GB2160291A

GB2160291A - Planetary drive gear

Info

Publication number: GB2160291A
Application number: GB8514941A
Authority: GB
Inventors: Erich Schreiber
Original assignee: Kloeckner Humboldt Deutz AG
Current assignee: Kloeckner Humboldt Deutz AG
Priority date: 1984-06-14
Filing date: 1985-06-13
Publication date: 1985-12-18
Also published as: FR2566085A1; GB8514941D0; DE3422043A1; GB2160291B

Abstract

A planetary gear, e.g. for use as a propeller drive in aircraft, comprises a sun wheel (15), a planet carrier (12) having at least one planet wheel (14), and an outer housing (18) which is in engagement through a hollow wheel (19) with the planet wheel (14). The planet carrier (12) is stationary while the outer housing (18) is arranged to rotate. A lubricant pump (5) is provided in the planetary gearing and lubricant passages (17) are provided in the planet carrier (12), the aircraft propeller being secured directly to the external housing (18). The lubricant pump (5), which is formed for double-flow delivery, sucks in the lubricant from a separately-arranged tank and forces it to the user points and, in a second delivery stream, sucks the lubricant out of the planetary gearing and delivers it through a separate coller back into the tank. Ordinary commercial engine oil or gear oil is used as the coolant. <IMAGE>

Description

SPECIFICATION Planetary gear drive This invention relates to a planetary gear drive comprising a sun wheel, a planet carrier having at least one planet wheel, and an outer housing formed as a hollow wheel, the planet carrier being stationary and the hollow wheel being arranged to rotate.

A planetary gear drive of this construction is known from DE-AS 10 72 485. This Specification describes a drive axle for heavy vehicles or the like where the hub and/or the wheel of the motor vehicle is secured to the hollow wheel of the planetary gear drive. The planetary gear drive comprises a closed planet carrier which is made fast in rotation with a universal joint housing of the vehicle so that the entire planetary gearing, and here also the wheel, are mounted through it. A sun wheel is driven by a drive-input shaft which extends through the planet carrier, while the drive output is provided by the motor vehicle wheel secured directly to the external housing. In this form of planetary gear drive nothing is mentioned concerning a special lubricant supply or cooling. The heat generated by the planetary gearing is dissipated through the external housing directly to atmosphere.

It is an aim of the present invention to improve a planetary gear drive of the above construction by integrating a lubricant pressure supply into the planetary gearing. A further aim is to guarantee adequate cooling of the planetary gearing. Utilisation of the drive as propeller gearing in an aircraft also requires that all parts of the lubricant supply installation, apart perhaps from a separate lubricant tank and a lubricant cooler, be integrated within the planetary gear drive.

With these aims in view, the invention is directed to a planetary gear drive comprising a sun wheel, a planet carrier having at least one planet wheel, and an outer housing formed as a hollow wheel, the planet carrier being stationary and the hollow wheel being arranged to rotate, in which a lubricant pump is arranged within the planetary gear drive in an interspace between the planet carrier and the sun wheel.

The lubricant pump can be conveniently arranged on the main spindle of the planetary gearing in the said interspace between the sun wheel and the planet carrier. The lubricant and/or coolant can, in most cases, be ordinary commercial lubricating oil or gear oil which is cooled down by an oil cooler to the maximum permissible working temperature.

The invention makes it possible, in an advantageous manner, to drive the lubricant pump directly with the sun wheel. Thus, an additional drive arrangement for a separate lubricant pump is entirely eliminated. Furthermore, the lubricant passages to the points of use are short and can therefore be produced easily and cheaply. The planetary gear drive forms a completely self-sufficient unit which requires only a separate supply tank for the lubricant and a lubricant cooler.

In one advantageous construction in accordance with the invention, the housing of the lubricant pump is bolted or screwed to the planet carrier while the rotor of the lubricant pump is driven by the sun wheel directly. It is also advantageous to form the planet carrier directly as the housing of the lubricant pump.

Since the rotor of a rotary lubricant pump can be driven by the sun wheel at an approximately constant rate of rotation, it is possible to use such a rotary pump which can be made as a radial pump, as a centrifugal pump or as a gear pump. Likewise, but with some limitations, axial or semi-axial pumps are suitable for this task.

In another form of the invention, a lubricant pump of tandem construction is used. In this case, the lubricant feed to the lubrication points and cooling points takes place through cast passages and/or through bores in the planet carrier. This helps to ensure that the planetary gearing can work in a self-contained manner, since the lubricant is automatically sucked out of the separately-arranged tank and is automatically delivered back again.

As already indicated, the planetary gear drive is of especial use as a propeller drive in an aircraft. Sometimes the propeller is arranged substantially in the middle of the aircraft fuselage on the outer housing of the planetary gear drive in the form of a by-pass drive system. In this case, the requirement arises for the drive of the propeller from one side of the planetary gear drive and for the mounting of the entire gear complex in the aircraft fuselage on the opposite side of the planetary gear drive. The drive shaft of the sun wheel, which is at the same time the drive-output shaft of the gas turbine, is mostly situated in front of the propeller drive as seen in the direction of flight of the aircraft. Then, logically, the connections for the lubricant cycle are likewise to be arranged on the driveinput side of the planetary gear drive.

However, the field of application of a planetary gear drive in accordance with the invention is not confined solely to propeller drive systems with propellers arranged in the middle of an aircraft fuselage but extends to all current turbo-prop drive systems in aircraft generally. It is also useful for many other tasks where a self-contained planetary gear drive with a rotating external housing is required.

For a further explanation of the invention, reference is made to selected examples shown in the accompanying drawings, in which Figure 1 is a block diagram of a lubricant system of a planetary gear drive in accordance with the invention; and Figure 2 is a longitudinal section through a planetary gear drive in accordance with the invention.

The block diagram of Figure 1 represents the lubricant system of a planetary gear drive in accordance with the invention. The planetary gear drive has essentially two lubricant connections, namely, an inlet 1 and and outlet 2. A tank 3 for the lubricant and a lubricant cooler 4 are arranged outside the planetary gear drive. Lubricant is sucked from the tank 3 by a lubricant pump 5 which has two separate flow paths 6 and 7 situated within the planetary gear drive. The flow path 6 of the lubricant pump forces a stream of lubricant by way of a filter 8 to various points of use 9 in the planetary gear drive. Arranged parallel thereto is a pressure-limiting valve 10 which limits the lubricant pressure to a maximum permissible value.The line in which the pressure-retaining valve 10 is contained can have further branch conduits 22 for external lubricant utilisations connected to it, provided these possess no consumer characteristics.

The entire quantity of lubricant, after it has passed the user points 9 or the pressureretaining valve 10 as the case may be, collects on the external housing of the planetary gear drive. There it is taken up by an intake passage 11 connected to the suction side of the flow-path 7 of the lubricant pump 5 and forced to the outlet 2 of the planetary gear drive. Thence the lubricant is circulated back to the tank by way of a further filter 8 and the lubricant cooler 4.

The two mutually-independent lubricant streams of the two flow paths 6 and 7 of the lubricant pump 5 ensure that-if there is a sufficiently large quantity of lubricant in the tank 3-all user points 9 are constantly supplied with lubricant and the entire quantity of lubricant which collects on the external housing is actually sucked away and conducted through the cooler 4. Ordinary commercial engine oil or gear oil is suitable as the lubricant and coolant.

Figure 2 is a longitudinal section through a planetary gear drive in accordance with the invention. The gear drive incorporates a double-flow lubricant pump 5, and the planet carrier 1 2 is mounted on a central spindle 1 3 of fixed location. This spindle 1 3 is a protrusion on a foundation base or, equally, on an aircraft fuselage. Planet wheels 14 are rotatably mounted on appropriate bearings on the planet carrier 12, there being three planet wheels in this particular instance.Substantially in the middle of the planetary gear drive there is a sun wheel 1 5 which is driven by a drive shaft 1 6 located on the opposite side of the sun wheel from the spindle 1 3. The planet carrier 12, which is assembled from a plurality of parts, extends in a cylindrical form around the sun wheel 1 5.

The pump 5 is bolted or screwed to the planet carrier 1 2 and lies be an interspace between the planet carrier 1 2 and the sun wheel 1 5 on the main axis of the planetary gear drive. The drive of the pump 5 is effected through a co-axial stub shaft 21 directly from the sun wheel 1 5. Passages 1 7 and an annularly-encircling passage 24 are arranged in the planet carrier 1 2 to ensure a lubricant supply to and from the two flow paths 6 and 7 of the pump 5. Individuallyextending pipes or hoses could also be used for the lubricant feed.An external housing 1 8 of the planetary gear drive encloses the planet carrier, and a hollow wheel 1 9 which is in engagement with the planet wheels 14 is nondisplaceably connected with this external housing 18. The external housing 18 is mounted both on the drive side of the planetary gear drive by a radial bearing 23 and on the opposite side by an axial and radial bearing which is not illustrated here. An aircraft propeller (not shown) is bolted or screwed directly to the external housing 1 8.

Mounting of the planet carrier 1 2 on the drive shaft 1 6 can be advantageous for many applications. In this case, the entire load is carried by the drive shaft 1 6. A free-standing propeller arrangement is thereby rendered possible in aircraft by this form of construction.

The lubricant pump 5 sucks in the lubricant through its flow-path 6 and the passages 1 7 from the inlet 1 and forces it, for example, to the bearings of the planet wheels 14 and/or to the radial bearing 23 of the external housing 18. Here all the passages 17, including the annular passage 24, are provided in the planet carrier 1 2. For the cooling of the planetary gear drive the lubricant is, for example, also sprayed directly on to the sun wheel 1 5 through bores 20. The lubricant collects on the periphery of the external housing 1 8. There an intake 11 is arranged to connect with the suction side of the flow-path 7 of the pump 5. The flowpath 7 sucks up the lubricant through this intake 11 and forces it by way of appropriate passages of the planet carrier 1 2 out of the planetary gear drive and, by way of a cooler (not shown), into a lubricant supply tank.

Claims

1. A planetary gear drive comprising a sun wheel, a planet carrier having at least one planet wheel, and an outer housing formed as a hollow wheel, the planet carrier being stationary and the hollow wheel being arranged to rotate, in which a lubricant pump is arranged within the planetary gear drive in an interspace between the planet carrier and the sun wheel.

2. A planetary gear drive according to claim 1, in which the housing of the lubricant pump, which pump is arranged co-axially with the sun wheel, is nondisplaceably connected to the planet carrier, and the lubricant pump is driven by the sun wheel through a coaxial shaft stub.

3. A planetary gear drive according to claim 1 or claim 2, in which the lubricant pump is formed as a rotary pump or as a gear pump.

4. A planetary gear drive according to any one of claims 1-3, in which the lubricant pump is constructed for double-flow delivery.

5. A planetary gear drive according to any preceding claim, in which the lubricant pump is connectable to a dry-sump lubrication system comprising a tank for lubricant which is arranged outside the planetary gear drive.

6. A planetary gear drive according to any preceding claim in which the lubricant delivered by the lubricant pump serves not only for lubrication but also cooling of the planetary gear drive, the lubricant being coolable by a separate lubricant cooler.

7. A planetary gear drive according to claim 4 or any claim appendant thereto, in which the one delivery stream of the lubricant pump is conveyable from a separate lubricant tank through suction conduits to the lubricantpump and through delivery conduits to the lubrication and cooling points of the planetary gear drive, while the other delivery stream of the lubricant pump is conveyable from the outer housing by way of an intake to the lubricant pump and through delivery conduits to a separate lubricant cooler and to the tank.

8. A planetary gear drive according to any preceding claim, in which suction and delivery conduits connected with the lubricant pump include an encircling passage of annular form and are provided as bores or cast passages in the planet carrier.

9. A planetary gear drive according to any preceding claim, in which the planet carrier is mounted on that side of the sun wheel remote from the drive side which includes a nondisplaceable central spindle, while the sun wheel itself, together with its driving shaft, is mounted in overhung fashion in the planetary gearing.

1 0. A planetary gear drive according to any preceding claim, in which lubricant inlets and outlets are connected to the planet carrier on the drive input side of the planetary gearing.

11. A planetary gear drive according to any preceding claim, in which a propeller of an aircraft is connected with the hollow wheel or with the outer housing of the planetary gear drive, and in which the sun wheel is drivable by a gas turbine.

1 2. A planetary gear drive substantially as described herein with reference to Figure 1 and/or Figure 2 of the accompanying drawings.