CN217841847U - Crankshaft box body and gear cover assembly and engine and aircraft thereof - Google Patents

Abstract

The utility model discloses technical scheme discloses a bent axle box and gear cover assembly and engine, aircraft thereof, including the bent axle box that is used for bearing bent axle and balance mechanism, install in dismantled and assembled in the bent axle box protecgulum of bent axle box one side and dismantled and assembled install in the bent axle box protecgulum for with the output shaft gear cover of the opposite side of bent axle box installation, wherein, the bent axle box protecgulum with the output shaft gear cover bears the transmission assembly jointly, just connecting rod piston mechanism has still been seted up on the bent axle box and has been laid the space. The utility model discloses a closely ingenious cooperation with the structure between crankcase body, crankcase body protecgulum and the output shaft gear cover, can realize bearing the function of gear integrated structure bent axle, balance mechanism, transmission and final output shaft ring flange simultaneously.

Description

Crankshaft box body and gear cover assembly and engine and aircraft thereof

Technical Field

The utility model belongs to the technical field of the crankcase body assembly technique and specifically relates to a crankcase body and gear cover assembly and engine, aircraft thereof are related to.

Background

In recent years, unmanned aerial vehicles that use a four-cylinder piston engine for a small-sized manned aircraft to directly drive a propeller have appeared on the market. However, most of the four-cylinder piston engines for small-sized passenger aircraft are arranged in a horizontally opposed manner, and an unmanned aerial vehicle equipped with an in-line four-cylinder piston engine has not yet been widely used.

The horizontal opposed piston engine for driving a large industrial unmanned aerial vehicle or a small manned aircraft has the defect that main expensive parts of the engine, including a cylinder body, a cylinder head, a cylinder cover, a cam shaft and the like, need to be arranged in bilateral symmetry, so that the number of the parts is increased and the dead weight is increased. Therefore, it is not necessary to adopt a horizontally opposed piston engine for mass-production and cost-reduction piston engines for automobiles. Of course, the high cost is one of the disadvantages for unmanned aerial vehicles and small manned aircraft.

The traditional four-cylinder in-line piston engine crankcase can only be provided with an engine crankshaft assembly generally, but cannot be provided with a transmission device assembly at the same time, and when an engine is provided with a balancing device, the requirement for simultaneously mounting the balancing device cannot be met.

Disclosure of Invention

The utility model provides a technical problem be traditional four jar in-line piston engine crankcase, generally can only install engine crankshaft assembly, and can't install the transmission assembly simultaneously, when the engine set balancing unit, also can't satisfy the demand of installing balancing unit simultaneously.

For solving foretell technical problem, the utility model discloses technical scheme provides a crankcase body and gear cover assembly, wherein, including the crankcase body that is used for bearing bent axle and balancing unit, install dismantled and assembled in the crankcase body protecgulum of crankcase body one side and, install dismantled and assembled in the crankcase body protecgulum for with the output shaft gear cover of the opposite side of crankcase body installation, wherein, the crankcase body protecgulum with the output shaft gear cover bears the transmission assembly jointly, just the space is laid to the connecting rod piston mechanism has still been seted up on the crankcase body.

Optionally, the crankcase body includes a pair of upper and lower crankcase bodies with symmetrical structural parts, a crankshaft installation space for installing a crankshaft is formed at a corresponding position of the upper and lower crankcase bodies, a balance mechanism installation space is formed at two sides of the crankshaft installation space, and a left and right balance device central shaft installation hole is formed at the balance mechanism installation space of the lower crankcase body.

Optionally, the balancing device mounting space includes left and right balancing device mounting spaces, and a left balancing device idler mounting space is formed in the upper case of the crankshaft at a position above the left balancing device mounting space. And a left balancing device idler central shaft mounting hole is formed in the mounting space of the upper box body left balancing device idler.

Optionally, the crankshaft is mounted with a balancing mechanism driving gear near the balancing device mounting space, the balancing mechanism driving gear is meshed with a right balancing device and a left balancing device idler gear, and the left balancing device is meshed with the left balancing device idler gear.

Optionally, the transmission assembly is a three-stage gear reduction mechanism, the crankcase carries a first-stage gear reduction mechanism of the transmission assembly, the crankcase front cover and the output shaft gear cover jointly carry a second-stage gear reduction mechanism of the transmission assembly, and the crankcase front cover and the output shaft gear cover carry a third-stage gear reduction mechanism of the transmission assembly.

Optionally, the crankshaft is provided with a transmission driving gear near the transmission assembly, the transmission driving gear is engaged with a first-stage gear reduction mechanism, the first-stage gear reduction mechanism is engaged with a second-stage gear reduction mechanism, and the second-stage gear reduction mechanism is engaged with a third-stage gear reduction mechanism.

Optionally, a gear shaft of the first stage gear reduction mechanism is installed in the upper crankcase and the lower crankcase, a gear shaft of the second stage gear reduction mechanism is installed in the upper crankcase, the front cover of the crankcase and the output shaft gear cover, and a gear shaft of the third stage gear reduction mechanism is installed in the front cover of the crankcase and the output shaft gear cover.

In order to solve the technical problem, the utility model discloses technical scheme still provides an engine, installs the aforesaid arbitrary crankcase and gear cover assembly.

In order to solve the technical problem, the utility model discloses technical scheme still provides an aircraft, installs foretell engine.

The utility model discloses technical scheme's beneficial effect is:

the utility model discloses a closely ingenious cooperation with the structure between crankcase body, crankcase body protecgulum and the output shaft gear cover, can realize bearing the weight of gear integrated configuration bent axle, turn into the continuous rotary motion of bent axle through the bent axle with the upper and lower linear motion of connecting rod piston, realize piston engine's basic function. The requirement of bearing and installing the balance mechanism can be met, and the vibration problem of the four-cylinder in-line piston engine is solved by driving the left balance device and the right balance device which are arranged in the crankcase body through the gear integrated with the crankshaft structure. The transmission device assembly can be borne and installed, the transmission device assembly formed by the multi-stage speed reducing mechanism is driven through the gear integrated with the crankshaft structure, the basic function of engine speed reduction is achieved, the problems of high power and miniaturization of the piston type aircraft engine are solved, and the carrying performance of an aircraft is improved. It can also carry a flange for mounting the final output shaft to deliver power from the engine to the propeller of an aircraft (e.g., a fixed wing aircraft) or to a power input device of an aircraft (e.g., a reduction gear of a helicopter).

Drawings

FIG. 1 is a schematic structural view of a crankcase and a gear cover assembly according to an embodiment of the present invention;

FIG. 2 is an exploded view of the crankcase body and the gear cover assembly according to the embodiment of the present invention;

FIG. 3 is an assembly diagram of the lower case of the crankshaft and the balance mechanism in the embodiment of the present invention;

FIG. 4 isbase:Sub>A sectional view taken along line A-A of FIG. 3;

fig. 5 is a schematic view of the installation positions of the crankshaft and the balance mechanism in the embodiment of the present invention;

FIG. 6 is a side view of the crankcase body and gear cover assembly according to an embodiment of the present invention;

FIG. 7 is a cross-sectional view taken along line B-B of FIG. 6 (without the upper crankcase);

FIG. 8 is a schematic diagram showing the separation of the lower case and the upper case of the crankshaft according to the embodiment of the present invention;

FIG. 9 is a schematic structural view of an upper case of a crankshaft according to an embodiment of the present invention;

fig. 10 is a schematic structural diagram of an output shaft gear cover according to an embodiment of the present invention.

The specific implementation mode is as follows:

the present invention will be further described with reference to the accompanying drawings and specific embodiments, which are not intended to limit the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

In the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact between the first and second features, or may comprise contact between the first and second features not directly. Also, the first feature "on," "above" and "over" the second feature may include the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is at a higher level than the second feature. The first feature being "under," "beneath," and "under" the second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

Referring to fig. 1, 2 and 3, an embodiment of a crankcase and a gear cover assembly 100 is shown, wherein the assembly includes a crankcase 1/2 for carrying a crankshaft 300 and a balance mechanism 400, a crankcase front cover 3 detachably mounted on one side of the crankcase, and an output shaft gear cover 4 detachably mounted on the other side of the crankcase front cover 3 opposite to the side mounted with the crankcase, wherein the crankcase 1/2 carries the crankshaft 300 and the balance mechanism 400, and the crankcase is further provided with a connecting rod and piston mechanism accommodating space 201 (as shown in fig. 5).

As shown in fig. 3, 4 and 5, in the present embodiment, the crankcase body includes a pair of upper crankcase body 2 and lower crankcase body 1, the structural parts of which are symmetrical, a crankshaft installation space 101 for installing the crankshaft is formed at the corresponding position of the upper crankcase body 2 and the lower crankcase body 1, installation spaces of a left balance device 403 and a right balance device 401 are formed at two sides of the crankshaft installation space 101, and a balance device central shaft installation hole 104 is opened at the installation space of the left balance device 403 and the right balance device 401 in the lower crankcase body 1 (as shown in fig. 5, only the installation hole of the right balance device central shaft 404 is marked in fig. 5). The balancer installation space includes a left balancer installation space 102 and a right balancer installation space 103, and the crankcase upper case 2 is formed with a left balancer idler installation space 202 at a position above the left balancer installation space 102. The crankshaft 300 is mounted with a balance mechanism driving gear 302 near the balance device mounting space, the balance mechanism driving gear 302 is engaged with a right balance device 401 and a left balance device idler 405, and a left balance device 403 is engaged with the left balance device idler 405.

As shown in fig. 6, 7, 8, 9 and 10, in the present embodiment, the crankcase body and gear cover assembly 100 carries the transmission assembly 500, the transmission assembly 500 is a three-stage gear reduction mechanism, the crankcase body 1/2 carries the first-stage gear reduction mechanism 501/502/503 of the transmission assembly, the crankcase body 1/2 and the crankcase body front cover 3 and the output shaft gear cover 4 carry the second-stage gear reduction mechanism 504/505/506 of the transmission assembly, and the crankcase body front cover 3 and the output shaft gear cover 4 carry the third-stage gear reduction mechanism of the transmission assembly. The crankshaft is provided with a transmission driving gear 301 near the transmission assembly, the transmission driving gear 301 is meshed with a first-stage gear reduction mechanism speed reduction gear 501, a first-stage gear reduction mechanism driving gear 503 is meshed with a second-stage gear reduction mechanism speed reduction gear 504, and a second-stage gear reduction mechanism driving gear 506 is meshed with a third-season gear reduction mechanism speed reduction gear 507. The gear shaft 502 of the first stage gear reduction mechanism is installed in the upper case 2 and the lower case 1 of the crankshaft, the gear shaft 505 of the second stage gear reduction mechanism is installed in the upper case 2 of the crankshaft, the front cover 3 of the crankcase, and the gear cover 4 of the output shaft, and the gear shaft 508 of the third stage gear reduction mechanism is installed in the front cover 3 of the crankcase and the gear cover 4 of the output shaft.

The technical scheme of the embodiment also provides an engine which is provided with any one of the crankcase body and the gear cover assembly.

The technical scheme of the embodiment also provides an aircraft provided with the engine.

The features and functions of the present invention will be further understood from the following description.

The integral structure of the special box body for the aircraft engine adopts the thin-wall cast alloy structure box body, compared with the common engine box body, the self weight of the box body can be reduced by 40-50%, and the attack-weight ratio (the maximum power of the engine/the self weight of the engine body) of the aircraft engine is greatly improved. The results of the embodiment of the EDOS-1300 engine (1340 ml exhaust gas volume, natural air intake) show that the weight attack ratio reaches 1.41kW/kg, which is more than 30% higher than that of the similar engine (such as ROTAX912 produced by Austria, 1200 ml exhaust gas volume, natural air intake).

The upper crankshaft box body 2 and the lower crankshaft box body 1 jointly bear and mount the crankshaft 300 with the gear integrated structure, the right balance device 401 arranged on the right side of the crankshaft and the left balance device idler wheel 405 arranged on the left side of the crankshaft are driven by the balance mechanism driving gear 302 arranged on the rear portion of the middle of the crankshaft, the left balance device 403 is driven by the left balance device idler wheel 405, the left balance weight and the right balance weight rotate reversely at twice rotating speed, second-order vibration of the four-cylinder in-line piston engine is eliminated, a zero-vibration structure of the aircraft engine is achieved, and basic technical support is provided for the four-cylinder in-line piston engine to replace a traditional horizontal opposed piston engine.

The transmission device assembly 500 is borne and mounted by four main structural components, namely a crankshaft upper box body 2, a crankshaft lower box body 1, a crankshaft box body front cover 3, a final output shaft gear cover 4 and the like, and the transmission device assembly 500 formed by a multi-stage gear mechanism is driven by a transmission device driving gear 301 arranged at the front end of a crankshaft, so that the basic function of engine deceleration is realized, and basic technical guarantee is provided for high speed and high power of an aeroengine; meanwhile, the length size of the engine is minimized through reasonable configuration of a multi-stage gear structure, the center line of the final output shaft flange 509 of the engine is overlapped with the center of gravity of the engine in the left and right directions of the engine, the left and right stability of the engine is improved, and the carrying performance of the in-line piston engine on an aircraft is improved.

The bearing of the final output shaft 508 and the flange 509 is realized by the crankcase front cover 3 and the final output shaft gear cover 4 arranged outside the crankcase front cover, the engine power is transmitted to the aircraft, and the final output shaft flange 509 and the final output shaft 508 are of an integrated structure (but not limited to an integrated structure).

The crankcase and gear cover assembly 100 of the present embodiment will be described in detail below.

Fig. 1 is an overall configuration diagram of a crankcase body and a gear cover dedicated to an aircraft engine according to the present embodiment. The special crankcase and gear cover assembly 100 is mainly composed of the following parts: the crankshaft lower box body 1, the crankshaft upper box body 2, a crankshaft box body front cover 3 and an output shaft gear cover 4. Fig. 2 is a perspective exploded view (exploded view) of the dedicated crankcase and gear cover assembly 100. Wherein, the bolt 5 is a fastener which is positioned in the five crankshaft journal bearing mounting holes and is used for connecting the lower crankshaft box body 1 and the upper crankshaft box body 2, the bolt 6 is a fastener which is used for connecting the peripheries and other parts of the lower crankshaft box body 1 and the upper crankshaft box body 2, the bolt 7 is a fastener for connecting the front cover 3 of the crankshaft box body and the 1/2 of the upper crankshaft box body, and the bolt 8 is a fastener for connecting the final output shaft gear cover 4 and the front cover 3 of the crankshaft box body.

The following embodiments are provided to illustrate how the crankcase and gear cover assembly 100 can be loaded and loaded with the following mechanisms: a gear integrated structure crankshaft 300; a balance mechanism 400; the transmission assembly 500 and the final output shaft flange 509.

Fig. 3 is a perspective view showing the relative relationship between the lower case 1, the crankshaft 300 and the balance mechanism 400, and the upper case 2 (not shown) is fastened to the lower case 1 (as shown in fig. 1) and is connected to the lower case by bolts 5 and 6. Crankshaft 300 is provided with a transmission drive gear 301 at the front end of crankshaft 300 and a balance drive gear 302 at the rear end (offset to the middle) of crankshaft 300, in addition to the crankshaft journal, crank and crank pin of a typical piston engine.

Fig. 4 isbase:Sub>A sectional view taken along linebase:Sub>A-base:Sub>A of fig. 3, showing the relative mounting relationship of the upper and lower cases 1/2 of the crankshaft, the balance drive gear 302 of the crankshaft, and the balance 400. The balance mechanism 400 is mainly composed of three large blocks: (1) A right balance device 401 (including a right balance block and a drive gear thereof, etc.) directly driven by the balance mechanism drive gear 302 and installed at the right lower side of the crankshaft 300 of the lower case 1 through a right balance device center shaft 402; (2) A left balance device idler 405 directly driven by the balance mechanism drive gear 302 and mounted above the left of the crankshaft 300 of the upper case 2 through a left balance device idler shaft 406; (3) The left balancer 403 (including a left balancer and a drive gear thereof) is driven by a left balancer idler 405, and is attached to the lower left of the crankshaft 300 of the lower case 1 via a left balancer center shaft 404.

Fig. 5 shows the relative mounting positions of the upper and lower cases 1/2 of the crankshaft with respect to the crankshaft 300 and the balance mechanism 400. The part 101 of the lower case 1 of the crankshaft is a mounting space of the crankshaft 300, 102/103 are mounting spaces of left and right balance devices 403/401, 104 is a mounting hole of a central shaft 402 of the right balance device, and a mounting hole (not shown) of the central shaft of the left balance device is arranged at a symmetrical position of the lower case and 104. The part 201 of the upper case 2 is a space for accommodating a rod piston mechanism (not shown), and the part 202 is a mounting part of a left balance device idler pulley 405 and a central shaft 406 thereof.

FIG. 6 is a front elevational view of the crankcase and gear cover assembly 100 and the transmission assembly 500 according to the present embodiment. C00 is the center line of the crankshaft 300, C01/C02 is the center line of the 1/2 speed reduction shaft of the transmission assembly 500, and C03 is the center line of the final output shaft, where C00 and C01 are at the same height position, C01 and C02 are overlapped (but not limited to being overlapped) in the left-right direction, and the position of C03 is overlapped with the center of gravity position of the engine in the left-right direction.

Fig. 7 and 8 are perspective views showing relative installation relationships between the transmission assembly 500 and the crankcase body and the gear cover assembly 100 in the embodiment, fig. 9 is a bottom view of the upper case 2 of the crankshaft of fig. 8, and fig. 10 is a perspective view showing relative relationships between the transmission assembly 500 and the front cover 3 and the gear cover 4 of the case. The crankcase front cover 3 and the final output shaft gear cover 4 in fig. 7 are partial sectional views taken along section B-B of fig. 6.

As shown in fig. 7, the transmission assembly 500 is driven by a transmission drive gear 301 provided at the front end of the crankshaft 300. The transmission assembly 500 is composed of three stages of gear reduction mechanisms, and the relative installation relationship among the gear reduction mechanisms of each stage, the crankcase body and the gear cover 100 is as follows:

(1) As shown in fig. 7, the first-stage gear reduction mechanism mainly includes a first-stage reduction gear 501, a clutch (not shown, but not limited to, a clutch) integrated therewith, a first-stage gear shaft 502, and a first-stage drive gear 503. The I-stage gear shaft 502 is rotatably connected to the crankcase and the gear cover 100 via the following two bearings: the rear end bearing of the I-stage gear shaft 502 is arranged between the lower box body 1 part 113 (figure 8) and the upper box body 2 part 213 (figure 9); the first stage gear shaft 502 is mounted centrally bearing between the lower housing 1 section 114 (fig. 8) and the upper housing 2 section 214 (fig. 9). The front end portion of the stage i gear shaft 502 is of a cantilever structure for mounting the stage i reduction gear 501 and a clutch (not shown). The first-stage reduction gear 501 and the clutch are housed in a space defined by the lower case 1 portion 111 (fig. 8) and the upper case 2 portion 211 (fig. 9). The first stage reduction drive gear 503 and the second stage reduction gear 504 are placed in a space formed by the lower case 1 portion 112 (fig. 8) and the upper case 2 portion 212 (fig. 8).

(2) The second-stage gear reduction mechanism, as shown in fig. 7, mainly includes a second-stage reduction gear 504, a second-stage gear shaft 505, and a second-stage drive gear 506. The second gear shaft 505 is rotatably connected to the crankcase and gear cover assembly 100 via the following three bearings: the rear end bearing is mounted on the upper case 2 at 215 (fig. 9), the middle bearing is mounted on the case front cover 3 at 31 (fig. 10), and the front end bearing is mounted on the final output shaft gear cover 4 at 41 (fig. 10).

(3) As shown in fig. 10, the third-stage gear reduction mechanism includes a third-stage reduction gear 507, a final output shaft 508, an output shaft flange 509, and the output shaft flange 509 and the final output shaft 508 are of an integrated structure. The final output shaft 508 is rotationally coupled to the crankcase and gear cover assembly 100 via the following two bearings: finally, the rear bearing of the output shaft 508 is mounted at the front cover 3 portion 32 of the case, and finally the front bearing of the output shaft 508 is mounted at the gear cover 4 portion 42.

In summary, the crankcase body and gear cover assembly 100 of the present embodiment uses the upper and lower housing bodies to carry the crankshaft with the gear integrated structure, so that not only the up-and-down motion of the connecting rod piston can be converted into the rotation motion of the crankshaft, but also the two gears integrated with the crankshaft can respectively drive the balance mechanism and the transmission assembly; finally, the miniaturization and the light weight of the inline piston engine are realized, and the attack-weight ratio (power/dead weight) of the aero-engine is improved.

The upper box body and the lower box body bear the balance mechanism, and the balance mechanism is driven by a drive gear of the balance mechanism arranged at the middle rear part of the crankshaft, so that the aim of offsetting the second-order vibration of the in-line piston engine is fulfilled;

the transmission assembly is borne by the upper box body, the lower box body, the front box body cover and the gear cover, the power of the engine is transmitted to the multistage gear speed reducing mechanism by the transmission driving gear arranged at the front end of the crankshaft, the purposes of high speed and high power of the aero-engine are achieved, the miniaturization of the overall dimension of the aero-engine can be realized, meanwhile, the center of the final output shaft of the engine is superposed with the center of gravity of the engine in the left and right directions through the reasonable configuration of the multistage gear speed reducing mechanism, the stability of the engine in the left and right directions is improved, and the carrying performance of the engine is improved.

The above is only a preferred embodiment of the present invention, and not intended to limit the scope of the invention, and it should be appreciated by those skilled in the art that various equivalent substitutions and obvious changes made in the specification and drawings should be included within the scope of the present invention.

Claims (9)

1. The utility model provides a bent axle box and gear cover assembly, its characterized in that, including the bent axle box that is used for bearing bent axle and balance mechanism, install in dismantled and assembled the bent axle box protecgulum of bent axle box one side and install in dismantled and assembled the bent axle box protecgulum for with the output shaft gear cover of the opposite side of bent axle box installation, wherein, the bent axle box protecgulum with the output shaft gear cover bears the transmission assembly jointly, just the space is laid to the connecting rod piston mechanism has still been seted up on the bent axle box.

2. The assembly as claimed in claim 1, wherein the crankcase includes a pair of upper and lower casings having symmetrical structures, a crankshaft mounting space is formed at a corresponding position of the upper and lower casings, a balance mechanism mounting space is formed at both sides of the crankshaft mounting space, the balance mechanism includes left and right balance devices and a left balance device idle pulley, and the lower casing has left and right balance device center shaft mounting holes formed at the balance mechanism mounting space.

3. The crankcase and gear cover assembly according to claim 2, wherein the balance mechanism mounting space includes left and right balance device mounting spaces, the upper crankcase has a left balance device idler mounting space formed at a position above the left balance device mounting space, and the upper crankcase has a left balance device idler mounting space with a mounting hole for a left balance device idler shaft.

4. The crankcase and gear cover assembly according to claim 3, wherein the crankshaft has a balance mechanism drive gear mounted adjacent to the balance mechanism mounting space, the balance mechanism drive gear meshing with a right balance device idler gear and a left balance device idler gear, the left balance device meshing with the left balance device idler gear.

5. The crankcase and gear cover assembly according to claim 1, wherein the transmission assembly is a three stage gear reduction mechanism, the crankcase carries a first stage gear reduction mechanism of the transmission assembly, the crankcase and the crankcase front cover and output shaft gear cover together carry a second stage gear reduction mechanism of the transmission assembly, and the crankcase front cover and the output shaft gear cover carry a third stage gear reduction mechanism of the transmission assembly.

6. The crankcase and gear cover assembly of claim 1, wherein the crankshaft mounts a transmission drive gear adjacent the transmission assembly, the transmission drive gear engaging a first stage gear reduction mechanism, the first stage gear reduction mechanism engaging a second stage gear reduction mechanism, the second stage gear reduction mechanism engaging a third stage gear reduction mechanism.

7. The crankcase and gear cover assembly according to claim 6, wherein the gear shafts of the first stage gear reduction mechanism are mounted in the upper crankcase and the lower crankcase, the gear shafts of the second stage gear reduction mechanism are mounted in the upper crankcase, the front cover of the crankcase, and the output shaft gear cover, and the gear shafts of the third stage gear reduction mechanism are mounted in the front cover of the crankcase and the output shaft gear cover.

8. An engine incorporating a crankcase and a gear cover assembly as claimed in any one of claims 1 to 7.

9. An aircraft equipped with the engine according to claim 8.

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