DE102007026351B4 - test bench - Google Patents

Abstract

Test stand (1) for engine components, comprising: - a crankcase (2) for freely rotating reception of a crankshaft (3) with at least one crank pin (4); - A drive motor (6) for driving the crankshaft (3); and a cylinder (9) for receiving a piston (8), the cylinder (9, 9A, 10; 22; 23) and the piston (8) forming a closed gas space (11); - the piston (8) and the crankshaft (3) being connectable by means of a connecting rod (7), the connecting rod bearing (18) of which engages the crank pin (4); and - furthermore having a controllable gas feed line (13) into the gas space (11), - wherein the cylinder (9, 9A, 10; 22; 23) has an exchangeable cylinder head (10, 22, 23) so that differently shaped cylinder heads ( 10, 22, 23) can be used for testing, which define a different compression ratio by setting a volume of the gas space (11).

Description

The invention relates to a test stand for engine components, in particular conrod bearings, and a method for testing engine components.

For testing conrod bearings, a slide bearing test rig is known, in which a connecting rod acting on a smooth shaft is stressed by a hydropulser. There is a conrod bearing tester from Federal Mogul known in which a crankshaft via a connecting rod drives a piston running in a closed cylinder under a compression ratio of 2: 1. The disadvantage here is that, firstly, the compression ratio is fixed and second, there is a design-related upper speed limit of about 7000 U / min. In addition, the crankshafts used in this test bench from Federal Mogul must be crankshafts.

DE 44 34 695 A1 discloses a method and apparatus for testing an internal combustion engine having at least one cylinder having a reciprocating piston defining a variable volume combustion chamber communicating with intake and exhaust ports that are opened and closed by intake and exhaust valves, respectively. The combustion chamber of each cylinder is either emptied or the gas therein is compressed, depending on the test procedures to be performed, while the associated piston is moved up and down. The opening and closing of the valves in conjunction with the upward and downward movement of the associated piston results in the generation of pressure pulses which are detected and analyzed.

It is the object of the present invention to provide a possibility for realistic, comparatively inexpensive and easy-to-handle testing of engine components, in particular connecting rod bearings.

This object is achieved by a test stand according to claim 1 and a method according to claim 15. Advantageous embodiments are in particular the dependent claims.

A test stand according to one aspect of the invention comprises a crankcase for free-wheeling receiving a (built or original) crankshaft, wherein the crankshaft may have at least one crank pin, so is cranked. The test stand further comprises a drive motor for driving the crankshaft and at least one cylinder for receiving a piston, wherein the cylinder and the piston form a closed gas space. Piston and crankshaft can be connected by means of a connecting rod whose connecting rod bearing is seated on a crankpin of the crankshaft. This test rig thus simulates a fired internal combustion engine. By using the cranked crankshaft, a displacement path of the connecting rod is generated, which essentially corresponds to that in the course of the engine. In addition, realistic loads can be given up by the mass and gas forces, whereby z. B. Wear and wear patterns of the connecting rod bearing can be simulated realistically.

During operation, the piston in the cylinder is moved up and down by the movement of the crankshaft and compresses or depressurises correspondingly to the closed gas space. However, during each compression process, a small portion of the gas trapped in the gas space will escape, so that after a certain, and for example dependent on the compression pressure, number of revolutions of gas will escape from the gas space, that this can not build up sufficient gas pressure for realistic testing. This limits the test time of a test procedure. In order to increase the operating time and to be able to recreate a combustion chamber behavior of an internal combustion engine even more realistically, a gas supply into the gas space, which is controlled via a suitable control valve device with respect to their opening behavior, in particular controllable, is. Thus, by means of the control valve preferably a matched to the position of the connecting rod or the piston pressure profile can be applied to the gas space. This can be effective for the entire revolution or a part thereof. For example, at the bottom dead center, gas can be blown into the gas space in an abrupt manner. Alternatively, gas can be supplied to several times of a revolution, possibly also continuously with a certain pressure profile. The test rig is not limited to the supply of a particular gas, which may include, for example, air, nitrogen, helium or other suitable gases or mixtures thereof.

The cylinder head is also interchangeable. As a result, differently shaped cylinder heads can be used for the test, which define a different compression ratio by adjusting a volume of the gas space. For example, the cylinder head may be formed with a protruding into the cylinder / gas space projection (reduced gas volume), or with a cylinder / gas space outwardly extending recess (increased gas volume). This increases flexibility and ease of adjustment to real engine conditions.

Preferably, a gas supply to the gas space through the cylinder head and / or through a bore in the cylinder wall out, z. B. by means of a passage.

A test bench according to a further aspect of the invention comprises a crankcase for free-wheeling receiving a crankshaft with at least one crank pin; a drive motor for driving the crankshaft; and a cylinder for receiving a piston, wherein the piston and the crankshaft are connectable by means of a connecting rod, the connecting rod bearing acts on the crank pin, and wherein the cylinder is open, so in particular has no closed gas space.

The test stands preferably also have at least one controllable oil supply to the connecting rod bearing.

It is also advantageous for testing the connecting rod bearing when the test stand has a controllable oil supply line to the connecting rod bearing, whereby, for example, an influence of lubrication on the state of the connecting rod bearing can be tested. Controllable oil parameters are for example and preferably an oil pressure (eg between 0 and 10 bar) and an oil temperature (eg between -40 ° C and + 180 ° C, in particular between -30 ° C and + 150 ° C) ,

In the following, the invention is shown schematically in an embodiment in more detail.

1 shows a cross-sectional view in side view of a test stand according to a first embodiment;

2 shows a cross-sectional view in side view of a section of the test bench of 1 in the region of the cylinder housing according to a second embodiment;

3 shows a cross-sectional view in side view of a section of the test bench of 1 in the region of the cylinder housing according to a third embodiment.

1 shows a connecting rod tester 1 with a crankcase 2 in which a cranked crankshaft 3 with a crankpin 4 is stored free-spinning. The crankshaft 3 is via a speed and torque measuring flange 5 with a drive motor 6 connected. At the crankpin 4 grab a connecting rod 7 at, whose the crank pin 4 opposite end with a piston 8th connected in a cylinder 9 running. Through the cylinder 9 that is, its side walls and its cylinder head 10 will be together with the piston 8th a closed gas room 11 Are defined. In the cylinder 9 run cooling water holes 12 to the cylinder 9 cool when the piston 8th moved in it. Furthermore, here by the cylinder head 10 a compressed air hole 13 guided, which by a compressed air control valve 14 is controllable. Through the cylinder 9 continue to carry oil wells 15 to the crankshaft bearings 16 to be able to lubricate these. From the crankshaft bearing 16 again leads one in the crankshaft 3 located oil hole 17 to the connecting rod bearing 18 to provide it with oil. The connecting rod 7 is at the crankpin 4 by means of a spacer ring (only necessary with V-engine) 19 kept on location. On the drive motor 6 opposite side of the crankshaft 3 become signal lines 20 led out, which with sensors of the test bench 1 are connected and forward their signals. In a lower area of the crankcase 2 is also an oil drain 21 present to the camps 16 . 18 To remove leaking oil.

The test bench 1 simulates a fired internal combustion engine and works according to the two-stroke principle. After switching on the drive motor 6 This drives the crankshaft 3 which, in turn, the connecting rod 7 goes through its typical trajectory, which corresponds to a conventional engine curve. The resulting displacement track essentially corresponds to that during engine operation. This will cause the piston 8th in the cylinder 9 moves up and down and compresses or relaxes alternately the closed gas space 11 , To leaks of the gas space 11 and to achieve an even more realistic test, is done simultaneously by means of the control valve 14 an air pressure supply controlled, in particular regulated. In particular, during bottom dead center, air is introduced into the gas space 11 blown. Due to the height of the air pressure at bottom dead center and a corresponding compression ratio can also be the maximum combustion pressure from the engine operation. By means of the drive motor 6 applied speed adjust mass forces, and by the gas pressure, gas forces set. This represents a realistic load on the connecting rod bearing 18 , more precisely: on the connecting rod bearing shells, dar.

The test bench 1 is characterized by various advantages: plain bearing examinations are easy to represent. Experiments are possible in an early phase of engine development; Essentially, only the connecting rod, the bearing shells and possibly the crankshaft are needed. It can be both built and original crankshafts 3 or parts thereof are used for testing. So can the test bench shown 1 Many components even with a change of engine components, especially the crankshaft 3 and the connecting rod 7 , be maintained, for. B. the cylinder. The oil supply can also be controlled externally as desired.

The test bench 1 is thus suitable for testing engine components over a wide range of Influencing variables can be used. It can, for example, for off-axis conrod bearing testing their wear, Fress inclination, load capacity (fatigue), emergency running properties, contact patterns (rigidity at the connecting rod 7 ), new materials, an influence of a surface of the crankshaft 3 and / or an influence of a position of the oil supply hole uvm be examined. Furthermore, in a simple way, the connecting rod bearing 18 for example, with respect to a bearing shell geometry, a connecting rod geometry, a connecting rod surface (bore, honing,...), a connecting rod bearing surface (back and running surface), a connecting rod bearing clearance, connecting rod bearing material specifications, a crank pin surface of the crankshaft (built crankshaft) or with respect to the location of the connecting rod oil supply hole 17 (built crankshaft). At the test bench shown 1 For example, the following sizes are adjustable: an oil pressure of 0 to 10 bar, an oil volume flow reduction of 0 to 1 l / min, an oil temperature of -30 to + 150 ° C, the type of oil, a speed up to 13,000 min ^-1 , a load (gas pressure , Mass force) up to approx. 125 bar or up to approx. 55 KN and / or an addition of media in the oil (eg dirt, fuel, water). Measurable process variables include, for example: a cylinder pressure waveform, an oil pressure in the oil supply, an oil pressure in the oil supply hole in the crankshaft before entering the bearing, an oil temperature in the oil supply, an oil temperature in the oil supply hole in the crankshaft before entering the bearing, an oil volume flow measurement, a Temperature at the connecting rod bearing shell back, a temperature at the main bearing shell back, a connecting rod force, a torque and / or a rotational speed. An original crankshaft ensures a realistic oil supply. In contrast, a built-up crankshaft, in particular, can provide variable surface roughnesses, variable surface geometries, and a variable location of the oil supply well.

2 shows a part of the test bench 1 from 1 in the area of the cylinder head 22 according to a second embodiment. The replaceable cylinder head 22 now in the direction of the gas space 11 designed so that he is in the cylinder 9 protrudes and so the volume of the gas space 11 compared to the execution of 1 reduced. As a result, a higher compression ratio can be simulated. The gas supply 13 is also in this embodiment by the cylinder head 22 guided.

3 shows a part of the test bench 1 from 1 in the area of the cylinder head 23 according to a third embodiment. Now has the interchangeable cylinder head 23 at the gas room 11 a recess on, reducing the volume of the gas space 11 compared to the execution of 1 is enlarged. As a result, a lower compression ratio can be simulated. The gas supply 13 is also in this embodiment by the cylinder head 23 guided.

By varying the headspace volume, a simulation of a real fired engine can be performed even more realistically.

Of course, the present invention is not limited to the embodiment shown, but only determined by the scope of the appended claims. For example, instead of air, nitrogen can also enter the gas space 11 be introduced. Also, the test bench can be extended to the use of a crankshaft with more than one crank pin. Also, measured data can be telemetrically delivered to the outside. Also, the cylinder cover can be removed and the piston or the connecting rod so that without closed gas space and consequently also without influence of a gas force, so only by inertial forces are moved.

Also, the location of the oil (supply) holes is not limited to the arrangement shown and need z. B. are not performed by the cylinder housing. Furthermore, the gas supply does not have to be guided through the cylinder head, but can also be guided, for example, through a cylinder wall and comprise a plurality of individual supply lines. In addition, a closed and variably dimensioned gas space can also be achieved other than by attaching a cylinder head, z. B. by introducing a height-adjustable insert in an upwardly open cylinder, z. B. a closely fitting reciprocating piston.

LIST OF REFERENCE NUMBERS

1

Pleuellagerprüfstand

2

crankcase

3

crankshaft

4

crank pins

5

flange

6

drive motor

7

pleuel

8th

piston

9

cylinder

9A

cylinder housing

10

cylinder head

11

headspace

12

Cooling water hole

13

Compressed air hole

14

Pneumatic control valve

15

Oil supply hole

16

crankshaft bearings

17

oil well

18

connecting rod bearing

19

spacer ring

20

signal lines

21

oil drain

22

cylinder head

23

cylinder head

Claims (18)

Test bench ( 1 ) for engine components, comprising: - a crankcase ( 2 ) for free-wheeling receiving a crankshaft ( 3 ) with at least one crank pin ( 4 ); A drive motor ( 6 ) for driving the crankshaft ( 3 ); and a cylinder ( 9 ) for receiving a piston ( 8th ), whereby the cylinder ( 9 . 9A . 10 ; 22 ; 23 ) and the piston ( 8th ) a closed gas space ( 11 ) form; - the piston ( 8th ) and the crankshaft ( 3 ) by means of a connecting rod ( 7 ) are connectable, the connecting rod bearing ( 18 ) on the crankpin ( 4 ) attacks; and - further comprising a controllable gas supply line ( 13 ) into the gas space ( 11 ), Wherein the cylinder ( 9 . 9A . 10 ; 22 ; 23 ) a replaceable cylinder head ( 10 . 22 . 23 ), so that differently shaped cylinder heads ( 10 . 22 . 23 ) can be used for the test, a different compression ratio by adjusting a volume of the gas space ( 11 ) define. Test bench ( 1 ) according to claim 1, wherein the gas space ( 11 ) through side walls of the cylinder ( 9 ), the replaceable cylinder head ( 10 . 22 . 23 ) and the piston ( 8th ) is formed. Test bench ( 1 ) according to claim 2, wherein the gas supply line ( 13 ) to the gas space ( 11 ) through the replaceable cylinder head ( 10 . 22 . 23 ) is guided. Test bench ( 1 ) according to one of claims 2 or 3, which with removed cylinder head ( 10 . 22 . 23 ) is operable. Test stand according to one of the preceding claims, further comprising a controllable oil supply ( 15 . 17 ) to the connecting rod bearing ( 18 ). Test bench ( 1 ) according to claim 5, wherein an oil pressure, an oil temperature and / or an addition of media in the oil is adjustable. Test bench ( 1 ) according to one of claims 5 or 6, wherein an oil volume flow reduction of 0 to 1 l / min is adjustable. Test bench ( 1 ) according to one of the preceding claims, in which the crankshaft ( 3 ) is interchangeable. Test bench ( 1 ) according to one of the preceding claims, in which the crankshaft ( 3 ) is a built crankshaft. Test bench ( 1 ) according to one of the preceding claims, in which the connecting rod ( 7 ) is interchangeable. Test bench ( 1 ) one of the preceding claims, which is operable according to the two-stroke principle. Test bench ( 1 ) one of the preceding claims, wherein the test bench ( 1 ) is arranged to at a bottom dead center gas through the gas supply line ( 13 ) into the gas space ( 11 ). Test bench ( 1 ) one of the preceding claims, wherein the gas supply line ( 13 ) for a supply of gas into the closed gas space ( 11 ) to compensate for leaks in the gas space 11 ) is provided. Test bench ( 1 ) according to one of the preceding claims, which is a test rig for testing connecting rod bearings ( 18 ). Method for testing engine components, in which a cranked crankshaft ( 3 ) by means of a drive motor ( 6 ), wherein the crankshaft ( 3 ) via a connecting rod ( 7 ) one in a cylinder ( 9 . 9A . 10 ; 22 . 23 ) running piston ( 8th ), whereby the cylinder ( 9 . 9A . 10 ; 22 . 23 ) and the piston ( 8th ) a closed gas space ( 11 ) and wherein the connecting rod ( 7 ) via connecting rod bearings ( 18 ) on a crankpin ( 4 ) of the crankshaft ( 3 ), and wherein a gas supply into the gas space ( 11 ), wherein one of the gas space ( 11 ) limiting cylinder head ( 10 ; 22 ; 23 ) is changed to set a compression ratio. Method according to claim 15, in which gas at a bottom dead center into the gas space ( 11 ) is blown. Method according to one of claims 15 to 16, wherein an oil pressure, an oil temperature, and / or an addition of media in the oil are adjusted. Method according to one of claims 15 to 17, wherein an oil volume flow reduction of 0 to 1 l / min is set.

Images