Patent Description:
To start an engine, such as a diesel engine for a work machine or other vehicle, it is typically necessary to provide mechanical input to start rotation of a crankshaft so that pistons connected thereto will reciprocate. This can require significant torque. It is known to use an electric starter motor powered by the vehicle's battery to initiate rotation of the crankshaft during starting.

Once the engine is started, electrical components of a vehicle can be powered using engine power by using an electric machine to generate electrical power. The vehicle's battery can be charged by using the electric machine as a generator. <CIT> and <CIT> show two gearbox arrangements with brake, free wheel clutch and planetary gear having an axially movable ring gear.

It is known to provide integrated starter/generator devices, however, these are often inconveniently long and interfere with positioning of equipment.

It is desirable to provide an integrated starter/generator. It is further desirable to provide an integrated starter/generator that is compact.

In accordance with an aspect of the present invention, a gearbox arrangement of an electric machine of an engine comprises a planetary gear arrangement configured to receive rotational input from the electric machine and from the engine and to mechanically couple the electric machine and the engine in first and second power flow directions, the planetary gear set comprising a ring gear, a ring brake, a free-wheel clutch attachable to a fixed structure and the ring brake, the free-wheel clutch permitting rotation of the ring brake in a first direction and preventing rotation of the ring brake in an opposite second direction, and means for moving the ring gear between a first position in which the ring gear is non-rotatably engaged with the ring brake and a second position in which the ring gear is non-rotatably engaged with the carrier.

In accordance with another aspect of the present invention, an engine starter and power generator device comprises an engine, an electric machine, and a gearbox arrangement. The gearbox comprises a planetary gear arrangement configured to receive rotational input from the electric machine and from the engine and to mechanically couple the electric machine and the engine in first and second power flow directions, the planetary gear set comprising a ring gear, a ring brake, a free-wheel clutch attached to a fixed structure and the ring brake, the free-wheel clutch permitting rotation of the ring brake in a first direction and preventing rotation of the ring brake in an opposite second direction, and means for moving the ring gear between a first position in which the ring gear is non-rotatably engaged with the ring brake and a second position in which the ring gear is non-rotatably engaged with the carrier.

The features and advantages of the present invention are well understood by reading the following detailed description in conjunction with the drawings in which like numerals indicate similar elements and in which:.

An engine starter and power generator device <NUM> according to an aspect of the present invention is shown in <FIG> and <FIG> and includes an engine <NUM>, an electric machine <NUM>, and a gearbox arrangement <NUM>. The engine starter and power generator device <NUM> can be associated with a vehicle <NUM>, such as a work vehicle or other conventional vehicle, shown schematically in the figures.

The gearbox arrangement <NUM> comprises a planetary gear arrangement <NUM> configured to receive rotational input from the electric machine <NUM> and from the engine <NUM> and to mechanically couple the electric machine and the engine in first and second power flow directions (<FIG> and <FIG>, respectively). The planetary gear arrangement <NUM> comprises, inter alia, a ring gear <NUM> and a carrier <NUM>. As seen in <FIG>, the first power flow direction is from the electric machine <NUM> to the engine <NUM> and, as seen in <FIG>, the second power flow direction is from the engine <NUM> to the electric machine <NUM>.

The gearbox arrangement <NUM> also comprises a ring brake <NUM>, a free-wheel clutch <NUM> attached to a fixed structure, such as a housing <NUM> of the engine, and the ring brake. The free-wheel clutch <NUM> permits rotation of the ring brake <NUM> in a first direction and prevents rotation of the ring brake in an opposite second direction. The gearbox arrangement also comprises means <NUM> for moving the ring gear <NUM> between a first position (<FIG>) in which the ring gear <NUM> is non-rotatably engaged with the ring brake <NUM> and a second position (<FIG>) in which the ring gear is non-rotatably engaged with the carrier <NUM>.

The planetary gear arrangement <NUM> can be configured to effect a first gear ratio in the first power flow direction and a different, second gear ratio in the second power flow direction. Ordinarily, the first gear ratio is greater than the second gear ratio.

The ring gear moving means <NUM> can comprise a shift fork <NUM>. As seen, for example, in <FIG> and <FIG>, a spring arrangement <NUM> such as a Belleville spring pack can be configured to urge the shift fork to a first shift fork position so that the ring gear is moved to the first position (as seen in <FIG>). Means <NUM> such as an air piston 47a in a cylinder 47b (fluid connections not shown) can be provided for moving the shift fork <NUM> to a second shift fork position so that the ring gear is moved to the second position as seen in <FIG> against a force of the spring arrangement <NUM>.

One or more plunger shafts <NUM> can be provided to extend between the air piston 47a and the spring arrangement <NUM> so that movement of the air piston compresses the spring arrangement or relieves compression of the spring arrangement The means <NUM> for moving the shift fork <NUM> can comprise any suitable means for moving the shift fork, such as the air piston arrangement noted, a hydraulic piston arrangement, a solenoid arrangement, a cam arrangement, or a manually operated arrangement.

While it is presently preferred that the means <NUM> for moving the shift fork <NUM> moves the shift fork in one direction (to the position shown in <FIG>) against the force of the spring arrangement <NUM> which urges the shift fork in an opposite direction (to the position shown in <FIG>), the means for moving the shift fork may be configured to move the shift fork back and forth between the positions shown in <FIG> and <FIG> as desired, such as by providing a valve to permit fluid flow in different directions in and out of the cylinder for pneumatic and hydraulic arrangements, or having a solenoid move the shift fork to one position when activated and to the other position when deactivated.

The planetary gear arrangement <NUM> ordinarily comprises a planetary output gear <NUM> that is connected to a crankshaft <NUM> of the engine <NUM> via a configuration that can include an idler gear <NUM> and an engine bull gear <NUM>. The spring arrangement <NUM> can be disposed in a shaft <NUM> of the idler gear <NUM>, typically supported on the shaft by bearings <NUM>, which can assist in reducing the length of the engine starter and power generator device <NUM>.

The shift fork <NUM> is ordinarily supported by a shift rail <NUM>. The shift rail <NUM> can include an internally threaded portion <NUM> engaged with a cap screw <NUM> to provide a clamping force to a bearing subassembly <NUM> on the idler gear shaft <NUM>, such as by urging a flange 55a of the idler gear shaft against the bearing subassembly to retain it in position between the flange and another structure, such as a fixed structure such as the engine housing <NUM>.

The planetary gear arrangement <NUM> typically comprises a sun gear <NUM>, the carrier <NUM>, and the planetary output gear <NUM>. The carrier <NUM> can be clamped to the planetary output gear <NUM> via a bolt <NUM> and a planetary carrier clamp washer <NUM>. The planetary carrier clamp washer <NUM> can be arranged to form a thrust surface for the sun gear <NUM>. A threaded end <NUM> of the bolt <NUM> can mate with internal threads <NUM> in a shaft <NUM> of the planetary output gear <NUM> and a head <NUM> of the bolt can be disposed in a recess <NUM> in the sun gear.

In operation, such as during starting of the engine <NUM> by driving the crankshaft <NUM> using the electric machine <NUM>, i.e., the first power flow direction, the ring gear moving means <NUM> moves the ring gear <NUM> to the first position shown in <FIG> in which the ring gear is non-rotatably engaged with the ring brake <NUM> by any suitable arrangement that permits engagement and disengagement, such as via frictional contact or a spline arrangement. An input/output shaft <NUM> of the electric machine <NUM> is non-rotatably attached to the sun gear <NUM>, such as by being clamped in a shaft <NUM> of the sun gear.

In such an arrangement, when the input/output shaft <NUM> is driven by the electric machine <NUM> and turns in a first rotational direction, the sun gear <NUM> turns at the same speed and in the same direction as the input/output shaft <NUM>. One or more planet gears <NUM> that engage with the sun gear <NUM> and the stationary ring gear <NUM> are turned in a second rotational direction around axes of the planet gears and move in the second rotational direction around the sun gear at a lower rotational speed than the sun gear and the input/output shaft <NUM> of the electric machine. As the planet gears <NUM> move in the second rotational direction around the sun gear <NUM> at the lower rotational speed, the carrier <NUM> and the planetary output gear <NUM> are also moved around the sun gear in the second rotational direction at the lower rotational speed. The planetary output gear <NUM>, in turn, turns the idler gear <NUM>, which turns the bull gear <NUM>, which turns the crankshaft <NUM>.

The free-wheel clutch <NUM> paired with the planetary gear arrangement <NUM> allows the engine <NUM> to have a steep gear ratio at cranking to facilitate starting, but allows the planetary components to free wheel when the engine begins to fire and accelerate. When the engine <NUM> starts and the crankshaft <NUM> starts turning at a speed that would drive the sun gear <NUM> and the input/output shaft <NUM> at a speed greater than the speed at which the electric machine <NUM> drives the input/output shaft, the free-wheel clutch <NUM> permits freewheeling of the ring brake <NUM> and the ring gear <NUM> to avoid causing the electric machine to turn too fast.

It is possible to operate the engine starter and power generator device <NUM> in a manner so that mechanical component rotating speeds, such as the speed of the ring gear <NUM> and the free-wheel clutch, can be limited. This may be desirable when, for example, a free-wheel sprag clutch has a speed limit. As seen in the graph at <FIG>, during a cranking stage, the speed A of the input/output shaft <NUM> and the sun gear <NUM> increases from zero to a speed S, which may be the synchronous speed at which the ring gear <NUM> and the carrier <NUM> can engage. At the same time, the speed B of the ring gear <NUM> remains zero, the speed C of the carrier <NUM> and the speed D of the engine <NUM> increase from zero to levels depending upon gear ratios of the gears between the carrier and the crankshaft <NUM>. After cranking, as the engine <NUM> accelerates and the speed D of the engine increases, the speed C of the carrier <NUM> increases as well. The ring gear <NUM> disengages from the ring brake <NUM>. The rotation of the input/output shaft <NUM> and the sun gear <NUM> about their axes causes rotation of the planet gears <NUM> about their axes which, in turn, causes rotation of the ring gear <NUM> in a direction opposite the direction of rotation of the input/output shaft and the sun gear; while rotation of the carrier <NUM> about its axis causes the planet gears <NUM> to turn about the axis of the input/output shaft and the sun gear which, in turn, causes the ring gear to rotate in the same direction as the input/output shaft and the sun gear. If the speed A of the input/output shaft <NUM> and the sun gear <NUM> remains at the speed S, then, when the ring gear disengages from the ring brake <NUM>, the speed B of the ring gear <NUM> may increase substantially from zero as seen in <FIG>. When the speed D of the engine <NUM> decreases to an idle speed, the speeds B and C of the ring gear <NUM> and the carrier <NUM>, respectively, can decrease to correspond to the synchronous speed S and the ring gear and the carrier can engage as shown in <FIG>.

As seen in the graph at <FIG>, during acceleration of the engine, as the speed D of the engine increases, the speed A of the input/output shaft <NUM> and the sun gear <NUM> can be increased. In this way, the speed B of the ring gear <NUM> can be kept from exceeding a predetermined speed, such as the synchronous speed S. In this way, it is possible to avoid damage to components such as the freewheel clutch <NUM> by rotation of the ring gear <NUM> at excessive speeds.

When the electric machine <NUM> functions as a generator and power flows from the engine <NUM> to the electric machine, i.e. the second power flow direction, the ring gear moving means <NUM> moves the ring gear <NUM> to the second position shown in <FIG> in which the ring gear <NUM> is disengaged from the ring brake <NUM> and engaged with the carrier <NUM> by any suitable arrangement, such as via frictional contact or a spline arrangement. In this position, the planetary output gear <NUM>, the carrier <NUM>, the ring gear <NUM>, the sun gear <NUM>, and the input/output shaft <NUM> of the electric machine <NUM> rotate at the same rotational speed S. When the engine <NUM> drives the planetary output gear <NUM>, via the crankshaft <NUM>, the bull gear <NUM>, and the idler gear <NUM>, in the second rotational direction, the turning of the input/output shaft <NUM> can be used to generate electricity that can be used for electrical components on the vehicle (e.g., pumps, air conditioning, other engine components (not shown)) or stored in, e.g., a battery (not shown).

In the present application, the use of terms such as "including" is open-ended and is intended to have the same meaning as terms such as "comprising" and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as "can" or "may" is intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

Claim 1:
A gearbox arrangement (<NUM>) of an electric machine (<NUM>) of an engine, comprising:
a planetary gear arrangement (<NUM>) configured to receive rotational input from the electric machine (<NUM>) and from the engine (<NUM>) and to mechanically couple the electric machine (<NUM>) and the engine (<NUM>) in first and second power flow directions, the planetary gear arrangement (<NUM>) comprising a ring gear (<NUM>);
a ring brake (<NUM>);
a free-wheel clutch (<NUM>) attachable to a fixed structure and the ring brake (<NUM>), the free-wheel clutch (<NUM>) permitting rotation of the ring brake (<NUM>) in a first direction and preventing rotation of the ring brake (<NUM>) in an opposite second direction; and
means for moving the ring gear (<NUM>) between a first position in which the ring gear (<NUM>) is non-rotatably engaged with the ring brake (<NUM>) and a second position in which the ring gear (<NUM>) is non-rotatably engaged with acarrier (<NUM>); the ring gear (<NUM>) moving means comprises a shift fork (<NUM>),
characterized in that the gearbox arrangement (<NUM>) further comprises:
a spring arrangement (<NUM>) configured to urge the shift fork (<NUM>) to the first position and means for moving the shift fork (<NUM>) to the second position against a force of the spring arrangement (<NUM>);
wherein the planetary gear arrangement (<NUM>) comprises a planetary output gear (<NUM>), the planetary output gear (<NUM>) being connectable to a crankshaft (<NUM>) of the engine (<NUM>) via an idler gear (<NUM>), the spring arrangement (<NUM>) being disposed in a shaft (<NUM>) of the idler gear (<NUM>).