TURBINE BRAKE DEVICE

Abstract: A turbine brake device including a bypass line (6) connec­ ting an inlet line (2) and an exhaust line (3) of an en­ gine (1) so as to guide air from the inlet line (2) to the exhaust line (3), a power turbine (7) rotatably dis­ posed in said bypass line (6) with its output shaft (26) being connected to a crankshaft (9) of the engine (1), and opening-closing means (11, 12) for opening said bypass line (6) upon engine braking.

Description: This invention is related to a turbine brake device according to the preamble of claim 1. As an apparatus which produces a braking force by an impeller, there is a proposal entitled "Braking device for vehicle equipped with an internal combustion engine" (Japanese Utility Model Koho No. 26244/1985). In the above application an oil pump includes a drive shaft and a drive gear which is engaged with a crank gear, and a gallery cut valve is disposed in the outlet conduit of the oil pump so as to close the oil passage. The gallery cut valve is actuated synchronizedly with an exhaust brake pressure bearing means, namely an exhaust brake valve (not shown). According to this idea, upon exhaust braking, in addition to a braking force by the exhaust valve there is generated another braking force by the impeller of the oil pump since the outlet conduit is closed by the gallery valve so that the impeller performs a negative work, which serves as a resistance against the crank gear of the engine via the gear. In this operation, however, there are some drawbacks. Namely, during the exhaust braking, since the impeller of the oil pump produces a resistance force against the crank gear, the temperature of the oil in the oil pan becomes so high. This means that an oil cooler should be provided. And, this construction basically requires oil, which is not favorable as a retarder. Besides, although there is provided the bypass line, while the gallery valve is being closed, the oil supply by the oil pump might be insufficient. A turbine brake device according to the preamble of claim 1 is known from CH-A-364 136. This turbine brake device comprises a bypass line connecting an inlet line and an exhaust line of an engine so as to let intake-air flow from the inlet line to the exhaust line; a power turbine rotatably disposed in said bypass line with its shaft being connected to a crankshaft of the engine; opening and closing means for opening said bypass line upon engine braking, one of which being disposed upstream and the other downstream of the power turbine; an exhaust brake valve being disposed in the exhaust line downstream of said bypass line; and opening-closing control means for opening said opening and closing means synchronously with said exhaust brake valve's throttling of said exhaust line so as to generate a braking force. It is an object of the invention to form a turbine brake device according to the preamble of claim 1, the controlling of which is amended. This object is achieved by the above turbine device comprising the characterizing features of claim 1. Further embodiments of the invention are disclosed in the sub-claims. The invention will be further described with reference to the accompanying drawings. Figure 1 is a systematic view showing a preferred embodiment of the present invention. Figure 2 is a schematic view showing an example of the prior art. Referring to Figure 2, the embodiment of a prior art invention is described. An oil pump d includes a drive shaft c and a drive gear b which is engaged with a crank gear a, and a gallery cut valve f is disposed in the outlet conduit e of the oil pump d so as to close the oil passage e. The gallery cut valve f is actuated synchronously with an exhaust brake pressure bearing means, namely an exhaust brake valve (not shown). "g" designates a bypass conduit, "h" an impeller of the oil pump d, and "i" an oil pan. According to this idea, upon exhaust braking, in addition to a braking force by the exhaust valve there is generated another braking force by the impeller h of the oil pump d since the outlet conduit e is closed by the gallery valve f so that the impeller h performs a negative work, which serves as a resistance against the crank gear a of the engine via the gear b. Now a preferred embodiment of this invention will be described in accordance with the accompanying drawings. In Figure 1, 1 indicates an engine, 2 an intake-air passage connected to the intake manifold 28 of the engine 1, and 3 an exhaust passage connected to the exhaust manifold 29 of the engine 1. In the upstream of the intake-air passage 2, an air-cleaner 4 is provided so as to eliminate sand and dust from the air taken in and supply the cleansed air into the engine 1. In the exhaust passage 3 a silencer 5 is provided so as to suppress the noise downstream thereof. And, there is provided a bypass line 6 which is branched from the intake-air passage 2 downstream of the air cleaner 4 and combined to the exhaust passage 3 just upstream of the silencer 5. In the bypass line 6, there is disposed a power turbine 7 which is rotated by the air flowing in the bypass line 6. This power turbine 7 includes an impeller 27 and a shaft 26 which is used as an input shaft for driving the power turbine which works as a compressor. At the end of the shaft 26 an output gear 8 is fixed. The shaft 26 has clutch means 25 such as an electromagnetic clutch that disconnects the power turbine 7 and the crankshaft 9. In the bypass line 6 upstream of the power turbine 7, there is provided a shut-off valve 11 for opening/closing the bypass line 6, and there is provided a throttling valve 12 for adjusting the magnitude of the section of the bypass line 6. Also, in this embodiment, there is provided in the bypass line 6 upstream of the shut-off valve 11 a resonator 13 for reducing the noise upon introducing the air. The shut-off valve 11 and the throttling valve 12 are respectively actuated by actuators 16a and 16b, which are driven by the air from an air tank 17, via levers 14a and 14b, both of which levers being fixed to the shut-off valve 11 and the throttling valve 12, respectively. 17a and 17b are action chambers of the actuators 16a and 16b, respectively, and both of which chambers are connected to the air tank 17 via air conduits 18a and 18b. These air conduits 18a and 18b are switched by electromagnetic valves 19a and 19b, which have ports (not shown) opening to the external atmosphere, respectively. 20 indicates return springs of the actuators 16a and 16b. 21 indicates an exhaust brake valve, which is well known in the art, disposed in the exhaust passage 3 upstream of the junction of the bypass line 6 and the exhaust passage 3. The exhaust brake valve 21 is provided in a manner such that when it is actuated, i.e., when it is fully closed, the exhaust pressure is raised, which bears a braking effort against the engine.. The exhaust brake valve 21 is driven via a lever 14c also by the air supplied through the air conduit 18c, which has an electromagnetic valve 19c, from the air tank 17. The electromagnetic valves 19a, 19b, and 19c are all electrically connected to opening-closing control means 24, in a manner such that the electromagnetic valves 19a and 19b are turned ON upon exhaust braking. During normal driving, namely driving without exhaust braking, since the electromagnetic valve 19a is OFF, the shut-off valve 11 closes the bypass line 6, and the air cleansed by the air cleaner 4 is introduced through the intake-air passage 2 into the engine 1 and discharged to atmosphere through the exhaust passage 3 via the silencer 5. At this time, the clutch means 25 of the shaft 26 does not connect the power turbine 7 and the crankshaft 9, and hence the power turbine 7 does not perform any work against the engine. During the exhaust braking, on the other hand, the electromagnetic valves 19a and 19b are turned ON, actuating the actuators 16a and 16b, so that the shut-off valve 11 opens the bypass line 6, and at the same time the throttling valve 12 is moved to an optimum position. Said clutch means 25, this time, connects the power turbine 7 and the crankshaft 9 via the gear train 10. Therefore, when the power turbine 7 discharges the air induced through the bypass line 6, the power turbine 7 substantially works as a compressor of low efficiency, imposing a large negative work on the crankshaft 9. Hence, a desired braking effort is aquired. The air compressed by the power turbine 7 has passed through the air cleaner 4 so that obstacles which might brake the power turbine 7 have been eliminated. And, since the resonator 13 and the silencer 5 are disposed in the bypass line 6 and the exhaust line 3 respectively as noise eliminators, noise is not produced upon turbine-braking. Meanwhile, the shut-off valve 11 may be located at the entrance of the housing of the power turbine 7 and the throttling valve 12 at the exit thereof. And, the throttling valve 12 can be replaced by a movable nozzle vane which changes the sectional magnitude of the throat of the power turbine 7.

Claims: A turbine brake device comprising: a bypass line (6) connecting an inlet line (2) and an exhaust line (3) of an engine (1) so as to let intake-air flow from the inlet line (2) to the exhaust line (3); a power turbine (7) rotatably disposed in said bypass line (6) with its shaft (26) being connected to a crankshaft (9) of the engine (1); opening and closing means (11, 12) for opening said bypass line (6) upon engine braking; and control means (24) for opening said opening and closing means (11, 12) synchronously with an exhaust brake valve's (21) throttling of said exhaust line (3) so as to generate a braking force; characterized by an exhaust brake valve (21) being disposed in the exhaust line (3) upstream of said bypass line (6); and in that said opening and closing means (11, 12) consists of a shut-off valve (11) disposed upstream of the power turbine (7) and a throttle valve (12), which can adjust the magnitude of the section of the bypass line (6), disposed downstream of the power turbine (7). A turbine brake device according to claim 1, wherein the shaft (26) of said power turbine (7) is connected to the crankshaft (9) of the engine (1) via a gear train (10). A turbine brake device according to claim 1 or 2, wherein the shaft (26) of said power turbine (7) is connected to said crankshaft (9) via a clutch means (25).

Inventors: SEKIYAMA, SHIGEO KAWASAKI FACTORY OF
Applicants: ISUZU MOTORS LIMITED
Application year: 1988
Main classification: F02D9
IPC codes: F02D29, F02D9, F02D23, F02B67