WO2013124242A1

WO2013124242A1 - Turbine engine including a device for monitoring the supply of oil the rear chamber

Info

Publication number: WO2013124242A1
Application number: PCT/EP2013/053191
Authority: WO
Inventors: Romain Jean Charles MARTIN; Alain Georges PERILLIER; Michel Claude RAOULT; Jean-Luc Verniau
Original assignee: Snecma
Priority date: 2012-02-22
Filing date: 2013-02-18
Publication date: 2013-08-29
Also published as: FR2987077B1; FR2987077A1

Abstract

The present invention relates to a turbine engine including a shaft (17) rotatably mounted on a front bearing (18) and on a rear bearing (19) which are arranged in a front oil chamber (20) and rear oil chamber (21), respectively, said oil chambers being connected to an oil inlet, wherein said turbine engine is characterized in that it includes a device for monitoring the supply of oil to a turbine-engine circuit including a valve (31) suitable for selectively connecting the oil inlet to an oil outlet connected to said rear oil chamber (21), either directly or via a flow restrictor (37), the device further including a pressure sensor (39) suitable for measuring the pressure of the oil at the oil outlet, and a means (38) for controlling the valve (31) on the basis of the oil pressure measured by the pressure sensor (39).

Description

Turbomachine comprising a device for controlling the oil supply of the rear enclosure.

GENERAL TECHNICAL FIELD

The present invention relates to the field of turbomachines, and more specifically the oil chambers comprising the bearings carrying the rotors of these turbomachines. STATE OF THE ART

Turbomachines used in particular for the propulsion of aircraft conventionally present a shaft mounted rotating via bearings disposed in oil chambers located at the front and rear of the turbomachine, connected to an oil inlet in ensuring the supply of oil, and thus the lubrication and cooling of these bearings.

According to the different operating conditions of the turbomachine, the sealing of these oil chambers, and in particular of the rear oil chamber is problematic.

In the first place, when starting, oil is injected cold, which causes leaks. Indeed, the dynamic sealing of the oil chambers is achieved by means of non-contact seals, for example labyrinth seals. However, such seals do not provide dynamic sealing under high pressure conditions in the absence of sufficient expansion, resulting from an increase in temperature.

Therefore, during the injection of cold oil in the rear oil chamber, leaks occur, and oil therefore reaches areas of the turbomachine to which it should not access. In addition, the subsequent rise in the temperature of the turbomachine causes coking all or part of this oil having leaked through the labyrinth seals. These leaks and the resulting coking therefore require regular and specific maintenance operations of the turbomachine, involving disassembly to remove the leaking oil, and in particular the coked oil. PRESENTATION OF THE INVENTION

The present invention aims to remedy this problem, and proposes a turbomachine comprising a shaft rotatably mounted on a front bearing and a rear bearing, arranged respectively upstream and downstream with respect to the direction of flow of air in the turbomachine, said bearings being respectively disposed in a front and rear oil chamber connected to an oil inlet, said turbomachine being characterized in that it comprises a device for controlling the supply of oil to a circuit of a turbomachine comprising a distributor adapted to selectively connect the oil inlet to an oil outlet connected to said rear oil enclosure,

directly,

either through a flow reducer,

the device further comprising a pressure sensor adapted to measure the pressure of the oil at the oil outlet, and distributor control means as a function of the oil pressure measured by the pressure sensor.

According to a particular embodiment, said pressure reducer comprises a diaphragm defining a portion of reduced section.

According to a particular embodiment, said turbomachine further comprises a speed sensor adapted to measure the speed of rotation of the shaft, said control means selectively connecting the oil inlet to the oil outlet according to said measured rotational speed and said measured pressure. The invention finally relates to a method for controlling the supply of oil to a circuit of a turbomachine, in which a turbomachine bearing oil chamber is supplied with oil selectively, either directly or via the intermediate of a flow restrictor, depending on the speed of rotation of the shaft of the turbomachine and the oil pressure in said oil chamber.

As a variant, said oil enclosure is fed via a flow restrictor when the speed of rotation of the shaft is greater than or equal to a minimum threshold value and less than or equal to a maximum threshold value. The supply of the oil chamber via the flow restrictor is then typically performed if the rotational speed of the shaft remains between said minimum and maximum threshold values for at least a given duration.

According to another variant, the oil supply of the rear oil enclosure is carried out directly when the pressure in the rear oil chamber is less than or equal to a pressure threshold value.

PRESENTATION OF FIGURES

Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and nonlimiting, and which should be read with reference to the appended drawings, in which:

- Figure 1 schematically illustrates the structure of a known turbomachine;

FIG. 2 diagrammatically shows the oil supply of oil enclosures of a turbomachine,

FIG. 3 shows a detailed view of a device for controlling the oil supply according to one aspect of the invention, - Figure 4 shows schematically an example of operation of such a device for controlling the oil supply. In all the figures, the common elements are identified by the same reference numerals.

DETAILED DESCRIPTION As a reminder and in order to facilitate the understanding of the invention, FIG. 1 shows a conventional turbomachine structure, comprising from upstream to downstream in the direction of the gas flow, a fan 10 defining a air intake provided with a fan 11, one or more stages of compressors 12, for example a low pressure compressor and a high pressure compressor, a combustion chamber 13, one or more stages of turbines, for example a high pressure turbine 14 and a low pressure turbine 15, and a gas exhaust nozzle.

A shaft 17 rotates the fan 11 of the fan 10, its rotation being in particular caused by the compression, combustion and expansion cycle of the air passing through the turbomachine which drives the turbines 14 and 15 connected to the shaft 17.

The shaft 17 is rotatably mounted via bearings, for example tapered or roller bearings; a front bearing 18 disposed near the blower 10, and a rear bearing 19 disposed near the low pressure turbine 15.

These two front 18 and rear 19 bearings are respectively disposed in a front oil chamber 20 and a rear oil chamber 21, connected to an oil inlet ensuring the supply of oil, and therefore the lubrication and cooling bearings 18 and 19.

FIG. 2 diagrammatically shows the oil supply of the front and rear oil chambers 21 respectively comprising the bearing front 18 and rear 19 of the shaft 17 of a turbomachine as shown previously in Figure 1.

A pump 22 draws oil from a tank 23, and thus supplies the front and rear oil chambers 20 with oil.

The invention consists of a device for controlling the oil supply 30, arranged here so as to control the supply of oil to the rear oil enclosure 21.

FIG. 3 presents a detailed view of an embodiment of this device for controlling the oil supply 30.

This figure shows the pump 22 shown above, as well as the rear oil enclosure 21 in which is disposed the rear bearing 19 mounted around the shaft 17 of a turbomachine.

The device for controlling the oil supply 30 as shown comprises a distributor 31 having an inlet 32 and two outlets 33 and 34, this dispenser being able to alternate between two positions:

a first position PI in which the input 32 is connected to the first output 33 while the second output 34 is closed,

a second position P2 in which the input 32 is connected to the second output 34, while the first output 33 is closed. The distributor 31 is maintained by default in its first position PI under the effect of return means 35, typically resilient return means such as a spring, which oppose an actuator 36, for example a pneumatic actuator, hydraulic or electrical such as a cylinder for tilting the distributor 31 in its second position P2.

The first outlet 33 of the distributor 31 is connected directly to the target oil enclosure, here the rear oil enclosure 21, while the second outlet 34 of the distributor 31 is connected to the target oil enclosure 21 via a flow restrictor 37; typically a diaphragm.

Thus, when the distributor 31 is in its first position PI, the target oil enclosure, for example the rear oil enclosure 21 is directly supplied with oil by the pump 22, while when the distributor 31 is in its second position P2, the oil flow supplying the rear oil chamber 21 is reduced because of the flow restrictor 37 which is interposed between the pump 22 and the rear oil enclosure 21.

The actuator 36 is controlled by a computer 38, which is typically connected to a pressure sensor 39, a temperature sensor 40 and a speed sensor 41 of rotation of the shaft 17 of the turbomachine.

The computer 38 drives the actuator 36, and therefore the movement of the distributor 31 in its first or in its second position P2 as a function of the information recorded by the sensors 39, 40 and 41.

The pressure sensor is for example a sensor delivering an intensity ranging from 4 mA to 20 mA, for relative pressures measured ranging from 0 to 20 bar.

It is understood that the number and types of sensors associated with the computer 38 may vary depending on the parameters that are to be taken into account for controlling the distributor 31.

FIG. 4 diagrammatically represents an example of control as a function of the speed of the turbomachine, that is to say as a function of the speed of rotation of the shaft 17 of the turbomachine forming the abscissa axis.

The two possible states of the distributor 31 are shown on the ordinate axis, respectively the first and second positions P2 described above, here marked by PI for the first position PI, and P2 for the second position P2. Thus, in the first position PI, the hydraulic pump 22 directly feeds the oil chamber, and in the second position P2, the flow rate supplied by the pump 22 to the oil chamber is reduced because of the passage through a flow reducer 37.

During a rise in speed, the distributor 31 is by default in its first position Pl. When the speed exceeds a minimum threshold value Rmin during at least a first time delay T1, the distributor 31 switches to its position P2.

The first timer Tl ensures a stabilization time of the regime, so that the distributor 31 does not move from the first position PI to the second position P2 for example in the case of punctual peaks speed. The speed of the turbomachine must therefore be greater than the threshold value Rmin for a duration at least equal to the first time delay T1 so that the position switching occurs.

Following this changeover from the first position to the second position P2 of the distributor 31, while continuing to ramp up, the turbine engine reaches a maximum threshold value Rmax, from which the distributor 31 switches from its second position to its first position Pl.

During a reduction in engine speed, considering an initial engine speed having a value greater than Rmax, the distributor 31 is initially in its first position Pl.

When the speed of the turbomachine decreases and reaches the maximum threshold value Rmax, the distributor switches from the first to its second position P2, following the flow of a second timer T2 during which the speed is below the maximum threshold value Rmax .

As during the ramp-up, the second timer T2 makes it possible to ensure that the tilting of the distributor 31 is realized only in the case of a stable situation below the value Rmax, and not on a one-off drop in speed. .

Following this changeover to second position P2, the steady state continues to reach the minimum threshold value Rmin. When the RPM is below this value Rmin, the distributor 31 switches back to its first position Pl.

The values of the first and second time delays T1 and T2 may be identical or different.

The pilot example shown in FIG. 4 thus makes it possible to ensure a reduced oil supply for the targeted vessel; typically the rear oil chamber 21, whether during the rise or fall in speed.

In the event of ups and downs, the time delays T1 and T2 make it possible to avoid multiple switching operations for short periods of time.

The threshold values are for example the following:

Rmin: 3500 rpm,

Rmax 5000 rpm

with delays Tl and T2 which are typically identical and equal to 5 seconds.

The pilot example presented in FIG. 4 is based on a measurement of the speed of the turbomachine only.

It is understood that this example can be adapted in a manner similar to a control as a function of temperature and / or pressure, in addition to or instead of the speed of the turbomachine.

The control according to the regime shown in FIG. 4 can for example be coupled with a measurement of the pressure in the rear oil enclosure 21, adapted to modify the control of the oil supply in the event of oil pressure. too low in this rear oil enclosure.

For example, a pre-alarm can be provided for a relative oil pressure of the order of 0.3 bar, and an alarm can be triggered for a relative oil pressure of the order of 0.2 bar in the rear oil chamber. In the case where the relative pressure in the oil enclosure considered (for example the rear oil enclosure 21) reaches a threshold value, for example 0.2 bar, the distributor 31 is then automatically returned to its first position PI, so as to re-increase the pressure in this oil chamber. Similarly to the timers T1 and T2 shown above, this switchover in the case of pressure lower than a pressure threshold value may be conditioned by the fact that the measured pressure remains below the pressure threshold value for a predefined period; typically equal to 2 seconds.

In the case of the alarm and / or the pre-alarm, indicators can alert the user, for example visual or audible indicators. The device can have similar characteristics with appropriate temperature threshold values, in the same way as for the pressure and the speed.

The device can be adapted to many types of turbomachines, by simply changing the oil supply of a bearing oil chamber supporting the shaft, and in particular the rear oil chamber. Calibration of the device following its implementation on a given turbomachine, for example by simulating conditions reproducing speeds of the order of 1000 revolutions / minute and 10000 revolutions / minute.

The device can be presented in the form of a transportable kit that can be mounted on an existing turbomachine.

Such a kit thus comprises on the one hand the distributor, the sensors and the input and output ducts, and on the other hand the control means comprising the actuator, the computer, as well as, for example, display means . The device and the method presented thus make it possible to limit the pressure in an oil chamber, and in particular in the rear oil chamber of a turbomachine shaft bearing, in order to avoid leaks that could occur when the turbomachine is not in steady state in case of too high pressure in the bearing oil chambers of a turbomachine shaft, and in particular in the rear oil chamber.

The device and the method presented are thus advantageous in terms of the amount of oil required for the operation of the turbomachine and in terms of the time required for maintenance operations.

By way of example, considering an endurance test lasting approximately 5 hours, this duration can be up to 10 hours for certain tests, for a CFM56 type turbine engine, the device and the method presented allow to save about 600 liters of oil, in addition to saving the time required for disassembly, cleaning and reassembly of the turbomachine, which can lead to its immobilization for several days.

Claims

claims

1. Turbomachine comprising a shaft (17) rotatably mounted on a front bearing (18) and a rear bearing (19), arranged respectively upstream and downstream with respect to the direction of flow of the air in the turbomachine (1) , said bearings being respectively disposed in a front (20) and rear (21) oil chamber connected to an oil inlet, said turbomachine being characterized in that it comprises a device for controlling the oil supply, a circuit of a turbomachine comprising a distributor (31) adapted to selectively connect the oil inlet to an oil outlet connected to said rear oil enclosure (21),

directly,

either via a flow reducer (37),

the device further comprising a pressure sensor (39) adapted to measure the pressure of the oil at the oil outlet, and control means (38) of the distributor (31) as a function of the measured oil pressure by the pressure sensor (39).

2. A turbomachine according to claim 1, wherein said pressure reducer (37) comprises a diaphragm defining a portion of reduced section.

3. Turbomachine according to one of claims 1 or 2, further comprising a speed sensor (41) adapted to measure the rotational speed of the shaft (17), said control means (38) selectively connecting the supply of oil to the oil outlet according to said measured rotational speed and said measured pressure.

4. A method for controlling the supply of oil to a circuit of a turbomachine, in which a turbomachine bearing oil chamber is selectively supplied with oil, either directly or via a flow reducer, depending on the speed of rotation of the turbomachine shaft and the oil pressure in said oil chamber.

5. The method of claim 4, wherein said oil chamber is fed via a flow restrictor when the speed of rotation of the shaft is greater than or equal to a minimum threshold value and less than or equal to a maximum threshold value.

6. Method according to claim 5, wherein the supply of the oil chamber via the flow restrictor is performed if the rotational speed of the shaft remains between said minimum and maximum threshold values during the minus a given duration.

7. Method according to one of claims 4 to 6, wherein the oil supply of the rear oil chamber is performed directly when the pressure in the rear oil chamber is less than or equal to a threshold value. pressure.