DE102008036042A1 - Pulse generation unit for generating pulsed gasflow from unpulsed gasflow, has armature for rotatory opening and closing of gas channel between gas inlet and gas outlet - Google Patents

Abstract

The pulse generation unit (6) has an armature (8) for rotatory opening and closing of gas channel (7) between the exhaust gas inlet (13) and exhaust gas outlet (14). The gas inlet is provided for supplying the unpulsed gas flow, and the gas outlet is provided for discharging the unpulsed gas flow. The armature has a rotary disk valve with a freely rotable connection body. Independent claims are included for the following: (1) a dynamometer, particularly exhaust-gas turbocharger with a pulse generation unit; and (2) a method for operating the dynamometer.

Description

The The invention relates to a pulse generating unit for generating a pulsed gas stream from a substantially unpulsed gas stream and a so equipped Test bench.

to Measurement of exhaust gas turbochargers is a test bench ("loader test bench") known in which the survey stationary takes place by an application by a constant exhaust gas mass flow done by a stationary operated combustion chamber is generated, which a stationary compressor is downstream. As a result, stationary measured maps become more relevant Parameter values generated.

dynamic Effects, as in reality Engine operation occur and the one big impact in particular have on the response of the exhaust gas turbocharger, are metrologically not recorded and can at an initial design previously only by means of correction factors to the stationary measured Maps considered be based on experience. Also for a design of the turbocharger in the early Development phase, the correction factors are used. The effect A realistic exhaust gas dynamics can only be assessed on the engine test bench become. This is associated with considerable effort and only in one later Development phase possible. Also an interaction of the chain: manifold / flange / turbine (or Twinscroll turbine) as well as the impact of leaks in this Chain can also only on the engine test bench be rated.

It The object of the present invention is a possibility for testing of vehicle components taking into account a realistic To provide exhaust dynamics, which is relatively inexpensive and also in an early one Development stage can be applied.

These Task is by means of a pulse generating unit, a test bench and a method for operating a test bench according to the respective independent claim solved. Preferred embodiments are in particular the dependent ones claims removable.

The Pulse generating unit is used to generate a pulsed gas flow from a substantially unpulsed gas stream. For this purpose, the pulse generating unit at least one fitting for alternately opening and closing at least a channel between at least one inlet gas inlet the unpulsed gas stream and at least one gas outlet for discharging of the pulsed gas flow. By the alternating opening and close the gas volume flow / gas pressure is held up alternately at the gas outlet and lowered, resulting in the pulse-like gas flow. By the characteristics of the valve, z. B. the speed of change between an open one and a blocking state, the flow area, the type of Fitting, etc., the shape of the pulses is significantly influenced. Thereby Is it possible, already in early Development phases real onflow conditions a loader on inexpensive Kind of simulating.

Basically the pulse generating unit is not limited to a specific number or type limited by fittings. Thus, at least one valve as valve, slide, rotary valve (Cock) and / or flap present. It becomes too fast and robust circuit However, a pulse generating unit preferred in which the fitting includes a rotary valve.

Of the closing component the rotary valve is preferably freely rotatable, d. he, that he is continuously rotating (without stop) is rotatable and thus open and Shut down does not need to be turned in opposite directions. This allows a very fast alternate opening and closing a fast rotational movement of the Abschlusskör pers be achieved, what for a replica an exhaust flow from an internal combustion engine is advantageous.

It is used in particular for generating at least two separate pulsers gas flows a pulse generating unit preferably, the at least two fluidically separate gas channels having. Each gas channel has at least one gas inlet and one Gas outlet on. Each of the gas channels has a corresponding fitting for its alternating opening and close on. By means of at least two pulsed gas streams, the exhaust gas inflow can be imitate a loader more realistically than with just one pulsed one Gas stream, since each gas stream at least one gas stream of a cylinder or a flood of one or more cylinders can. in principle Each valve can be controlled individually.

to Generation complementary pulsed gas streams In particular, a pulse generating unit is preferred in which the respective gas channels to each other time-delayed openable and are lockable, in particular alternately.

Then, to obtain a simple structure, a pulse generating unit is preferable in which the at least two gas passages can be opened and closed by means of a common rotary valve. The opening and closing cycles are then phase-locked to each other. Alternatively, the closing body of the valves by at least one power transmission element can be driven together, z. B. by means of a common shaft, which z. B. is articulated to different ball valves.

It is for a particularly simple construction a pulse generating unit preferred in which the common rotary valve a closing body, with in terms of having its axis of rotation angularly offset through holes. In the case of two fluidically separated gas channels, a closing body is preferred, in which the through holes are perpendicular to each other or offset by 90 ° are. With three fluidically separated gas ducts, three become 60 ° apart angular offset through holes preferred, at four fluidly separate gas channels become four at 45 ° to each other angular offset through holes preferred, and so on.

It is preferred if the closure body is a cylindrical closure body, However, it may also have a different shape, for. B. spherical.

to flow stabilization a pulse generating unit is preferred which has a recirculating air channel, the at least one fitting bypasses and preferably in the behind the turbocharger sitting exhaust pipe leads. The flow cross section the circulating air channel is preferably controllable.

It Furthermore, a pulse generating unit is preferred in which the valves a common calming chamber in the form of a gas storage volume aerodynamically upstream to ensure a constant mass flow and to protect the combustion chamber from unwanted pulsations.

Of the Test bench, in particular an exhaust gas turbocharger test stand, has at least one, in particular as described above, pulse generating unit.

It becomes a test bench preferred in which of the stationary combustion chamber and the pulse generating unit at least one storage volume is fluidically interposed, the one constant mass flow at one of the pulse generating unit fluidically upstream combustion chamber allows.

It also becomes a test bench preferred, the a motor, in particular electric motor, for driving of the final body having.

Of the Engine is preferably a variable speed motor.

The speed of the roller depends on the number of rotating holes, the engine speed to be simulated and the number of cylinders, ie that in a 4-cylinder engine with four exhaust strokes per 720 ° crank angle and a pulse generator unit with two offset by 90 ° holes (corresponding four exhaust strokes per 360 ° roll angle), the roller should rotate at half the motor speed in order to map it correctly. The most interesting speed range in the present case is 500 <N _roll <1250 [1 / min] ("Low End Torque" (LET) range). In principle, however, the entire speed range of the engine to be examined of interest.

One Part of the analysis of the measured data lies in the determination of the mass flow profile the pulsed flow over the Exhaust turbine. Because a direct measurement of the time-varying Mass flow path not possible is, the mass flow characteristics become calculated. As input variables for this are previously angular static on both sides of the pulse generating unit measured pressure gradients over the Pulser generating unit used. The calculation of the mass flow curve then takes place by means of a gas simulation simulating flow simulation program, which simulates the pulses of the pulse generating unit.

to Determination of the mass flow curve, a test stand is preferred, which at least a first gas pressure sensor (X) in front of the fitting and at least one second gas pressure sensor behind the valve, wherein the at least a first gas pressure sensor and the at least one second gas pressure sensor by means of the armature alternately fluidly connectable and separable are. The gas pressure sensor may be part of the pulse generation unit or this before and / or be downstream. By means of at least a pressure measurement before (upstream) and behind (downstream) the Valve can be calculated from the mass flow curve. to redundant measurement can several pressure sensors in the same gas channel before and / or behind the Faucet be present. It can Pressure sensors in one or more separate gas channels available which are passed through the pulse generating unit. So like the equipment be sufficient only a gas channel with pressure sensors.

The Method for operating such a test bench has at least the following steps: measuring a pressure gradient by means of at least a first gas pressure sensor; Measuring a pressure curve by means of the at least one second gas pressure sensor and calculating a Mass flow curve from the measured pressure curves.

In the following figures, the invention described in more detail schematically with reference to an embodiment. It can be provided with the same reference numerals for better clarity identical or equivalent elements.

1 shows a schematic diagram of an exhaust gas turbocharger test bench;

2 shows a sectional side view of a drawing of a pulse generating unit.

1 shows an exhaust gas turbocharger test stand 1 , which first a compressor 2 for compressing an incoming gas stream to which a stationary combustion chamber 3 connects with upstream heating. From the combustion chamber 3 exiting exhaust gases are in an exhaust gas storage 4 (Sedation storage) of a size between 25 liters and 100 liters, which has a substantially constant mass flow from the combustion chamber 3 ensures exiting exhaust gases. From the exhaust gas storage 4 For example, the exhaust gases are treated as substantially unpulsed (with respect to their mass flow or pressure not rapidly changing) exhaust gas flows via two separate supply channels 5a to a pulse generating unit 6 continued. In the pulse generation unit 6 The substantially unpumped exhaust gas streams are further fluidly separated into pulsed exhaust gas streams and also separated into drainage channels 5b output. For this purpose, the pulse generating unit 6 fluidically separated exhaust gas channels 7 on the input side with a respective one of the supply channels 5a and on the output side with one of the respective discharge channels 5b are connected. Each of the exhaust channels 7 is by means of a fitting 8th controlled optionally openable and lockable. At the downstream outlet side of each fitting 8th the pressure is dependent on a position of the valve 8th , With the valve closed 8th the exhaust pressure drops behind the valve 8th up to a maximum of a depressurized state. At the following opening of the valve 8th the exhaust pressure rises again, and so on. This allows a pressure-pulsed exhaust gas flow at the outlet side of the valve 8th produce. Among other things, the pulse shape depends on the opening frequency, the flow diameter and the type of valve 8th from. The two shown fittings 8th are set to alternately open and close to each other so that respective pulsed exhaust gas flows with mutually complementary shape, ie, that a high pressure region of a pulsed exhaust gas flow substantially coincides with a low pressure region of the other pulsed exhaust gas flow. The exhaust gas streams may represent, for example, the two floods of an internal combustion engine. The fittings 8th are here as a single double rotary valve with a common cylindrical end body 15 executed, in the mutually perpendicular gas passage holes 16 . 17 are introduced and by means of a drive motor 20 is turned.

In the sketch is also an exhaust gas turbocharger 9 as in the test 1 used inserted. The turbocharger 9 is on the input side with the two gas outlets of the pulse generation unit 6 connected, where the pulsed exhaust gas streams are output. On the output side of the exhaust gas turbocharger 9 the exhaust gases are through an exhaust 10 drained.

Optionally, between the exhaust gas storage 4 and the exhaust 10 as a direct fluidic connection a recirculating air duct 11 be present, drawn here by dashed lines, which consequently the fittings 8th bypasses. By means of the circulating air channel 11 can be a vibration or pulse damping for the stationary combustion chamber 3 be achieved.

The pulse generation unit 6 makes it possible at the turbocharger test bench 1 real flow conditions of the loader 9 to simulate. This measuring methodology allows very detailed evaluations already in early stages of development. The so-called "Ladermatching" can be extended to the dynamic loading (shock charging), which can be done so far in the experiment only on the engine test bench. In addition, the interactions of the manifold / flange / turbine chain and internal leaks in the individual components can be evaluated and analyzed. Due to the cost-effective investigations and the very early information gain there is a great potential for a reduction of development costs. At the same time, knowledge can be gained by systematic measurements of turbine loading, which can be used as direct input quantities in, for. B. one- or three-dimensional simulation programs can serve. Such reliable calculation models can significantly improve the reliability of design, which in turn opens up potential for reducing development costs.

In particular, here are for determining the mass flow profile of the exhaust gas in one of the supply ducts 5a in front of the fitting 8th and in an associated one of the drainage channels 5b behind the faucet 8th in each case a first pressure sensor 18a or a second pressure sensor 18b introduced so that the first gas pressure sensor 18a and the second gas pressure sensor 18b by means of the fitting 8th alternately fluidly connectable and separable. The pressure curves at the sensors 18a . 18b are recorded and calculated from the mass flow curve. The pressure sensors 18a . 18b have here cooled pressure measuring crystals. The resulting mass flow profile can be used, for example, to adjust the simulation parameters. From the mass flow over the pulse generating unit 6 also results in the mass flow over the turbocharger.

2 shows a possible embodiment of the pulse generating unit 6 in greater accuracy.

The pulse generation unit 6 points here in her case 12 on the upper side two exhaust gas inlets 13 on, to the outside of each a supply channel 5a same inside diameter of the exhaust gas reservoir (calming memory) 4 out 1 is flanged. The exhaust gas inlets 13 lie exactly opposite to the housing 12 two exhaust outlets 14 across from. For example, laterally merged discharge channels in the form of an exhaust manifold, which leads to a turbine of the turbocharger, can be flanged to the exhaust gas outlets. The inner diameter corresponds in practice to the inner diameter of the associated exhaust manifolds, for example, 15 mm to 75 mm, but can also be below or far above, z. B. for marine diesel.

Fluidic and physical between the exhaust inlets 13 and the exhaust outlets 14 is in the case 12 a cylindrical closing body (roller) 15 freely rotatably mounted present, which is part of a rotary valve. In the roller 15 are two through holes 16 . 17 introduced so that they are angularly offset by 90 ° with respect to a longitudinal axis L of the roller, which also corresponds to the axis of rotation, so perpendicular to each other. Their diameters correspond to those of the supply lines and discharges.

In the illustration shown is the roller 15 in a rotational position, in which the left exhaust duct 7 shut off and the right exhaust duct 7 is fully open. Since the diameters (corresponding to the flow cross sections) of the supply channel 5a , the elements 13 . 14 . 17 and preferably the discharge channel are the same, occur in the right, fully opened exhaust passage 7 hardly any flow losses. On the left, the closed rotary valve 8th following exhaust outlet 14 A lower exhaust gas volume flow or exhaust gas pressure has been set, while a high exhaust gas volume flow or exhaust gas pressure is present on the right. With a rotation of the roller 15 closes the right rotary valve 8th , while the left opens with a corresponding change in the exhaust gas flow or exhaust pressure. As a result, the two exhaust channels 7 or the two gas inlets 13 and gas outlets 14 alternately openable and closable.

For rotation of the roller 15 , in particular in only one direction, this is with an end face with a drive shaft 19 connected laterally through the housing 12 to be led. The drive shaft 19 is connected to the speed-controllable drive motor, not shown here. By using only one roller 15 for phase-locked opening of both exhaust ducts 7 instead of the - basically possible - use of separate valves is a particularly inexpensive, fast switching and fail-safe possibility for generating pulsed gas flows possible. A lower design possibility in the formation of the pulses is due to the usually also phase-locked combustion chamber activation in an internal combustion engine little importance.

specially can Turbines on the test bench with pulsed flow be charged. Variations of essential flow parameters, like pulse height, Pulse duration and frequency can relatively easy by change the roll geometry (number of holes, diameter of the holes and outside diameter the roller) or by changing the Roller speed can be mapped.

Of course it is the present invention is not limited to the embodiment shown limited.

So can generally turbocharger for turbo charged internal combustion engines are tested, for. B. for cars, trucks, Special vehicles and even ships (marine diesel).

1

Turbocharger Test Bench

2

compressor

3

stationary combustion chamber

4

exhaust memory

5a

supply channel

5b

Waterway

6

Pulse generating unit

7

exhaust duct

8th

Valve

9

turbocharger

10

Exhaust

11

return air duct

12

casing

13

exhaust inlet

14

exhaust outlet

15

roller

16

Through Hole

17

Through Hole

18

Gas pressure sensor

19

drive shaft

20

drive motor

Claims (12)

Pulse generating unit ( 6 ) for generating a pulsed gas stream from a substantially unpulsed gas stream, wherein the pulse generating unit ( 6 ) at least one fitting ( 8th ) for alternately opening and closing mindes least one gas channel ( 7 ) between at least one gas inlet ( 13 ) for the admission of the unpulsed gas stream and at least one gas outlet ( 14 ) for discharging the pulsed gas flow. Pulse generating unit ( 6 ) according to claim 1, in which the fitting ( 8th ) a rotary valve with a freely rotatable closing body ( 15 ) having. Pulse generating unit ( 6 ) according to claim 2, comprising at least two fluidically separated gas channels ( 7 ), which alternately to each other by means of at least one rotary valve ( 15 ) can be opened and closed. Pulse generating unit ( 6 ) according to claim 2 and 3, wherein the at least two gas channels ( 7 ) by means of a common rotary valve ( 15 ) can be opened and closed. Pulse generating unit ( 6 ) according to claim 4, wherein the common rotary valve has a closing body ( 15 ), in particular cylindrical closing body ( 15 ), with respect to its axis of rotation (L) angularly offset, in particular perpendicular to each other, through holes ( 16 . 17 ) having. Pulse generating unit ( 6 ) according to one of the preceding claims, which has a recirculating air channel ( 11 ), the at least one fitting ( 8th ) bypasses. Test bench ( 1 ), in particular for exhaust gas turbochargers ( 9 ), comprising at least one pulse generation unit ( 6 ) according to any one of the preceding claims. Test bench ( 1 ) according to claim 7, comprising at least one of the pulse generating unit ( 6 ) is fluidly connected upstream. Test bench ( 1 ) according to claim 8, wherein the stationary combustion chamber ( 3 ) and the pulse generating unit ( 6 ) at least one storage volume ( 4 ) is fluidically interposed. Test bench ( 1 ) according to one of claims 7 to 9, comprising a motor ( 20 ) for driving the closing body ( 15 ), in particular variable-speed engine ( 20 ). Test bench ( 1 ) according to one of claims 7 to 10, comprising at least one first gas pressure sensor (X) in front of the fitting ( 8th ) and at least one second gas pressure sensor (Y) behind the valve ( 8th ), wherein the at least one first gas pressure sensor (X) and the at least one second gas pressure sensor (Y) by means of the valve ( 8th ) are alternately fluidically connectable and separable. Method for operating a test stand according to claim 11, which at least the following steps: - Measure up a pressure curve by means of the at least one first gas pressure sensor (X); - Measure up a pressure curve by means of the at least one second gas pressure sensor (Y); - To calculate a mass flow profile from the measured pressure curves.