Patent Application
20110011206
This invention generally relates to a parking brake rotor that has been integrated into a driveline yoke.
Parking brakes are often difficult to package along vehicle drivelines. A typical driveline is comprised of an engine and transmission that provide driving input to a transfer case. The transfer case typically has a first driving output to drive a rear differential of a rear axle and a second driving output to selectively drive a front differential.
It is often difficult to mount the parking to the front and rear differentials due to interference with other vehicle components. Similarly, it is difficult to mount the parking brake near the transfer case due to limited packaging restraints. Additionally, installing the parking brake at locations along the driveline can adversely affect driveline angles.
A driveline yoke is integrally formed as one-piece with a brake rotor. Thus, the yoke and brake rotor comprise a single-piece, unitary, monolithic structure having a continuous, uninterrupted surface.
In one example, the brake rotor and yoke are formed as a single-piece component using a casting process.
In one example, at least one caliper includes a friction element that selectively engages the brake rotor. The friction element engages a braking surface on the brake rotor in response to a parking brake request.
In one example, the yoke is coupled to an output of a transfer case and the at least one caliper is mounted to a housing of the transfer case.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
The front output shaft 22 is either permanently coupled to, or can be selectively coupled to, a front drive axle 26. The front drive axle 26 is typically a steer axle; however, other types of axles could also be used for the front axle. The front drive axle 26 includes a front differential 28 that drives a pair of front axle shafts 30, which in turn drive a pair of front wheels 32.
The rear output shaft 24 drives a rear drive axle 34, which can be a single drive axle as shown, or could comprise a tandem axle or another type of axle configuration. The rear drive axle 34 includes a rear differential 36 that drives a pair of rear axle shafts 38, which in turn drive a pair of rear wheels 40.
A first driveshaft 42 connects the front output shaft 22 to the front drive axle 26 and a second driveshaft 44 connects the rear output shaft 24 to the rear drive axle 34. Typically, connections between shafts and the various drivetrain components are provided by yoke assemblies.
An example of the first yoke 54 is shown in
In the example shown in
The shaft body 60 at yoke end 62 includes a splined connection interface 70 for connection to the front output shaft 22 of the transfer case 18; however, other types of connection interfaces could also be used. At a position axially between the splined connection interface 70 and the yoke connection interface 64, the first yoke 54 includes a rotor 72 that is integrally formed as one-piece with the first yoke 64. Thus, the first yoke 54 and rotor 72 comprise a unitary, monolithic, single piece component having a continuous, uninterrupted surface.
The rotor 72 defines a braking surface 74 that is selectively engaged by at least one caliper 76. In the example shown, the caliper 76 is mounted to the housing 50 of the transfer case 18. However, the caliper 76 could be mounted to other non-rotating structures, such as a vehicle frame for example. The caliper 76 selectively engages the braking surface 74 in response to a parking brake request.
The parking brake request is a signal that is typically generated by a vehicle operator. The signal can be any type of signal, and movement of the caliper 76 to engage the rotor 72 can be initiated hydraulically, pneumatically, or electrically for example.
In the example shown in
The shaft body 60 is defined by a first diameter D1 at the yoke end 62 and is defined by a second diameter D2 at the yoke end 66 that is greater than the first diameter D1. The rotor 72 is defined by a third diameter D3 that is greater than the second diameter. Transition surfaces of varying diameters extend from the shaft body 60 to the rotor 72, and from the rotor 72, to the yoke connection interface 64.
By integrally forming the rotor 72 with the yoke 54 a compact parking brake configuration is provided that is easily incorporated into a vehicle driveline. As the yoke 54 has a splined connection interface 70, the rotor 72 is easily installed without requiring any fastening elements. Also, because fasteners are not required for rotor attachment, the brake surface area is maximized without having to increase the rotor diameter.
Further, in comparison to prior parking brakes, there are fewer components which reduces cost and weight. Also, because the number of components are reduced, the balancing of the brake is more easily accomplished. In prior designs, multiple brake components had to be individually balanced. With the configuration described above, only one component needs to be balanced, i.e. only the yoke-rotor needs to be balanced.
Finally, the integrated rotor and yoke does not adversely affect driveshaft lengths, which in turn preserves proper driveshaft angles. Specifically, the compact arrangement maintains driveline angles at less than six degrees.
It should be understood that the drivetrain 10 shown in
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
