Power plants – Pressure fluid source and motor – Having a mechanical clutch or brake device in the power train
Reexamination Certificate
2000-07-25
2003-04-08
Look, Edward K. (Department: 3745)
Power plants
Pressure fluid source and motor
Having a mechanical clutch or brake device in the power train
C092S020000, C188S26400E
Reexamination Certificate
active
06543222
ABSTRACT:
The present invention relates to a braking system for braking a rotor relative to a stator, said system comprising brake disks disposed in a disk enclosure, which disks are distributed in a first series of disks secured to the stator and in a second series of disks constrained to rotate with the rotor relative to the stator, the system further comprising a brake piston device that can be caused to go between a braking configuration in which an active portion of said piston device co-operates with the brake disks so as to urge said disks into braking contact, and a brake release configuration, the system further comprising control means for controlling the piston device, which control means comprise braking resilient return means continuously urging the brake piston device towards its braking configuration, a brake release chamber distinct from the disk enclosure and suitable for being fed with pressurized fluid via a brake release duct so as to urge the brake piston device into its brake release configuration, and a braking chamber suitable for being fed with pressurized fluid so as to urge the brake piston device towards its braking configuration, the braking system further comprising a cooling device for cooling the brake disks by means of fluid flow.
Such a braking system is a multi-effect braking system. It makes it possible to provide parking and emergency braking by means of the presence of the braking resilient return means which make braking possible when the brake release chamber is not fed with pressurized fluid to an extent sufficient to increase in volume by overcoming the braking resilient return force. It also makes it possible to provide in-service or dynamic braking which serves to decelerate and to brake a vehicle driven by a motor including the braking system, under the effect of fluid being fed to the braking chamber. Thus, the brake disks are suitable for absorbing the energy produced on decelerating and stopping the vehicle.
It is known, e.g. from patents US 3 927 737 and US 3 946 837, that it is necessary to irrigate the brake disks of such a multi-effect brake with a cooling fluid. The cooling is achieved by a flow of fluid fed via a specific cooling duct that opens out in the disk enclosure. The flow of cooling fluid is removed to the outside of the casing of the braking system via another duct connected to a fluid return.
Thus, the casing of the braking system must be provided with two orifices for the cooling fluid circuit, an orifice for the brake release duct that feeds the brake release chamber, and an orifice for the braking duct that feeds the braking chamber. Four holes, each of which is connected to a specific fluid duct, are necessary since each of them needs special treatment. This increases production costs and complicates management of the braking system.
A braking system of the above-mentioned type is also known from EP-A-0 913 304, in which a tapping duct continuously connects the brake release chamber to the disk enclosure. The tapping duct is formed in a valve device which serves to facilitate emptying the brake release chamber when emergency in-service braking is necessary. The fluid tapped continuously from the brake release chamber serves to lubricate and to cool the brake disk assembly.
The tapping duct is disposed inside the braking system, between the brake release chamber and the assembly of disks. It can be accessed only by disassembling the brake. Maintenance operations are therefore difficult, lengthy, and costly.
An object of the present invention is to propose a braking system that is simplified compared with the above-mentioned prior art systems, and that overcomes the above-indicated drawbacks.
This object is achieved by the facts that, for the purpose of being fed with cooling fluid, the cooling device is provided with a cooling duct branching from the brake release duct and communicating with the disk enclosure, that the cooling duct is formed in a casing portion of the braking system, and that it is provided with means for limiting the quantity of cooling fluid tapped by the cooling duct from the brake release duct.
The cooling duct branches from the brake release duct, so the casing of the braking system is provided with a single orifice for feeding both the cooling circuit and the brake release chamber (an orifice further being provided for feeding the braking fluid with fluid). However, the cooling duct is connected to the brake release circuit upstream from the brake release chamber.
Cooling fluid flow depends on brake release fluid feed. In other words, cooling ceases when brake release is no longer effective, which is functional since the source of heating also ceases when the rotor stops rotating. In contrast, during the deceleration phase, the brake release chamber continues to be fed, so that the brake disks continue to be irrigated with cooling fluid.
In addition, the continuous flow of fluid in the brake release circuit makes it possible to maintain the temperature of the fluid at a value such that its viscosity is sufficiently low, e.g. lower than 40 cSt, to ensure that the interruption in brake release by emptying the brake release chamber takes place with a short response time, of about 0.2 seconds, even if the ambient temperature is low, e.g. lower than 0° C.
Compared with the braking system of EP-A-0 913 304, the braking system of the invention makes it possible to provide maintenance that is greatly simplified since, in order to access the cooling duct, it is not necessary to disassemble the brake, nor even the brake release duct assembly. The cooling duct is formed in a casing portion and it is not necessary to disassemble parts internal to the braking system in order to have access to it.
Advantageously, the cooling duct is connected to the brake release duct via a connection segment which is formed in a casing portion and which has an end that is situated at the outer periphery of said casing portion and that is closed by removable closure means.
In which case, to access the cooling duct, it is necessary merely to remove the closure means.
In addition, the quantity of cooling fluid tapped from the brake release duct is limited by the means provided for this purpose, so that tapping cooling fluid does not adversely affect brake release.
Advantageously, the cooling duct is connected to the brake release duct via a device for limiting the flow rate of the fluid through said cooling duct.
This device for limiting the flow rate constitutes simple means for limiting the quantity of cooling fluid tapped from the brake release duct.
The flow-limiting device is preferably situated in said connection segment. Thus, maintenance operations (cleaning, replacement, repair) on the flow-limiting device can be performed after merely removing the above-mentioned closure means. The flow-limiting device can even be implemented in the form of interchangeable cartridges disposed in the connection segment (which is preferably rectilinear). Various cartridges may be used to satisfy various conditions of use for the brake.
Advantageously, the flow-limiting device is provided, at least in part, in the closure means which are disposed so as to be interposed between the brake release duct and the outlet of the cooling duct in the braking system.
Thus, on the basis of “standard” manufacture, it is possible merely to change the closure means in order to adapt the flow-limiting device to suit the conditions under which the brake is to be used.
The flow-limiting device is advantageously constituted by a restriction via which the cooling duct is connected to the brake release duct.
Advantageously, the cooling duct is connected to the brake release duct via a calibrated valve that allows the fluid to flow from the brake release duct to said cooling duct only when the fluid pressure in the brake release chamber is at least equal to a determined pressure.
The calibrated valve makes it possible to prevent the tapping of the cooling fluid from causing the pressure to drop in the circuit for feeding the brake release chamber with fluid.
Case Jean-Claude
Rouillard Jean-Marie
Souply Jean-Pierre
Vidal Stephane
Ladas & Parry
Leslie Michael
Look Edward K.
Poclain Hydraulics Industrie
LandOfFree
Braking system for braking a rotor relative to a stator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Braking system for braking a rotor relative to a stator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Braking system for braking a rotor relative to a stator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3060421