BRAKE SYSTEM

Abstract: The brake system comprises a shaft (16) interposed between two propeller shaft segments (a, a) via universal joints (17), a radial compressor (2, 15) selectively connected with the shaft (16), a casing (4) for housing the radial compressor (2) and the shaft (16) with the universal joints (17) being outside the casing (4), and stay members (47) mounted on the casing (4) for allowing the casing (4) to be hung from the vehicle body. The brake system has a radial compressor (2, 15) which is selectively connected with the propeller shaft (a, a) and consumes an energy of the engine. The energy consumed by the compressor (2, 15) serves as a brake force. The casing (4) is fixed to the vehicle body, so that the brake system also serves as a center bearing of the propeller shaft (a, a).

Description: The present invention relates to a brake system according to the generic part of the main claim. A brake system of this kind is described in FR-A-2 163 977. Generally, a large amount of heat exchange takes place in braking large vehicles such as a large bus or truck and usually such vehicles are equipped with an auxiliary brake system in addition to a main brake system (foot brake). In one type of the auxiliary brake system, such as an exhaust brake, the auxiliary brake system produces a force which comes from the vehicle wheel side toward an engine of the vehicle. The crankshaft of the engine is affected by such a force, thereby the engine is decelerated. In another type, a rotor is provided in a propeller shaft of the vehicle and it consumes an energy of the engine when it is rotated by the engine, whereby the rotor applies a brake force to the engine (DE-A-1 430 035). Figure 4 illustrates an example of an auxiliary brake system which is generally called "electrical retarder". The electrical retarder b has a casing, electromagnets and a rotor housed in the casing. An eddy current (Foucault current) is produced when the rotor rotates between the electromagnets, i. e., when the rotor rotates in the magnetic field. The electrical retarder b expells the eddy current (Foucault current) in the form of ohmic heat. It is advantageous to provide this brake system b between the propeller shafts a of the vehicle, since the electrical retarder b serves as a center bearing of the propeller shafts a . However, the rotor requires cooling since the electrical retarder generates considerable amount of heat. A cooling device raises the cost of the auxiliary brake system and makes the arrangement complicated. The problem of the present invention is to provide a brake mechanism which is compact and simple in construction, does not require a cooling device and functions as a brake system only. The invention solves this problem by the features described in the main claim. Advantageous further developments are described in the sub claims. According to one aspect of the present invention, there is provided a shaft ("input shaft" in the preferred embodiment) interposed between the propeller shaft segments as a part of the propeller shaft; a centrifugal compressor having a shaft ("drive shaft" in the preferred embodiment) parallel to the shaft (input shaft); a chain connecting the shaft (input shaft) with the shaft of the compressor and transmitting a power to the compressor from the engine via the propeller shaft; a clutch provided between the shaft (input shaft) and the compressor selectively transmitting the power from the engine to the compressor; a casing housing the shaft (input shaft) with either end thereof being outside the casing; and stay members mounted on the casing and allowing the casing to be hung from the vehicle body. The shaft (input shaft) is preferably coupled with the propeller shaft segments via universal joints respectively provided at the ends of the shaft (input shaft). In this arrangement, when the clutch connects the compressor with the propeller shaft, i. e., with the engine, the compressor consumes the energy of the engine, thereby applying a brake force to the engine. Since the shaft (input shaft) serves as a part of the propeller shaft, the casing looks like a center bearing of the propeller shaft. The casing is fixed to the vehicle by the stay members. Figure 1 is a sectional view of the brake device of the present invention; Figures 2 and 3 illustrate the brake device of Figure 1 when it is provided in a propeller shaft and mounted on a vehicle body via stay members respectively; and Figure 4 illustrates a conventional auxiliary brake system. A preferred embodiment of the present invention will be described with reference to the accompanying drawings. Referring to Figure 1, a power transmission line 3 of a brake system comprises two lines extending in a casing 4, namely a propeller shaft line 6 for branching an energy transmitted from the engine (not shown) and a centrifugal compressor drive line 5 for transmitting the branched energy to a centrifugal compressor 15. The centrifugal compressor drive line 5 extends above and parallel to the propeller shaft line 6. The compressor drive line 5 includes a clutch shaft 1, a coupling shaft 13, a multi-plate clutch 12, an intermediate shaft 14 and a compressor shaft 15, in a manner such that the clutch shaft 1 is coaxially connected with the coupling shaft 13 via the multi-plate clutch 12, and the coupling shaft 13 is connected with the compressor shaft 15 via the intermediate shaft 11. The propeller shaft line 6 includes an input shaft 16 extending parallel to the clutch shaft 1 in the casing 4 with either end protruding from the casing 4, a first sprocket 19 fixed to the clutch shaft 1, universal joints 17 (Figure 2) provided at each end of the input shaft 16 to be coupled with the propeller shaft a (Figure 2), a second sprocket 18 fixed to the input shaft 16, and a chain 20 engaged over the first and second sprockets 19 and 18. The shaft 16 is supported by bearings at position near the ends thereof. The vehicle has a divisible propeller shaft, like the illustration of Figure 4, and the brake mechanism is provided between the propeller shaft segments a as shown in Figure 2. Specifically, the input shaft is interposed between the propeller shaft segments a . Each universal joint 17 includes a joint member 52 which is coupled with another joint member 51 provided at one end of each propeller shaft segment a, and a bearing 50 (Figure 1) supporting the input shaft 16 in the casing 4. The rotation ratio between the clutch shaft 1 and the input shaft 16 can be adjusted by changing the sprocket 18 and/or the sprocket 19 even if the distance between the clutch shaft 1 and the input shaft 16 is fixed. An oil pan 44 is mounted on the bottom of the main casing 4. Referring back to Figure 1, the multi-plate clutch 12 includes a clutch wheel 21 transmitting power to the coupling shaft 13, first clutch plates 22 transmitting power to the clutch wheel 21 and second clutch plates 23 frictionally engaging with the first clutch plates 22 and transmitting power from the engine 12 to the first clutch plates 22. The first clutch plates 22 and the second clutch plates 23 are alternatively disposed in the axial direction of the clutch shaft 1. The clutch shaft 1 is coupled with the coupling shaft 13 when the multi-plate clutch 12 is in an engage mode, i. e., when the clutch plates 22 are pressed against the second clutch plates 23 by the pressure of the oil supplied from a passage 24 bored in the clutch shaft 1. The coupling shaft 13 is connected to the intermediate shaft 14 via gears, and the output gear of the intermediate shaft 14 meshes with a gear of the centrifugal compressor shaft 15. A compressor casing 32 which houses the compressor 2 is attached to the main casing 4 in such a manner that the axial direction of the compressor 2 corresponds to the axial direction of the clutch shaft 1. The compressor casing 32 is an involute casing and has an inlet 33 in the axial direction of the compressor 2 and an outlet 34 in the radial direction of the same. A throttle valve 41 is disposed in the inlet 33, and the degree of throttling is adjusted by control means 43. Referring to Figure 3, a pair of stay members 47 are mounted on the casing 4 on the upper lateral walls thereof via a pair of bushes 46 being elastic in the width direction thereof (width direction of the drawing). The stay members 47 are firmly mounted on a frame 48 of the vehicle by U-shaped members 49 at the other ends thereof. A clearance between the bottom of the oil pan 44 and the ground (not shown) is maintained due to the stay members 48 and the U-shaped members 49. The position of the casing 4 in the longitudinal direction of the vehicle is kept unchanged by these members, too. Therefore, the brake mechanism serves as a center bearing of the propeller shafts a . Referring back to Figure 1, when the clutch shaft 1 is coupled with the coupling shaft 13 by the clutch 12, the power from the engine (not shown) is branched from the input shaft 16 (or the propeller shaft) to the compressor shaft 15 via the endless chain 20, the clutch shaft 1, the coupling shaft 13 and the intermediate shaft 14, whereby the radial compressor 2 starts rotating. When the vehicle is running on a long downhill, for example, and the clutch 12 is in the engage mode, the compressor 2 inhales the air through the inlet 33, compresses the air in the impeller and expells the air through the outlet 34. In other words, the energy transmitted from the input shaft 16, i. e., the engine, is consumed by the compressor 2. The consumed energy serves as a brake force against the engine. The strength of the brake force is adjusted by the throttle valve 41.

Claims: A brake system adapted for a vehicle having an engine and a propeller shaft (a, a) having two segments, comprising a first shaft (16) having universal joints (17) at either end thereof and coupling it with the propeller shaft segments (a, a); and braking means (2, 15) connected with said first shaft (16), characterized by a radial compressor (2) having a second shaft (15) connected with the first shaft (16) and applying a brake force to the propeller shaft (a, a) when it consumes energy of the engine transmitted through the propeller shaft (a, a); a casing (4) housing the radial compressor (2) and the first shaft (16); and stay members (47) attached to the casing (4) and allowing the casing (4) to be hung from a body of the vehicle. A brake system as defined in claim 1, characterized in that a multi-plate clutch (12) is interposed between the second shaft (15) and the first shaft (16) in a manner such that it selectively connects the first shaft (16) with the second shaft (15). A brake system as defined in claim 1 or 2, characterized in that the second shaft (15) is connected with the first shaft (16) via a power transmission line which includes a multi-plate clutch (12). A brake system as defined in claim 3, characterized in that the power transmission line includes the multi-plate clutch (12), a clutch shaft (1) extending from the multi-plate clutch (12), a first sprocket (19) fixed on the clutch shaft (1), a second sprocket (18) fixed on the first shaft (16), an endless chain (20) connecting the first sprocket (19) with the second sprocket (18), a coupling shaft (13) extending from the multi-plate clutch (12) and an intermediate shaft (14) rotating with the coupling shaft (13) as well as the second shaft (15). A brake system as defined in anyone of the foregoing claims, characterized in that each of the stay members (47) has a mounting bush (46) at one end thereof and a U-shaped member (49) at the other end thereof in a manner such that each stay member (47) is attached to the lateral wall of the casing (4) via the mounting bush (46) and fixed to the vehicle body by the U-shaped member (49).

Inventors: OKADA, MASAKI C/O FUJISAWA FACTORY
Applicants: ISUZU MOTORS LIMITED
Application year: 1989
Main classification: B60T1
IPC codes: F02B67, F02D29, B60T1