

The device according to the invention and the method is particularly suitable for chains for driving control drives or ancillary components of internal combustion engines, the tensioning rails of the device are suitable for such a chain drive. With the device and the method, it is possible to optimize a chain drive in terms of material selection, geometric dimensioning and lubrication, since all parameters are independently variable and can be determined.

list of figures

• 1: eine Vorderansicht auf eine erfindungsgemäße Vorrichtung;
• 2: eine Seitenansicht der Vorrichtung gemäß 1;
• 3: eine perspektivische Ansicht auf die Vorrichtung gemäß 1.

Show it:

• 1 a front view of a device according to the invention;
• 2 a side view of the device according to 1 ;
• 3 a perspective view of the device according to 1 ,

In the 1 to 3 is a device according to the invention 1 shown. A chain 2 is over a sprocket 3 drivable, the sprocket 3 on a drive shaft 4 is arranged. The chain 2 will over a tensioning rail 5 cocked, with the tensioning rail 5 on a lever system 6 is arranged over the weights 7 by means of a receiving element 8th can be included to a biasing force Fv for the chain 2 to create. The wrap angle β the tensioning rail 5 is in this embodiment 180 °, which is variable. On the tensioning rail 5 is a sliding coating 9 arranged, for example screwed or clipped. The lever system 6 is in balance if no mass / weights 7 on the receiving element 8th are attached.

The lever system 6 includes a tensioner rod 10 , a tensioner joint 11 and a tensioner lever 12 , The main body of the tensioning rail 5 is with the tensioner rod 10 , For example, by two threaded bolts connected.

A torque measuring shaft 13 is with the drive shaft 4 via a safety coupling 14 connected. The torque measuring shaft 13 has, for example, a nominal torque of 5 Nm, an accuracy of <0.1% and a maximum speed of 2000 rpm. The safety clutch 14 serves to protect the drive against overload.

The drive shaft 4 further comprises a metal bellows coupling 15 to compensate for axial, lateral and angular differences between a drive, not shown, and the drive train (metal bellows coupling 15 , Torque measuring shaft 13 and safety coupling 14 ).

The lubrication of the chain 2 done via nozzles 16 where lubricant is applied under pressure to the chain inlet.

To make an optical assessment during the operation of the device 1 to be able to give are slices 17 , For example, from polymethyl methacrylate, as Einhausung 18 the chain drive side provided. The disc 17 is on a window frame 19 glued to increase the stiffness. The window frames 19 for example, by knurled screws with the test bench frame 20 connected and allow a quick assembly and disassembly. The sealing of the enclosure 18 in the area of the drive shaft 4 done with a radial shaft seal. In the area of the discs 17 the seal is done with a round cord, which in a groove in the window frame 19 glued and to the test bench frame 20 is pressed. In the area between the test bench cover 21 and tensioner rod 10 becomes the device 1 with a sealing bellows 22 sealed.

LIST OF REFERENCE NUMBERS

1

contraption

2

Chain

3

Sprocket

4

drive shaft

5

tensioning rail

6

lever system

7

Weight

8th

receiving element

9

sliding lining

10

tensioner rod

11

Spanner joint

12

release lever

13

Torquemeter

14

safety clutch

15

Metal Bellows

16

jet

17

disc

18

housing

19

window frame

20

test frame

21

test cap

22

sealing bellows

Fv

preload force

M

torque

β

Wrap angle

μ

friction

rKettenrad

Radius sprocket

Claims (9)

Device (1) for determining the coefficient of friction (μ) on a chain (2), with a chain wheel (3) which is arranged on a drive shaft (4), via which the chain (2) can be driven, a tensioning rail (5) via which the chain (2) can be tensioned by means of a pretensioning force (Fv), a torque measuring shaft (13) which is connected to the drive shaft (4), so that the friction coefficient (μ) is determined by the torque (M) of the torque measuring shaft (13 ), the biasing force (Fv), a radius (r _sprocket ) of the sprocket (3) and a wrap angle (β) of the tensioning rail (5) can be determined. Device (1) according to Claim 1 , characterized in that the clamping rail (5) on a lever system (6) is arranged, wherein the lever system (6) comprises a receiving element (8) for weights (7). Device (1) according to Claim 1 or 2 , characterized in that the distance between the clamping rail (5) and the sprocket (3) is variable. Device (1) according to at least one of the preceding claims, characterized in that the torque measuring shaft (13) via a safety coupling (14) with the drive shaft (4) is connectable. Device (1) according to at least one of the preceding claims, characterized in that the drive shaft (4) comprises a metal bellows coupling (15). Device (1) according to at least one of the preceding claims, characterized in that the drive shaft (4) by means of a deep groove ball bearing in the device (1) can be stored. Device (1) according to at least one of the preceding claims, characterized in that the clamping rail (5) comprises a sliding lining (9). Device (1) according to at least one of the preceding claims, characterized in that the chain (2) by means of nozzles (16) is lubricated. Method for determining the coefficient of friction (μ) on a chain (2), characterized in that the torque (M) of a torque measuring shaft (13) is measured, this being connected to a drive shaft (4) via which the chain (2) connected to the drive shaft (4) arranged sprocket (3) is connected, the biasing force (Fv) of a tensioning rail (5) over which the chain (2) is stretched, is measured, the coefficient of friction (μ) on the torque ( M) of the torque measuring shaft (13), the biasing force (Fv), a radius (r _sprocket ) of the sprocket (3) and a wrap angle (β) of the tensioning rail (5) is determined.

Images