Method for monitoring a short-circuit solenoid valve in an electric machine cooling circuit

Abstract

The invention relates to a method for monitoring a short-circuit solenoid valve in the cooling circuit of an electrical machine (1), the cooling circuit comprising a heat exchanger (3) and a short-circuit solenoid valve (5), wherein, following activation of the short-circuit solenoid valve, the method comprises the steps of: a) Incrementing a counter value; b) If the counter value is greater than a first predetermined threshold value, controlling the short-circuit solenoid valve to a first state, where a heat transfer fluid from the cooling circuit is directed to the heat exchanger. (Fig. 1)

Description

Title of the invention: Method for monitoring a short-circuit solenoid valve in an electric machine cooling circuit. Technical field of the invention

[0001] The invention relates to the field of electrical machines for motor vehicles. In particular, the invention concerns a method for monitoring a short-circuit solenoid valve in an electric machine cooling circuit. Prior art

[0002] Currently, in order to allow for faster heating during the start-up of an electric machine in a powertrain for a motor vehicle, a bypass solenoid valve is installed within the electric machine's cooling circuit. This valve bypasses a heat exchanger in the cooling circuit during the start-up phase. This allows the electric machine to heat up more quickly, reducing the pressure losses of the electric machine during startup. If the bypass solenoid valve fails in the bypass position, the temperature of the electric machine, with the heat exchanger then bypassed, increases by 1°C per second for motor torques exceeding 300 Nm. Consequently, this temperature reaches a critical temperature within a few seconds of the electric machine's operation, beyond which the electric machine presents a high risk of failure. Description of the invention

[0003] The invention aims to remedy all or part of the disadvantages of the prior art by proposing in particular a solution to prevent a high risk of failure of such a short-circuit solenoid valve in a cooling circuit of an electric traction machine.

[0004] To this end, according to a first aspect of the invention, a method for monitoring a short-circuit solenoid valve in the cooling circuit of an electrical machine is proposed, the cooling circuit comprising a heat exchanger and a short-circuit solenoid valve, wherein, following activation of the short-circuit solenoid valve, the method comprises the following steps: a. Incrementing the value of a counter; b. If the value of the meter is greater than a first predetermined threshold value, the short-circuit solenoid valve is controlled in a first state, where a heat transfer fluid from the cooling circuit is directed to the heat exchanger.

[0005] According to one embodiment, during step b), the process then performs an inhibition of any subsequent short-circuit solenoid valve control.

[0006] According to one embodiment, during step b), the process then emits a first fault code and commands a service indicator light to be switched on.

[0007] According to one embodiment, following step b), a replacement of the short-circuit solenoid valve and a reset to zero of the counter value are required.

[0008] According to one embodiment, prior to step b), the process includes a step a') of: if the value of the counter is greater than a second threshold value, emission of a second fault code.

[0009] According to one embodiment, following step a'), a check for wear of the short-circuit solenoid valve is requested.

[0010] According to one embodiment, during step a), an increment value of the counter value is different depending on whether the short-circuit solenoid valve goes from the first state to a second stage, where a heat transfer fluid from the cooling circuit is directed in a bypass line to the electric machine, or from the second state to the first state.

[0011] According to another aspect of the invention, a powertrain is provided comprising an electric traction machine and a cooling circuit for the electric machine, the cooling circuit comprising a short-circuit solenoid valve and a heat exchanger, in which the powertrain further comprises a computer arranged to implement a monitoring method having at least one of the preceding technical characteristics.

[0012] According to yet another aspect of the invention, a motor vehicle is provided comprising a powertrain having one of the preceding technical characteristics. Brief description of the figures

[0013] Other features and advantages of the invention will become apparent from the following description, with reference to the attached figure, which illustrates: • [Fig.1]: is a schematic view of an electrical machine including a cooling circuit.

[0014] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of a method of implementation

[0015] With reference to [Fig.1], we will briefly describe a powertrain 10 in which a method for monitoring a short-circuit solenoid valve according to the invention.

[0016] The powertrain 10 is intended to equip a motor vehicle. The powertrain 10 includes an electric traction machine 1 known per se. Furthermore, the powertrain 10 includes a cooling circuit 15, 5, 5, 3, 3, 1, 51 for the electric machine 1.

[0017] The cooling circuit includes a heat exchanger 3, for example, an oil / water type heat exchanger. Within the electric machine 1, a heat transfer fluid, such as oil, is used to cool a stator and a rotor of the latter. At the outlet of the electric machine 1, the hot heat transfer fluid flows to the heat exchanger 3 within a supply line 15, 51. Then, the heat transfer fluid cooled within the heat exchanger 3 returns to the electric machine 1 via a return line 31.

[0018] The cooling circuit further includes a short-circuit solenoid valve 5 provided on the supply line 15,51, dividing the supply line 15,51 into an upstream line 15 between the electric machine 1 and the short-circuit solenoid valve 5 and a downstream line 51 between the short-circuit solenoid valve 5 and the heat exchanger 3.

[0019] In addition, the cooling circuit includes a bypass line 51 between the short-circuit solenoid valve 5 and the electric machine 1. The short-circuit solenoid valve 5 is, here, a three-way solenoid valve.

[0020] In operation, the short-circuit solenoid valve 5 can take the following states. In a first state El, the short-circuit solenoid valve 5 directs the heat transfer fluid towards the heat exchanger 3 to cool the heat transfer fluid from the electric machine 1 and thus cool parts of the electric machine 1.

[0021] In a second state E2, the short-circuit solenoid valve 5 prevents the heat transfer fluid from passing through the heat exchanger 3 by directing said heat transfer fluid into the bypass line 51. This allows the heat transfer fluid from the electric machine 1 to rapidly increase in temperature, thus optimizing the efficiency of the electric machine 1 when it is cold (start-up phase of the electric machine 1). This rapid temperature increase of the heat transfer fluid reduces pressure losses when the fluid is too cold. This allows for a rapid reduction of pressure losses in the cold electric machine 1, resulting in increased efficiency, reduced energy consumption, and therefore increased operating time.

[0022] However, the drawback is that if this short-circuit solenoid valve 5 gets stuck in state E2, the heat transfer fluid allowing cooling of the stator and rotor of the electric machine 1 is no longer cooled within the heat exchanger 3 and therefore there is a rapid risk to the integrity of the stator and rotor of the electric machine 1 if a temperature of the heat transfer fluid exceeds a predetermined critical temperature.

[0023] In order to prevent this situation, the powertrain 10 includes a computer 7 arranged to implement a method for monitoring a short-circuit solenoid valve according to the invention which we will now describe.

[0024] The short-circuit solenoid valve 5 is controlled by the computer 7 of the powertrain 10, i.e. the short-circuit solenoid valve 5 changes from state El to state E2 and from state E2 to state El, on command of the COMPUTER 7 of the powertrain 10. These changes of state are counted by the method of monitoring a short-circuit solenoid valve according to the invention.

[0025] Therefore, in a first step, the method for monitoring a short-circuit solenoid valve according to the invention increments a counter Comp at each change of state requested by the computer 7 of the powertrain 10, that is to say when the computer 7 commands the short-circuit solenoid valve 5 to be in state El, the method for monitoring a short-circuit solenoid valve according to the invention records that the short-circuit solenoid valve 5 is in state El, but when the computer 7 of the powertrain 10 commands the short-circuit solenoid valve 5 to go to state E2, the method for monitoring a short-circuit solenoid valve according to the invention detects that the setpoint is no longer similar to that previously memorized and therefore the method for monitoring a short-circuit solenoid valve according to the invention increments the counter Comp by 1.

[0026] The Comp counter is initialized at the factory to the value 0 and the calculator 7 can only reset the Comp counter to 0 when the short-circuit solenoid valve 5 is changed.

[0027] Following each increment of the Comp counter, the method for monitoring a short-circuit solenoid valve according to the invention, in a second step, compares the value of the Comp counter with a second threshold value S2, which is here a simple alert threshold. This second threshold value S2 is calibrated during the development of the method for monitoring a short-circuit solenoid valve according to the invention. For example, the second threshold value S2 is calibrated at 8,000 activations.

[0028] When the value of the counter Comp becomes greater than or equal to the second threshold value S2, the monitoring method for a short-circuit solenoid valve according to the invention issues a second fault code. When a service department finds this second fault code during a vehicle inspection, they are asked to check the operation and condition of the short-circuit solenoid valve 5. This remains invisible to a vehicle user; that is, there is no "service" light, no dashboard warning light, and no messages. Reaching this second threshold value S2 is completely transparent to the user.

[0029] Next, the method for monitoring a short-circuit solenoid valve according to the invention compares the value of the Comp counter with a first threshold value SI, greater than the second threshold value S2, which is, in this case, a blocking threshold for the short-circuit solenoid valve 5. This first threshold value SI can be calibrated during the development of the method for monitoring a short-circuit solenoid valve according to the invention. For example, the first threshold value SI is calibrated at 10,000 activations.

[0030] When the value of the Comp counter becomes greater than or equal to the first threshold value SI, the method of monitoring a short-circuit solenoid valve according to the invention, in a subsequent step, performs a reconfiguration which takes place in two stages.

[0031] Initially, the method for monitoring a short-circuit solenoid valve according to the invention inhibits the operation of the short-circuit solenoid valve 5; that is, the method for monitoring a short-circuit solenoid valve according to the invention commands the short-circuit solenoid valve 5 to the E1 state position and blocks or prevents any command of the short-circuit solenoid valve 5 from returning to the E2 state position. The aim is that, after the first threshold value SI, the short-circuit solenoid valve 5 always directs the heat transfer fluid towards the heat exchanger 3 of the cooling circuit of the electrical machine 1 in order to cool the heat transfer fluid from the electrical machine 1 and thus cool the parts of said electrical machine 1.In other words, a bypass function of the heat transfer fluid is no longer possible; the heat transfer fluid is forced to always pass through the heat exchanger 3 of the cooling circuit of the traction electric machine 1.

[0032] In a second step, the method for monitoring a short-circuit solenoid valve according to the invention issues a first fault code and triggers a service indicator light on the vehicle's dashboard, to instruct the user to go to the service center for verification. When the service center finds this first fault code, it is instructed to replace the short-circuit solenoid valve 5 and reset the value of the Comp counter to 0, once the short-circuit solenoid valve 5 has been replaced.

[0033] It should be noted that the value of the Comp counter is accessible at any time to the after-sales service via a query in the after-sales service diagnostic tool, so that the latter can have visibility on the number of occurrences of the activation of the short-circuit solenoid valve 5.

[0034] In one embodiment, the method for monitoring a short-circuit solenoid valve according to the invention performs on the counter Comp a different increment between a transition from state El to state E2 and a transition from state E2 to state El, and this, depending on a difficulty in transitioning from one state to the other for the short-circuit solenoid valve 5.

[0035] It appears that the implementation of the method for monitoring a short-circuit solenoid valve according to the invention just described has the advantage of ensuring Monitoring the activation of the short-circuit solenoid valve 5 prevents damage to the traction motor 1 in case of a short-circuit solenoid valve 5 failure due to wear and tear. Therefore, this monitoring system is beneficial to the user, ensuring the integrity of the traction motor 1. It also prevents malfunctions of the short-circuit solenoid valve 5 caused by excessive actuation, and assists after-sales service in diagnosing the short-circuit solenoid valve 5.

[0036] Naturally, the invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from the scope of the invention.

[0037] It is emphasized that all features, as they are apparent to a person skilled in the art from the present description, drawings and attached claims, even if in practice they have only been described in relation to other specific features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or meaningless.

Claims

Demands

1. A method for monitoring a short-circuit solenoid valve of a cooling circuit of an electrical machine (1), the cooling circuit comprising a heat exchanger (3) and a short-circuit solenoid valve (5), wherein, following activation of the short-circuit solenoid valve, the method comprises the steps of: a. Incrementing a value of a counter; b. If the value of the counter is greater than a first predetermined threshold value, controlling the short-circuit solenoid valve in a first state, where a heat transfer fluid from the cooling circuit is directed to the heat exchanger.

2. A method according to claim 1, wherein, in step b), the method then performs an inhibition of any subsequent control of the short-circuit solenoid valve (5).

3. A method according to any one of claims 1 to 2, wherein, in step b), the method then emits a first fault code and commands a service indicator light to be switched on.

4. A method according to any one of claims 1 to 3, wherein, following step b), a replacement of the short-circuit solenoid valve and a reset to zero of the meter value are required.

5. A method according to any one of claims 1 to 4, wherein, prior to step b), the method comprises a step a') of: if the value of the counter is greater than a second threshold value, issuing a second fault code.

6. A method according to claim 5, wherein, following step a'), a check for wear of the short-circuit solenoid valve is requested.

7. A method according to any one of claims 1 to 6, wherein, at step a), an increment value of the counter value is different depending on whether the short-circuit solenoid valve goes from the first state to a second stage, where a heat transfer fluid from the cooling circuit is directed in a bypass line to the electric machine, or from the second state to the first state.

8. Powertrain (10) comprising an electric traction machine (1) and an electric machine cooling circuit,

9. the cooling circuit comprising a short-circuit solenoid valve (5) and a heat exchanger (3), wherein the powertrain further comprises a computer (7) arranged to implement a monitoring method according to any one of claims 1 to 7. Motor vehicle comprising a powertrain in which the powertrain is according to claim 8.

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