WO2009138617A2

WO2009138617A2 - Test device and method for automobile

Info

Publication number: WO2009138617A2
Application number: PCT/FR2009/050692
Authority: WO
Inventors: François Roussel
Original assignee: Renault S.A.S.
Priority date: 2008-04-16
Filing date: 2009-04-15
Publication date: 2009-11-19
Also published as: WO2009138617A3; FR2930338B1; FR2930338A1; EP2265921A2

Abstract

The invention relates to a test device for the propulsion unit of an automobile, including a casing (2) having a space corresponding to that of the propulsion unit and intended for receiving a propulsion unit (1), including an air inlet (4) and an air outlet (5), characterised in that the air inlet (4) includes an upper channel (9) capable of generating a first air flow reproducing an air flow under the bonnet of an automobile, and a lower channel (10) capable of generating a second air flow, the second air flow being substantially faster than the first air flow, in order to reproduce the air flow that flows under the automobile.

Description

DEVICE AND TEST METHOD FOR MOTOR VEHICLE

The invention relates to a test device for a powertrain (GMP) of a motor vehicle. It also relates to a test method of a powertrain (GMP) of a motor vehicle.

There exists in the state of the art a solution, as described in the document FR2879742, which is based on the test of a powertrain via a motor vehicle disposed in its entirety in a test chamber cooled to the desired temperature. Such a solution is illustrated in FIG. 6, which shows a motor vehicle 20 in a test bench, subjected to a flow of air generated by a ventilation system 21 and transmitted by a fan 22. Towards the rear of the vehicle 20, a system 23 draws exhaust gas and a device 24 draws ambient air to amplify the generated airflow within the volume of the entire room. Different measuring devices 26 are present in the same volume 25. Such a solution has many disadvantages. First, it requires the use of an entire vehicle while only testing its engine. Then, it is necessary to cool a large volume of air since the test chamber has a large volume 25. Finally, the measuring devices 26 used do not always support the cooled temperature for carrying out the test, need to be close to or measuring points for precision concerns and it is therefore necessary to heat them individually, which complicates the device and increases its overall energy consumption. Finally, the heaviness of this solution is very far from optimal.

To overcome these drawbacks, the solution described in patent EP0857959 proposes to test the powertrain in isolation by placing it in a closed chamber 2. However, this solution has the disadvantage of not reproducing the air flow it receives in a motor vehicle during its movement. The tests thus carried out are in conditions far removed from reality and their results are therefore unreliable. The object of the invention is a device and a test method of a powertrain of a motor vehicle which improve the existing solutions mentioned above.

More particularly, the invention firstly relates to a simple device that does not require a large volume.

A second object of the invention is a device that best reproduces the flow of air received by a powertrain within a motor vehicle during its movement.

A third object of the invention is a test device offering good conditions for the durable and reliable use of measuring devices while allowing a proximity of the apparatus with respect to the capture points.

For this purpose, the invention is based on a test device for a powertrain of a motor vehicle, comprising a volume box corresponding to that of a powertrain and intended to receive a powertrain, comprising an air inlet and an outlet of air, characterized in that the air inlet comprises an upper channel capable of generating a first air flow reproducing an air flow under the hood of a motor vehicle, and a lower channel capable of generating a second air flow, the second air flow is significantly faster than the first air flow, to reproduce the flow of air flowing under a motor vehicle.

The upper channel may be able to generate a first low-speed air flow corresponding to approximately 15% of the simulated speed of a motor vehicle, and the lower channel may be able to generate a second air flow at high speed corresponding to about 60% average of the simulated speed of a motor vehicle. The upper channel may include an element simulating a motor vehicle radiator and the second lower channel may include a "convergent" type geometry to accelerate the airflow.

This device may comprise a single air intake channel, which separates on the one hand the upper air flow and on the other hand the lower air flow at the air inlet of the box .

The box may have a closed restricted volume capable of surrounding a powertrain to be tested so that the upper channel is at the level of the upper components of a powertrain which are usually located under a motor vehicle hood and so that the channel lower is the lower components of the powertrain that are usually located at the bottom surface of a motor vehicle.

The output of the device may be adapted to receive the exhaust of a powertrain, and it may comprise a suction device for accelerating the air flow at the outlet of the device, the outlet having a baffle geometry in order to accelerate the airflow.

The powertrain test device may include at least one meter out of the box.

The invention also relates to a method for testing a power unit of a motor vehicle, comprising a step of positioning the power unit in a closed box of restricted volume around the power unit, characterized in that it comprises the two stages following simultaneous: -send a higher air flow at low speed at an upper part of the box, able to simulate a flow of air under the hood of a motor vehicle, sending a lower air flow at a higher speed to a lower part of the box, in order to simulate the flow of air flowing under a motor vehicle.

The lower airflow can be at least seven times greater than the upper airflow. The speed of the lower airflow can be about 300% higher than that of the higher airflow.

The two lower and upper flows can be obtained from the same stream of air at a constant low speed, less than 2 meters / second.

These objects, features and advantages of the present invention will be set forth in detail in the following description of a particular embodiment made in a non-limiting manner in relation to the appended figures among which:

FIG. 1 represents a partial perspective view of a test device for a power unit of a motor vehicle according to one embodiment of the invention; FIG. 2 represents another perspective view of a test device for a power unit of a motor vehicle according to the embodiment of the invention; FIG. 3 represents a sectional view of a detail of the test device for a power unit of a motor vehicle according to the embodiment of the invention; FIG. 4 represents a perspective view of this detail of the test device for a power unit of a motor vehicle according to the embodiment of the invention; FIG. 5 represents a sectional view of another detail of the test device for a power unit of a motor vehicle according to the embodiment of the invention; FIG. 6 represents a test device for a power unit of a motor vehicle according to a solution of the state of the art. According to the invention, the power unit 1 to be tested of a motor vehicle is disposed in a box or enclosure 2 of corresponding volume as shown in Figure 1. On a first side of this box is arranged an air intake 3. This air is directed to an inlet 4 of the box 2 at which is placed the part of the powertrain 1 for positioning in the front part under the hood of a motor vehicle. On the opposite face of the casing 2 is arranged an outlet 5 through which the air flow and which corresponds to the exhaust 6 of the power unit 1. All these elements rest on a frame 7.

FIG. 2 illustrates a more general view of the test environment for a powertrain 1. The closed enclosure 2 is surrounded by numerous measuring devices 8. This configuration has the advantage that only the restricted volume of the enclosure 2 requires cooling to put the power train 1 in its test conditions. The volume of this zone is therefore advantageously optimized, designed to best match the volume of the powertrain. On the other hand, the entire environment, close to the powertrain under test, comprising the measuring devices 8 and distributed around this enclosure 2 can remain at a normal, warmer temperature, allowing the optimal operation of the measuring devices.

The device comprises a supply of the box 2 by a flow of air at constant temperature. According to an essential element of the invention, the device reproduces a flow of air that is as close as possible to the flow that actually applies to the powertrain when it is within a moving motor vehicle. For this, the device allows in particular to artificially reproduce the flow of air as it exists under the hood of a motor vehicle combined with a different air flow that exists under the motor vehicle. For this, the air inlet 3 is obtained by a channel whose geometry can create, from a single air flow, two flows with different characteristics. In its final part, the air inlet channel is separated into two high 9 and low 10 parts. In the upper part 9, an element 11 simulates the effect of a motor vehicle radiator by representing a pressure drop. airflow, which decreases its speed. On the contrary, the lower stream is accelerated using a "convergent" type part. Then, these two air flows are directed in such a way in the box that they arrive on the powertrain 1 in a manner similar to the arrival of respectively flows under the hood of the motor vehicle and under the motor vehicle in a configuration real. Then, the inner shapes of the box 2 are designed to reproduce the air circulation under hood during the movement of the vehicle, and contain the powertrain in the areas corresponding to the air flow that it undergoes during such a displacement. For this, the volume of the box can be separated by horizontal planes in several parts: the lowest part is intended to understand the lowest components of the powertrain, arranged towards the bottom of a vehicle, which undergo thus the high-speed air flows, the central and upper parts of the chamber 2 receive the higher air flow at low speed. Towards the outlet 5 of the device, the two air flows meet around the exhaust 6 at a speed accelerated by baffles, in a restricted volume outlet channel. As this airflow undergoes significant pressure drops in its path in the chamber 2, an air suction device is added at the outlet 5 in order to maintain a suitable flow of air in the second part of the device.

This device allows the implementation of a test method based on a single inflow of air entering at a constant low speed, for example less than 2 meters / second, which allows a good control of the parameters of flow, temperature and hygrometry of the air flow. Then, the geometry of the device is chosen to obtain a sharing of the order of 80% of the incoming air flow oriented in the upper part 9 of the inlet channel 4 in the chamber 2, and 20% oriented in its lower part 10. The air flow of the upper part 9 reaches a low speed of the order of 15% of the speed of the vehicle imposed by the test, while the speed is of the order of 60% of this speed of the vehicle in the lower part 10. Finally, the output air flow 5 of the device also has a value close to 60% of this speed of the motor vehicle. The method according to the invention therefore implements the following two essential steps:

sending a first upper air stream at low speed at an upper part of the chamber 2, able to simulate an air flow under the hood of a motor vehicle, sending a second lower air flow at higher speed at a lower portion of the chamber 2, to simulate the flow of air flowing under a motor vehicle.

This solution thus makes it possible to best simulate the natural or forced ventilation existing in the different main areas of a motor vehicle. Indeed, the two air streams obtained have very different characteristics and apply to particular and distinct elements of the powertrain, conditioning the thermal of the entire powertrain. The first upper airflow that passes through the area under the hood of the vehicle at a low speed between 10 and 20% of the vehicle speed, applies to some heat exchangers, such as the radiator, the charge air cooler , Exhaust Gas Recirculation (EGR) or exhaust manifold, turbocharger. The second, faster air flow, corresponding to the flow of air under the vehicle, which slides on a carpet of air at a speed close to that of the vehicle and which reaches about 60% of the speed of the vehicle at its level. contact with certain lower elements of the vehicle, applies to other components of the powertrain such as the catalyst, the particulate filter. The distinction of these two very different air flows and their distribution in the test device at the relevant components of the powertrain makes it possible to effectively and simply simulate the effects of the airflow that actually applies when moving. of a motor vehicle. This concept of the invention can be implemented by other geometries of the device, which is not limited to the embodiment described. In addition, several different speeds can be implemented, since they depend in fact on the speed of the motor vehicle which can be variable. The essential element is that the speed of the lower flow is significantly greater than the speed of the upper airflow. Any solution in which the device is subjected to a lower velocity air flow at least seven times higher than that of another upper air flow may enter into the concept of the invention.

The test stand has been illustrated with a constant velocity airflow. However, the device may allow to use a variable air flow to simulate different speeds of a motor vehicle, using a bypass valve calibrated according to the speed of the vehicle in open automation.

The device of the invention therefore allows an effective application to a motor vehicle engine test bench, as has been described. It is particularly relevant for all tests whose results are sensitive to ventilation phenomena under the hood, such as those concerning the engine or the gearbox. Similarly, it is also relevant for any analysis of anti-pollution devices (EGR, particulate filter, for example), implementing elements sensitive to thermal characteristics, directly related to their mode of ventilation, such as the turbocharger, the device EGR, the particulate filter ... It is naturally also useful for all aerothermal type tests.

Claims

Motor vehicle powertrain test device, comprising a box (2) of volume corresponding to that of a power unit and intended to receive a power unit (1), comprising an air intake (4) and a air outlet (5), characterized in that the air inlet (4) comprises an upper channel (9) adapted to generate a first air flow reproducing a flow of air under the hood of a vehicle automobile, and a lower channel (10) capable of generating a second air flow, this second air flow being significantly faster than the first air flow, in order to reproduce the flow of air flowing under a motor vehicle .

2. Test device for powertrain of a motor vehicle according to claim 1, characterized in that the upper channel (9) is adapted to generate a first low velocity air flow corresponding to about 15% average of the simulated speed of a motor vehicle, and in that the lower channel (10) is adapted to generate a second high-speed air flow corresponding to about 60% average of the simulated speed of a motor vehicle.

Motor vehicle powertrain test device according to claim 2, characterized in that the upper channel (9) comprises an element (11) simulating a motor vehicle radiator and in that the second lower channel (10) comprises a "convergent" geometry to accelerate the flow of air.

4. Test device for powertrain of a motor vehicle according to claim 3, characterized in that it comprises a single channel (3) of air intake, which separates on the one hand the upper airflow (9) and on the other hand the lower air flow (10) at the air inlet (4) of the box (2).

5. Test device for powertrain of a motor vehicle according to one of the preceding claims, characterized in that the box (2) has a closed restricted volume capable of surrounding a powertrain (1) to be tested so that the upper channel (9) is located at the upper components of a power train (1) which are usually located under a hood of a motor vehicle and so that the lower channel (10) is at the lower components of the power train (1). ) which are usually located at the lower surface of a motor vehicle.

Motor vehicle powertrain test device according to one of the preceding claims, characterized in that the output (5) of the device is adapted to receive the exhaust (6) of a power unit (1), in it comprises a suction device for accelerating the flow of air at the outlet of the device and in that the outlet (5) has a baffle-type geometry to accelerate the flow of air.

7. Test device for powertrain of a motor vehicle according to one of the preceding claims, characterized in that it comprises at least one measuring device out of the box (2).

8. A method for testing a motor vehicle power unit, comprising a step of positioning the power unit (1) in a closed box (2) of restricted volume around the power unit (1), characterized in that it includes the following two simultaneous steps:

sending a higher air flow at low speed at an upper part of the box (2), able to simulate an air flow under the hood of a motor vehicle, sending a flow of air air lower speed at a lower portion of the box (2), to simulate the flow of air flowing under a motor vehicle.

9. A method of testing a powertrain of a motor vehicle according to the preceding claim, characterized in that the lower air flow is at least seven times greater than the upper air flow.

10. A method of testing a motor vehicle powertrain according to one of claims 8 to 9, characterized in that the two lower and upper flows are obtained from the same constant low speed air flow, less than 2 meters / second.