FR2932238A1 - Gearbox for lawn mower, has transmission mechanism for transmitting movement between driving and driven shafts, and rotating agitation unit rotatably mounted in driving shaft or driven shaft and agitating oil inside gearbox - Google Patents

Abstract

The gearbox (1) has a movement transmission mechanism (5) i.e. clutch mechanism, for transmitting movement between a driving shaft (3) and a driven shaft (4) i.e. driving shaft of wheels of a self-propelled machine, where the gearbox is filled with oil for lubricating pieces of the transmission mechanism. A rotating agitation unit (7) is rotatably mounted in the driving shaft or driven shaft and agitates the oil inside the gearbox.

Description

The present invention generally relates to the motion transmission boxes between a driving shaft and a driven shaft.

The invention more particularly relates to a transmission housing for self-propelled machinery comprising, housed at least partially in said housing, on the one hand, at least one drive shaft and a driven shaft, such as a drive shaft of the wheels. machine, and on the other hand, a mechanism for transmitting motion between driving and driven shafts, such as a clutch mechanism, said housing being at least partially filled with oil to lubricate the parts of the transmission mechanism .

The parts of the motion transmission mechanism cooperating with each other to transmit the movement of the drive shaft to the driven shaft generate a high degree of heat generation by friction. The temperature of the oil contained in the casing then increases rapidly and may exceed a threshold value beyond which the lubricating properties of the oil are degraded. The operation of the transmission case is therefore unreliable.

The object of the invention is to lower the temperature of the oil contained in the transmission housing during operation of the transmission mechanism.

To this end, the invention relates to a transmission housing for self-propelled machinery comprising, housed at least partially in said housing, on the one hand, at least one driving shaft and a driven shaft, such as a drive shaft of vehicle wheels, and secondly, a mechanism for transmitting motion between driving and driven shafts, such as a clutch mechanism, said housing being at least partially filled with oil to lubricate the parts of the mechanism characterized in that the housing comprises at least one rotatable means for agitating the oil inside the housing, said or each rotary stirring means being mounted integral at least in rotation with the driving shaft or the led tree.

Said or each rotary stirring means may be in direct or indirect contact with the driving shaft or the driven shaft. Indeed, said or each rotary stirring means can be rotated, directly or indirectly, by the driving or driven shaft. In particular, said or each rotary stirring means can either be attached to said shaft (leading or driven) or come forming with said shaft, or be carried by another part, such as another shaft, being arranged so as to be rotated by the driving or driven shaft, possibly via a meshing mechanism between the driving or driven shaft and the part carrying the corresponding rotary stirring means. Thanks to the said or each rotary agitation means, the oil is constantly in motion during the operation of the transmission mechanism, which makes it possible to create a circulation of the oil inside the casing, thereby preventing The same volume of oil is subjected locally to a too great increase in temperature.

In addition, by virtue of said at least one rotary stirring means, the oil contained in the casing can be thrown against the walls of said casing whose temperature is below the temperature of the oil near the parts of the transmission mechanism. said parts releasing a large amount of calories. By thermal conduction with the housing walls, the temperature of the projected oil is lowered.

Thus, by virtue of said at least one rotary stirring means according to the invention, during the operation of the transmission mechanism, the oil contained in the casing retains its lubricating properties.

Rotating said one or each rotary stirring means by the driving or driven shaft makes it possible to ensure that when the transmission mechanism is active, the rotary stirring means is also active to limit the increase. the temperature of the oil inside the housing. According to an advantageous characteristic of the invention, said or each rotary stirring means has at least one part offset relative to its axis of rotation, so that the oil is agitated by said or each deported part during the rotation. stirring means.

According to an advantageous characteristic of the invention, said or each rotary stirring means is formed by a plurality of blades disposed radially around the driving or driven shaft.

The use of a plurality of blades makes it possible to increase the efficiency of the or each rotary stirring means.

According to an advantageous characteristic of the invention, said or each rotary stirring means is formed by a bladed wheel whose hub is secured in rotation to the driven or driving shaft. According to an advantageous characteristic of the invention, said or each rotary stirring means has the shape of a helix.

According to an advantageous characteristic of the invention, the transmission mechanism is a cone clutch mechanism, arranged coaxial with the driven shaft, the or at least one of the rotating means (s) stirring being carried by said driven shaft.

The housing according to the invention is particularly advantageous when the transmission mechanism is a cone clutch mechanism since such a mechanism releases, due to friction forces, between the cones a very large amount of heat during its operation. .

According to a particular embodiment of the invention, the cone clutch mechanism comprises two male cones mounted on the driven shaft, integral in rotation therewith, and two female cones mounted integral in rotation with the shaft. leading, the male and female cones of each pair of cones being adapted to cooperate by approximation for the passage in the engaged position.

According to an advantageous characteristic of the invention, the or each rotary stirring means is secured in rotation with the driven shaft or driving it equips with a pin. The use of a pin makes it easy and simple to join the rotary stirring means to the corresponding shaft.

According to a particular embodiment of the invention, in which the housing, of generally parallelepipedal shape, is of the type of which the driven shaft passes through opposite side walls of the housing, the housing is characterized in that said driven shaft is equipped two rotary oil agitation means disposed near said opposite side walls traversed.

The use of two rotary stirring means arranged near opposite side walls makes it possible to improve the circulation of the oil along the side walls of the casing, which favors the heat exchange between the oil and the walls of the casing. housing and thus limits the temperature increase of the oil.

The invention also relates to a self-propelled mobile vehicle, preferably with a walking conductor, such as a lawn mower, characterized in that it is equipped with a transmission housing as described above.

The invention will be better understood on reading the following description of exemplary embodiments, with reference to the appended drawings, in which: FIG. 1 is a perspective view of a rotary stirring means according to the invention; FIG. 2 is a front view of said rotary stirring means of FIG. 1; FIG. 3 is a side view of the rotary stirring means of FIG. 1; FIG. 4 is a perspective view of a portion of the housing according to the invention cut along a plane passing through the axes of the driven and driving shafts; - Figure 5 is an axial sectional view of the housing according to the invention; - Figure 6 shows a schematic overview of a rolling machine, in this case a lawn mower, equipped with a transmission housing according to the invention.

The transmission housing according to the invention is more particularly intended to be applied to self-propelled mobile vehicles in particular with a walking conductor.

Figure 6 shows the application of the transmission housing according to the invention to a lawn mower. This lawn mower comprises a chassis 2, the rear wheels of this chassis being shown at 30 in Figure 1. A lo motor 31 equips the machine. The motor output shaft 32 carries, on the one hand, a cutting blade 33, and on the other hand, a driving pulley 38 connected via a belt 34 to a driven pulley 35. This driven pulley 35 is itself mounted on a motor input shaft 3 intended to be housed at least partially in a transmission housing 1. The transmission housing 1 comprises, housed at least partially in said housing, on the one hand, a drive shaft, formed by the motor input shaft 3 and a driven shaft 4, here the wheel drive shaft. 30 of the machine, and secondly, a mechanism 5 of motion transmission between the shafts 3, 4 leading 20 and led, such as a clutch mechanism. Said housing 1 is at least partially filled with oil 6 to lubricate the parts of the transmission mechanism 5.

In a manner that is characteristic of the invention, the casing comprises at least one rotating means 7 for agitating the oil inside the casing 1, said or each rotary stirring means 7 being integral at least in rotation, directly or indirectly, the driving shaft 3 or the driven shaft 4. In the example illustrated in the figures, there are provided two rotary stirring means 7 carried by the shaft 4 and secured in rotation thereof . The casing is generally parallelepipedal in shape. As illustrated in FIGS. 4 to 6, the driven shaft 4, formed of a single shaft or two half-shafts, passes through opposite side walls 1A, 1C of the housing to drive on one side a wheel of the machine and on the other side another wheel of the machine. The rotary stirring means 7 are threaded onto said driven shaft 4 and arranged near said opposite side walls 1A 1C.

Preferably, each rotary stirring means 7 is formed by a plurality of blades 7A or blades arranged radially around the shaft 4 they equip. In the example illustrated in the figures, each rotary stirring means 7 is formed by a bladed wheel so: the hub 7B is secured in rotation to the shaft 4 that it equips. The blades 7A are twisted so as to affect the shape of a helix. Alternatively, it could be provided that the blades or blades are formed with the shaft they equip are made in one piece with the latter.

Furthermore, as illustrated in FIGS. 4 and 5, said driven shaft 4 extends parallel to the bottom wall 1A of the housing, which allows the stirring means 7 to effectively agitate the oil which accumulates by gravity in the bowl formed by the bottom wall when the housing is partially filled with oil. The rotationally driven blades 7A also allow the oil to be projected against the side walls 1C, 1D, 1E of the housing and the top wall 1B of the housing.

In the example illustrated in the figures, said transmission mechanism is a cone clutch mechanism.

As illustrated in FIGS. 4 and 5, this cone clutch comprises a tangential gear 8 driven by an endless screw forming said driving shaft 3. This toothed wheel 8 is mounted coaxially with the driven shaft 4, here the drive output shaft 30 of the forward wheels of the self-propelled crane. This toothed wheel 8 is securable to the shaft 4 driven by means of two male friction cones 9, 10 arranged coaxial with the axial bore of the toothed wheel 8. For mounting on the driven shaft 4, the 9, 10 male friction cones are hollowed out centrally.

The toothed wheel 8 has a bore which internally comprises two friction surfaces 11, 12 conical, also called conical bearings. Conical bearings are also called female cones. As illustrated in FIGS. 4 and 5, the toothed wheel 8 thus forms two female cones 11, 12.

Each male cone 9, 10 is adapted to cooperate with the female cone 11, 12 corresponding by bringing said cones 9, 11 and 10, 12 together for the passage from a disengaged position to an engaged position. As detailed below, the cooperation of the cones 9, 10 of male friction with the cones 11, 12 females associated with the toothed wheel 8 is carried out using a control member 13.

The cones 9, 10 of male friction are made integral in rotation with the driven shaft 4 by means of pins 18.

The control device of the cone clutch mechanism is formed of a member 13 movable angularly around an axis substantially perpendicular to the axis of the rotated shaft 4 to ensure the tightening or loosening of the cones 9, 10 male friction and cones 11, 12 corresponding female friction. The angular displacement of the control member 13, also called fork, is controlled by means of a clutch lever biased into the disengaged position by a spring.

The operation of the transmission housing is as follows: during an angular displacement of the control member 13 in the direction of a thrust towards the male friction cones 9, 10, the cones 9, 10 are displaced. inside the cones 11, 12 females. The permanent rotational movement of the toothed wheel 8 driven by the worm is then transmitted via the connection female cones - male cones to the driven shaft 4 which causes a drive of the machine advancement wheels. 30 self-propelled.

The rotation of the driven shaft 4 also drives the stirring means 7 carried by said shaft 4 in rotation. Thus, the oil contained in the housing is agitated by the blades 7A of said stirring means 7. such agitation of the oil causes a movement of the latter inside the housing which avoids a local increase in the temperature of the oil near the parts of the clutch mechanism. In addition, thanks to the stirring means 7, the oil, located near the parts of the clutch mechanism, is circulated and / or sprayed against the walls of the lower temperature housing, which allows for thermal transfer between the oil and the housing walls to lower the temperature of the oil so that it retains its lubricating properties. The operation of the gearbox is therefore reliable.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind. Alternatively, it can be provided that only the driving shaft is equipped with at least one rotary stirring means or that each shaft, driven and driving, is equipped with at least one rotary stirring means.

Claims (10)

REVENDICATIONS1. Transmission housing (1) for self-propelled machinery (2) comprising, housed at least partially in said housing, on the one hand, at least one shaft (3) leading s and a shaft (4) driven, such as a shaft d driving the wheels of the machine, and secondly, a mechanism (5) for transmitting motion between the driving and driven shafts (3, 4), such as a clutch mechanism, said housing (1) being at least partially filled with oil (6) for lubricating the parts of the transmission mechanism (5), characterized in that the casing (1) comprises at least one rotary stirring means (7) for the oil to the interior of the housing, said or each rotary stirring means (7) being mounted integral at least in rotation with the driving shaft (3) or the driven shaft (4). 15 2. Transmission housing (1) according to claim 1, characterized in that said or each rotary stirring means (7) has at least one remote portion (7A) relative to its axis of rotation, so that the oil is agitated by said or each remote part (7A) during the rotation of the stirring means. 20 Transmission housing (1) according to one of the preceding claims, characterized in that said or each rotary stirring means (7) is formed by a plurality of blades (7A) arranged radially around the driving shaft. (3) or led (4). 4. transmission housing (1) according to one of the preceding claims, characterized in that said or each rotary stirring means (7) is formed by a blade wheel whose hub (7B) is secured in rotation to the tree (4) that he equips. 30 Transmission housing (1) transmission (1) according to one of the preceding claims, characterized in that said or each rotary stirring means (7) affects the shape of a helix. 9 25i0 Transmission housing (1) according to one of the preceding claims, characterized in that the transmission mechanism (5) is a cone clutch mechanism arranged coaxially with the driven shaft (4), or at least one of the rotating means (s) stirring (7) being carried (s) by said shaft (4) led. 7. transmission housing (1) according to the preceding claim, characterized in that the cone clutch mechanism comprises two male cones (9, 10) mounted on the shaft (4) led, integral in rotation thereof , and two female cones (11, 12) mounted integral in rotation with the driving shaft (3), the male and female cones of each pair of cones being able to cooperate by bringing together for the passage in the engaged position. Transmission housing (1) according to one of the preceding claims, characterized in that the or each rotary stirring means (7) is secured in rotation with the shaft (4) which it equips with the using a pin (18). 9. Transmission housing (1) according to one of the preceding claims, of parallelepipedal general shape, of the type of which the shaft (4) driven through opposite side walls (1A, 1C) of the housing, characterized in that said driven shaft (4) is equipped with two rotating oil stirring means (7, 8) arranged near said opposite side walls (1A, 1C). 10. Self-propelled traveling vehicle, preferably with a walking conductor, such as a lawn mower, characterized in that it is equipped with a transmission casing (1) according to one of the preceding claims.