Cooling arrangement for cooling a gearbox

A cooling arrangement (1) is provided for cooling a gearbox (2) that has a housing (20) on which at least one temperature-critical component is mounted. The cooling arrangement has a gearbox-ventilating device (4) arranged fixedly on the body to adjoin the gearbox (2) and configured to supply the gearbox (2) with cooling air. The gearbox-ventilating device (4) has a first air duct (6) with an air inlet opening (60), via which cooling air can flow into the first air duct (6), and an air outlet opening (62) from which cooling air can flow out of the first air duct (6). A cooling air-channeling means (7) is connected to the first air duct (6) and designed to guide the cooling air flowing out of the air outlet opening (62) and directly onto the temperature-critical component of the gearbox (2).

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 to German Patent Appl. No. 10 2017 110 921.8 filed on May 19, 2017, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

Field of the Invention

The invention relates to a cooling arrangement for cooling a gearbox. The gearbox has a housing on which at least one temperature-critical component is mounted. The cooling arrangement includes a gearbox-ventilating device that is arranged fixedly on the body so as to adjoin the gearbox and that is configured to supply the gearbox with cooling air.

Description of the Related Art

Cooling arrangements for cooling a gearbox are known in the prior art. The cooling air flows through at least one air inlet into the cooling arrangement and can be guided to certain regions of the gearbox, for example by one or more air-channeling ducts and/or by blades or other air deflection means.

DE 103 08 084 B4 discloses a cooling arrangement for cooling a gearbox, in which a cladding part in a front region of a housing of the gearbox has air inlets for cooling purposes. The inlets are wide to produce a slowly flowing air movement.

Gearboxes known frequently have one or more temperature-critical components. These temperature-critical components include, for example, a control device of the gearbox. The control device can be mounted on an outer side of a housing of the gearbox and is exposed to relatively high thermal loading during operation. The control device must be cooled to function properly. Improper cooling could cause the control device to overheats both during driving and with the vehicle stationary.

The object of the invention is to provide a cooling arrangement for cooling a gearbox that makes it possible to provide efficient cooling of a temperature-critical component, in particular a control device, of the gearbox.

SUMMARY

The invention relates to a gearbox ventilating device that has a first air duct and a cooling air-channeling means. The first air duct has an air inlet opening for receiving a flow of cooling air into the first air duct and an air outlet opening from which cooling air can flow out of the first air duct. The cooling air-channeling means is connected to the first air duct and is designed to guide the cooling air flowing from the air outlet opening onto the temperature-critical component of the gearbox. This measure ensures effective direct cooling of the temperature-critical component of the gearbox.

The cooling air-channeling means may extend around the temperature-critical component of the gearbox at least in certain portions and may at least partially enclose the component to allow efficient cooling of the temperature critical component. As a result, the cooling air can be guided directly at least in certain regions onto the temperature-critical component of the gearbox.

The cooling air-channeling means may completely enclose the temperature critical component to ensure a still more effective direct cooling of the temperature-critical component of the gearbox. Completely enclosing the temperature-critical component with the air-channeling means avoids a stationary heating-up. The cooling air-channeling means can be formed in a substantially snorkel-like manner.

The cooling air-channeling means may have a first end and that the first air duct may have a free end in which the air outlet opening is formed. The first end of the cooling air-channeling means and the free end of the first air duct are formed so that, in the desired mounting position, the first air duct extends into the cooling air-channeling means. In other words, the free end of the first air duct engages into the first end of the cooling air-channeling means to achieve a reliable flow connection between the air duct and the cooling air-channeling means.

The gearbox-ventilating device can be mounted fixedly to the body on an underfloor of the motor vehicle to retain the gearbox-ventilating device securely on the body of the motor vehicle. Thus, the cooling air advantageously is supplied to the gearbox-ventilating device from the direction of the underfloor of the motor vehicle.

The cooling air-channeling means may be mounted fixedly on the housing of the gearbox to ensure that the cooling air-channeling means is retained securely.

The cooling air-channeling means may be mounted fixedly to the gearbox, and the gearbox-ventilating device may be mounted fixedly to the body on the underfloor of the motor vehicle to allow relative movements of the cooling air-channeling means relative to the first air duct. The free end of the first air duct may taper in the direction of the air outlet opening. Thus, there remains sufficient play for relative movements of the cooling air-channeling means relative to the free end of the first air duct that engages therein. Moreover, this tapering also produces a nozzle effect that has a positive effect on the flow behavior of the cooling air when flow passes through the first air duct.

The gearbox-ventilating device may have a second air duct with an air inlet opening, through which cooling air can flow into the second air duct, and an air outlet opening, through which the cooling air can flow out of the second air duct.

The second air duct can be adjacent to the first air duct. The cooling air flow of the second air duct can be directed for example onto an underside of the gearbox to cool this region.

The second air duct can taper in the direction of its air outlet opening. This tapering brings about a nozzle effect that has a positive effect on the flow behavior of the cooling air while flow passes through the second air duct.

Further features and advantages of the invention will become clearer from the following description of an embodiment with reference to the appended drawings.

DETAILED DESCRIPTION

FIG. 1shows a part of a gearbox2that is referred to as a “hang-on gearbox” and that is used in motor vehicles with a clutch-controlled all-wheel drive in which one of the axles of the motor vehicle is driven permanently and the other axle is driven only as required. The gearbox2has a housing20, and a control device3that controls the operation of the gearbox2is mounted on the housing20. The control device3is a temperature-critical component of the gearbox2and must be cooled to avoid overheating during driving of the motor vehicle and when the vehicle stationary. Ineffective cooling can lead to a disruption of the operation or irreversible damage to the control device3.

FIGS. 2 and 3illustrate a cooling arrangement1to allow effective cooling of the control device3. The cooling arrangement1has a gearbox-ventilating device4that can be mounted fixedly to the body on an underfloor10of the motor vehicle. The gearbox-ventilating device4comprises an air inlet5that can supply cooling air from the direction of the underfloor10of the motor vehicle for cooling the gearbox2.

The gearbox-ventilating device4further comprises a first air duct6with an air inlet opening60that can be seen in the bottom view ofFIG. 5. Cooling air can flow from the direction of the underfloor of the motor vehicle into the first air duct6via this air inlet opening60. The first air duct6further has a free end61with an air outlet opening62, from which cooling air can flow out of the first air duct6.

The cooling arrangement1further has a cooling air-channeling means7for cooling the control device3mounted on the housing20of the gearbox2. In the present case, the cooling air-channeling means7is designed to be substantially snorkel-like. The cooling air-channeling means7has a first end70that is to be placed on the first air duct6so that the first air duct60extends into the cooling air-channeling means7and engages therein. This ensures a secure flow connection so that the cooling air can flow out of the air outlet opening62of the first air duct6into the cooling air-channeling means7.

The cooling air-channeling means7extends around the control device3mounted on the housing20of the gearbox2and completely encloses the control device3. The control device3can be cooled directly and thus is protected from overheating by the cooling air that flows through the cooling air-channeling means7and flows out toward the control device3. The air-channeling means7is designed and arranged to completely enclose the control device3, thereby ensuring in a particularly advantageous manner that the gearbox2can be cooled effectively during the driving operation of the motor vehicle and also with the vehicle stationary. As a result, a stationary overheating of the control device3can be prevented.

The cooling air-channeling means7further has a second end71that is mounted fixedly on the housing20of the gearbox2. This fixed mounting to the gearbox means that the cooling air-channeling means7has three degrees of freedom for relative movements with respect to the gearbox-ventilating device4fixed to the body in three mutually orthogonal spatial directions (i.e. in the longitudinal direction, in the transverse direction and in the vertical direction) if the gearbox2moves in the corresponding directions. To allow these relative movements of the cooling air-channeling means7fixed to the gearbox relative to the gearbox-ventilating device4fixed to the body, the free end61of the first air duct6tapers in the direction of the air outlet opening62. Thus, there remains sufficient play for relative movements of the cooling air-channeling means7relative to the free end61of the first air duct6that engages therein. Moreover, this tapering makes available a nozzle effect that has an advantageous effect on the flow behavior of the cooling air when flow passes through the first air duct6.

To further improve the cooling of the gearbox2, the gearbox-ventilating device4has a second air duct8that comprises an air inlet opening80, through which cooling air can flow into the second air duct8from the direction of the underfloor of the motor vehicle, and an air outlet opening81, through which the cooling air can flow out of the second air duct8. The gearbox2can be cooled on an underside directed toward the underfloor of the motor vehicle by the cooling air that flows through the second air duct8. In this embodiment, the second air duct8tapers in the direction of its air outlet opening81to produce a nozzle effect with a positive effect on the flow behavior of the cooling air when flow passes through the second air duct8. In the present case, a separating web82subdivides the air outlet opening81into two regions. The air inlet5that communicates with the housing of the gearbox constitutes a third air inlet opening.

The cooling arrangement1provides effective cooling of at least one temperature-critical component of the gearbox2, which in the present case is a control device3. The control device3is surrounded completely by the cooling air-channeling means7that can be supplied with cooling air from the direction of the underfloor of the motor vehicle by means of the specially formed first air duct6.