GB2417701A

GB2417701A - Centrifugal filter with annular motor

Info

Publication number: GB2417701A
Application number: GB0419422A
Authority: GB
Inventors: Michael James Watts; Michael Willcock; Keith William Barter
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2004-09-02
Filing date: 2004-09-02
Publication date: 2006-03-08
Anticipated expiration: 2024-09-02
Also published as: GB2417701B; GB0419422D0

Abstract

A centrifugal filter for removing contaminants from engine oil includes a housing enclosure 1 formed by a base 2 adapted to be fixed to an engine and a removable cover 3 inside which a rotary canister 4 is rotatably and separately mounted around a substantially vertical fixed shaft 5 where is distributed the engine oil. The housing further comprises a drive motor 12 for driving the rotary canister 4. The drive motor 12 comprises a rotor 13 and a stator 14. The stator is arranged in the removable cover/ cage 3 and the rotor 13 around the canister 4 in such a way that the centrifugal filter and drive motor 12 are integrated. Preferably the cover/ cage 3 includes a flexible strap which is adapted to be wrapped around the canister 4, permanent magnets being securely embedded along the length of the strap.

Description

241 7701.. . . - 1 Centrifual filter The present invention relates to a

powered centrifugal filter for removing contaminants from fluids using centrifugal force. In particular, the invention relates to the arrangement of a drive system in the centrifugal oil filter for Internal combustion engines and a canister for such a centrifugal filter.

It is known, for example from W09109251, to provide for an engine lubricating oil system a centrifugal oil filter which is placed in a lubrication oil flow circuit such that oil passes through and is centrifuged by the centrifugal filter. The centrifugal filter has a rotor body, referred to also as a filter canister, and a powered drive system for rotating the filter canister from the engine by a belt and pulley or gear arrangement By such an arrangement, the rotation of the filter canister is independent of the oil flow through the centrifugal filter. However, this known type of drive system is problematic in many respects For instance, the requisite rotary speed range of the filter canister is achieved by the use of gears or a belt and pulley drive, as a result of which, the installation in an engine compartment of a vehicle is made difficult requiring extensive modifications to the engine. Furthermore, the filter rotation speed is a function of engine speed so that at low engine speeds the centrifugal force might be insufficient for removing contaminants from the engine oil.

It is also known from US6213929 to provide a centrifugal filter comprising a filter head, a housing which is able to mate with the filter head, a filter canister disposed within the housing and rotatable relative to the housing about an axis of rotation, a brushless direct current electric motor for rotating the filter canister and a controller which controls operations of the motor. The brushless DC motor carried by the filter head has a rotatable output shaft detachably coupled with the filter canister for rotating the filter about the axis of rotation. Since the motor shaft of the brushless DC motor necessarily has to be coupled mechanically to the filter canister in order to operate the e ace e C C C. centrifugal filter, the overall length of centrifugal filter is relatively large and is made difficult to install onto a modern vehicle engine bay where available space is very restricted. In addition with this known type of construction the weight of the centrifugal filter is relatively high as each drive part has its own bearing system. As a result the cost of the overall system is increased.

It is an object of this invention to create a centrifugal filter where the aforementioned disadvantages are alleviated.

According to a first aspect of the invention there is provided a centrifugal filter for removing contaminants from engine oil, including a housing adapted to be fixed to an engine, a rotary canister rotatably and separately mounted inside the housing around an axis, an inlet and an outlet for the flow of the engine oil, and a drive motor for driving the rotary canister, the drive motor comprising rotary elements and static elements, wherein the static elements are arranged in the housing and the rotary elements are arranged on the canister.

One advantages of the present invention is that the drive motor is integrated to the centrifugal filter in a compact manner using the shaft drive around which the canister rotates.

Preferably the rotating elements of the drive motor comprise permanent magnets.

The permanent magnets may be attached as a removable cage around the canister.

More preferably, the cage includes a flexible strap, which Is adapted to be wrapped snugly about the canister, and on which permanent magnets are securely embedded along the length of the strap.

ace e e e e e . . . . e e c . ë e Also preferably the static elements of the drive motor are capable of being controlled in order to achieve different rotary speeds of the rotary elements of the drive motor.

The invention also provides, according to a second aspect thereof, a rotary canister for a centrifugal filter as above-mentioned, the canister having permanent magnets so that in use, i.e. when assemble, the permanent magnets form the rotary elements of the drive motor.

The Invention will now be described by way of example with reference to the accompanying drawings, of which: Fig. 1 is a sectional elevation through a centrifugal oil filter of the present invention, and Fig. 2 Is a block diagram of a lubricating oil system of an internal combustion engine including the centrifugal oil filter according to Fig.1.

Referring to the drawings, In particular Fig.1, there is shown a centrifugal oil filter for removing particulate contaminants from engine oil in an automobile internal combustion engine. The centrifugal oil filter generally includes a housing enclosure 1 formed by a base 2 and a removable cover 3 inside which a rotary canister 4 is rotatably and separately mounted around a substantially vertical fixed shaft 5. The shaft 5 also serves to retain, in a known manner, the cover 3 with respect to the base 2 in a fluid-tight manner by means of a cap nut 6 arranged at the top of the cover 3 and which is screwed onto the externally-threaded end of the shaft 5. The opposite end of the shaft 5 is screwed on the central part of the base 2.

The base 2, which is adapted to be fitted to the engine, is equipped with an inlet 7 and an outlet 8 for the oil flow. Arrows indicate the flow direction of oil. The inlet 7 is c e c C C C c cat ce c c.e C C C C C C. C connected to the oil pump of the engine in order to deliver oil under pressure to the inside of the rotary canister 4 and the outlet 8 is connected to the engine oil passages The base 2 has an annular chamber 9, formed in the base 2 around an extended part 2a where the shaft 5 is screwed, which provides a collection zone for oil returning to the engine through the outlet 8.

The shaft 5 further includes a supply duct 5a along a part of its length and provides passage for the oil which passes through the base inlet 7.

The rotary canister 4 is generally cylindrical, having an exterior peripheral cylindrical surface 4a, a domed upper end wall 4d and a generally flat lower end wall 4e. An inner tubular member 4b extends axially between the end walls 4d, 4e and carries bearing bushes 10, 11 at its ends to support the canister 4 with respect to the shaft 5 so that the rotary canister can 4 rotates freely. The inner tubular member 4b has apertures 41b which direct oil delivered by the shaft supply duct 5a inside the rotary canister and the lower end wall 4e has exit ports or jets 4f where oil can exit 1 5 tangentially.

The centrifugal filter and the rotary canister as so far described are conventional.

Thus, oil from the engine's oil pump is delivered to the rotary canister 4 by the shaft supply duct 5a and is ejected through the Jets 4f such that the rotary canister 4 spins at such speed as to effect centrifugal separation of particulate contaminants from the oil passing through it. The oil circulates through the rotary canister 4 to the annular outlet 9. As the oil circulates through the rotary canister 4 dirt and other impurities Will be centrifuged outwardly and deposited on the inner peripheral surface 4c of the canister 4. From the annular chamber 9, the oil passes through the outlet 8 in the base 2 from where is conducted to the engine. . * r a

c t I .e t It will be appreciated that In conventional engines the oil pump is mechanically driven by the engine so that its output, i.e. flow rate, is dependent on the speed of the engine Hence the speed of rotation of the rotary canister 4 is dependent on engine speed. To overcome this problem and to allow the rotary canister 4 to rotate independently of the engine oil flow, the centrifugal oil filter further includes a drive motor 12 The drive motor 12 comprises rotary elements forming a rotor 13 and static elements forming a stator 14. The drive motor 12 has no commutator or slip rings, e.g. it Is a brushless direct current motor. The rotary elements of the rotor 13 comprise permanent magnets which are embedded on the outer peripheral surface 4a of the Barrister 4. The stator 14 is separate from the rotor 13 and is fixed in the removable cover 3. The static elements of the stator 14 comprise a laminated core 14a and a stator winding 14b. The stator 14 is retained inside the cover 3 by means of a snap ring 15 which is accommodated in a groove formed in the inner surface of the cover 3.

An electrical connector plug 16 is mounted on the outer surface of the cover 3 so that current can be supplied to the drive motor 12.

As shown in Fig. 2, the supply of electrical power to the stator winding 14b of the stator 14 is by a power supply 20 controlled by a filter control unit 17 in order to achieve different rotary-speed ranges for the rotary canister 4 according to the operating conditions of the engine 18, in particular the engine oil flow. An engine control unit 19 which receives Information from various sensors connected at different components of the engine is connected to the filter control unit 17 so that it can send Instructions to the filter control unit 17 to select a satisfactory speed range of the drive motor 12 according to the different operating conditions of the engine in order to filter at the optimum efficiency, in particular when the oil is cold or when the engine is starting.

It will be appreciated that by assembling the removable cover 3 around the rotary canister 4 a centrifugal oil filter is obtained having a drive motor which is integrated. 4.e c

.it, e . 4 < C - 6 In a modification, the permanent magnets forming the rotor 13 of the drive motor are arranged removably around the canister 4. The permanent magnets are attached as a removable cage to the rotary canister 4, thus enabling the magnets to be reused when the rotary canister 4 is discarded during servicing. The cage includes a flexible strap, which is adapted to be wrapped snugly about the outer rotary canister 4, and on which permanent magnets are securely embedded along the length of the strap.

As described hereinbefore, according to the invention, several practical effects can be obtained. For example, the drive motor is integrated to the centrifugal rotor using the same bearings as the rotary canister. Such an arrangement is easily dismountable for the purpose of service. Also, since the drive motor is integrated around the rotary canister 4, the centrifugal filter is compact. Furthermore, the arrangement of permanent magnets, both permanently or removably, around the rotary canister 4 can attract any ferromagnetic particles in the oil and keep them inside the rotary canister 4.

Claims

ëve e e e8 e e e I e I I e I e bee I .' e e e e e e e ce e CLAIMS

1. A centrifugal filter for removing contaminants from engine oil, including a housing adapted to be fixed to an engine, a rotary canister rotatably and separately mounted inside the housing around an axis, an inlet and an outlet for the flow of the engine oil, and a drive motor for driving the rotary canister, the drive motor comprising rotary elements and static elements, wherein the static elements are arranged in the housing and the rotary elements are arranged on the canister.

2. A centrifugal filter as claimed In claim 1, wherein the rotating elements of the drive motor comprises permanent magnets.

3. A centrifugal filter as claimed in claim 2, wherein the canister comprises an outer peripheral surface in which the permanent magnet are embedded.

4. A centrifugal filter as claimed in claim 2, wherein the permanent magnets are attached as a removable cage around the canister.

5. A centrifugal filter as claimed in claim 4, wherein the cage includes a flexible strap, which is adapted to be wrapped snugly about the canister, and In which permanent magnets are securely embedded along the length of the strap.

6. A centrifugal filter as claimed in any preceding claim, wherein the static elements of the drive motor are capable of being controlled in order to achieve different rotary speeds of the rotary elements of the drive motor.

7. An engine incorporating a centrifugal filter according to any foregoing claim. . .

.. .. . c: : : :: .. -

8 8. A rotary canister for a centrifugal filter as claimed in claim 1, the canister having permanent magnets so that in use the permanent magnets form the rotary elements of the drive motor.

9. A rotary canister substantially as described herein with reference to the Fin. 1

10. A centrifugal filter substantially as described herein with reference to the accompanying drawings.