CA1156841A - Turbocharger - Google Patents

Abstract

ABSTRACT

A turbocharger system for supplying charge air to a combustion engine includes a nonventilated hydraulic turbine mounted directly on the turbocharger shaft. The nonventilated hydraulic turbine is selectively driven by a high pressure hydraulic fluid to drive supplementally the turbocharger during engine operating conditions when additional air flow to the engine is required.

Description

This invention reIates to turbocharger systems for use with combustion engines. More specifically, the invention relates to a turbocharger system including hydraulic assist apparatus and methbd for supplementally driving the turbo-charger at predetermined engine operating conditions.

Turbochargers and turbocharger systems are well known in the art, and typically comprise a turbine wheel and a compressor wheel mounted on a common shaft. The turbine wheel and the compressor wheel are mounted within iso-lated turbine and compressor housings, which in turn aremounted on a so-called centre housing including shaft bearings and lubricant circulation passages. The turbine housing includes a gas inlet and a gas outlet, and is coupled to a combustion engine for passage of engine ex-haust gases for rotatably driving the turbine wheel. Therotating turbine wheel correspondingly drives the compres-sor wheel which compresses ambient air and supplies the compressed alr, commonly referred to as charge air, to the engine.

Turbocharged engines are highly advantageous when com-pared with conventional naturally aspirated engines in that substantially denser air is delivered to the combus-tion chamber or cylinders of the engine. This increased air density results in an increased mass flow of avail-able air for combustion to enable the engine to operate at substantially higher performance levels and with greater efficiency. However, an inherent limitation with turbochargers has been their inability to provide to the engine su~ficienk charge air during some conditions of engine operation. For example, charge air supplied to the engine by the turbocharger during low speed, full load conditions, or during low speed, acceleration conditions typically is insufficient to maintain desired engine performance levels. This inadequate flow of charge air i5 caused by a relatively low available energy level of engine e~haust gases to drive the turbocharger turbine wheel which in turn drives the turbocharger compressor wheel.

A variety of system concepts are known in the prior art for boosting or supplementing the normal charge air output of a turbocharge~ during certain engine operating conditions.
Some of tllese concepts relate to auxiliary combustion systems for controllably supplementing the energy level o~ the exhaust gases w~ith additional combustion energy to supplement dri~ing of the turbochar~er. See U. S.
Patent No. 3,988,894 for one example of this type of sys-tem. Other system concepts include multiple turbocharger turbine and/or compressor components coupled together, such as those shown by U. S. Patent Nos. 2,173,595,

2,898,731, 3rO05r306, 3,498,052, and 3,355~877. Turbo-charger arrangements with supplemental mechanical drive~
are shown by U. S. Pakent Nos. 2,386,096, 2,578,028, 2,585,029, and 2,585,968, whereas supplemental hyraulic dri~es are disclosed by U. S. Patent Nos. 3,389,554,

3,473,322, 3,921,403, 3,927,530 and 4,083,198. While all o~ these various system concepts provide at least -3- ~5~

some supplemental driving of a turbocharger, the relative expense and complexity of these systems has provided a significant obstacle to commercial application. Moreover, mechanically driven and hydraulic motor-driven systems include inherent maximum speed limitations which prevent their use with modern turbochargers including high speed components designed for rotational speeds on the order oE
about 100,000 R.P.M. or more.

Some prior art system concepts include hydraulic turbines for driving a centrifugal compressor to supply charge air to an engine. In some designs, the hydraulic turbine is embodied in a supercharger system, as in U. S. Patent No.
3,036,563. In other designs, the system proposes an hydraulic turbine for supplementally driving the turbo-charger as through a direct connection to the turbochargershaft. See U.S. Patent Nos. 2,968,914, and 3,869,866, and British Patent No. 4~8,396. However, these prior art hydraulic turbine systems have included so-called Pelton-type turbine wheels requiring a ventilated chamber for operation. Accordingly, any attempt to operate the Pelton turbine wheels at relatively high rotational speeds results in generation of large quantities of a foamy mix-ture of air and hydraulic fluid which must be dissipated before recirculation to the turbine wheel or to other sys-tem components. This is particularly disadvantageous whenthe hydraulic fluid is shared with another fluid system, such as an engine lubrication system, in that the foamy mixture does not return rapidly to liquid state, and can-not be used or pumped in foam form for use in the shared fluid system. Moreover, even when free-wheeling with khe turbocharger, Pelton-type turblne wheels are not capable of withstanding the high rotational speeds achieved by modern turbochargers. As a result, Pelton-type hydraulic turbine systems have not found commercial application in modern high speed turbocharyer environments.

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This invention overcomes the problems and disadvantages of the prior art by providing a turbocharger system specially adapted to include a nonventilated hydraulic turbine driven by an hydraulic fluid shared from another hydraulic system for controllably and supplemenkally driviny a turbocharger.

In accordance with the invention a turbocharyer for supplying charge air to a combustion engine, comprising an engine exhaust gas driven turbine including a turbine wheel carried within a turbine housing; a compressor for supplying engine charge air, including a compressor wheel carried within a compressor housing; a centre housing coupled between said turbine and compressor housings; a common shaft connected between said turbine and compressor wheels whereby said compressor wheel is rotatably driven by said turbine wheeI, bearing means carried within said centre housing for rotatably support ing said shaft; a nonventilated hydraulic turbine mounted on said shaft within a turbine flow chamber formed in said centre housing; and means for selectively supplying a fluid at a reJatively high pressure to said centre housing or rotatably driving sald nonventilated hydraulic turbine for supplementally driving said compressor wheel.

The accompanying drawings illustrate the invention. In ~5 such drawings:

Figure 1 is a schematic diagram illustrating the hydraulic assist turbocharger system of this invention;

Figure 2 is a fragmented vertlcal section of a turbochar-ger including a nonventilated hydraulic assist turbine;

Figure 3 is a per.specti~e view, partially exploded, of the hydraulic assist turbine and associated hydraulic nozzle;

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Figure 4 is a reduced fragmented vertical section taken on the line 4-4 of F.igure 2;

~igure 5 is an end view of the hydraulic nozzle taken on the line S-5 of Figure 3;

Figure 6 is a horiæontal section taken on the line 6-6 of Figure 3;

Figure 7 is an enlarged fragmented vertical section of the hydraulic nozzle of Figure 3;

Figure ~ is an enlarged fragmented perspective view of a portion of the hydraulic turbine; and Figure 9 is a schematic diagram illustrating an alternate arrangement of the invention.

An hydraulic assist turbocharger system 10 is shown in Figure 1, and generally comprises a turbocharger 12 for supplying relatively high density charge air to a combus-tion engine 14, such as a two-cycle or a four-cycle internal combustion engine. More specifically, the turbo-charger 12 includes a turbine wheel 16 and a compressor wheel 18 respectively received withi.n turbine and compres-sor housings 20 and 22. The turbine and compressorhousings 20 and 22 are interconnected by a centre housing 24 including bearings 26 such as suitable journal and thrust bearings for rotatably supporting a shaft 28 to which the turbine wheel 16 and the compressor wheel 18 are commonly connected.

The turbocharger turbine wheel 16 is rotatably driven by exhaust gases from the engine 14 which are supplied to the turbine wheel via an exhaust manifold 29 and an ex-haust conduit 30. If desi.red, the turbocharger turbine 30 housing 20 and the exhaust manifold 29 and conduit 30 may be adapted for divided, pulse-type operation such as -6~

that shown and described in U. S. Patent No. 3,292,364.
The rotating turbine wheel 16 rotatably drives the shaft 2~ and the compressor wheel 18, whereby the compressor wheel 18 draws in and compresses ambient air. This com-pressed ambient air comprises charge or boost air forthe engine 14, and is supplied to the intake manifold 32 of the engine via a charge air conduit 34. Conveniently, as shown, a charge air cooler heat exchanger 36 may be provided along the conduit 34 to cool the compressed charge air so as to reduce the to*al heat load of the engine and to further densify the charge air. The rela-tively high density charge air thus supplied to the en-gine 14 enables the engine to operate at a relatively high performance and efficiency level.

The engine 14 includes an hydraulic fluid system 38 which is coupled to provide shared hydraulic fluid to the turbo-charger for lubrication of the turbocharger bearings 26.
In a preferred embodiment o:E the invention, the engine hydraulic ~luid system 38 comprises an engine oil system, although other types of engine-driven hydraulic systems for other purposes are contemplated. As embodied in an engine oil system as shown in Figure 1, the hydraulic system 38 includes a reservoir 40 of hydraulic fluid or oil within the engine, and a relatively conventional ~ow pressure oil pump 42 for pumping oil from the reservoir 40 to the engine 14 and the turbocharger 12. More speci fically, the oil is pumped through an oil filter 44 and an oil cooler 46, and ~urther to engine components requiring lubrication as indicated by conduit 48. The oil is also coupled through a supply conduit 50 to the centre housing 24 of the turbocharger 12 for supply to the turbocharger bearings 26 via a network of internal passages (not shown in Figure 1) Eormed in the centre housing. The oil passes through the bearings 26, typi-cally as by agravity-drain system as will be hereafter described, and is returned to the engine oil reservoir ~7~ ~6~

40 as by a return conduit 54. Accordingly, the bearings 26 of the ~urbocharger 12 share the hydraulic system 38 with the engine 14 to assure that the turbocharger bearings 26 are properly lubricated at all times.

The turbocharger system 10 of this invention includes a nonventilated hydraulic turbine 56 for supplementally driving the turboch~rger compressor wheel 18 during c~r--tain modes of engine operation. That is, during some conditions of engine operation, the engine exhaust gases are incapable of rotatably driving the turbine wheel 16 at a speed sufficient to drive the compressor wheel 18 to supply the engine 14 with sufficient charge air. For example, such engine operating conditions may include relatively low speed, full load conditions wherein the available energy in the exh~ust gases is relatively low, or relatively low speed, acceleration conditions wherein there is insuf~icient excess charge air available to accommodate rapid transient operating conditions. To assure that the campressor wheel 18 is sufficiently driven to supply the engine with sufficient quantities of charge air, the turbocharger system includes the nonventilated hydraulic turbine 56 for selectively and controllably supplementally driving the compressor wheel 18.

AS illustrated in Figure 1, the nonven~ilated hydraulic turbine 56 is mounted within the centre housing 24 direct-ly upon the turbocharger shaft 28 between the sets of bearings 26 rotat~bly supporting the shaft. The nonven-tilated hydraulic turbine 56 is hydraulically driven by high pressure fluid or oil shared from the engine hydraulic system 38. That is, the hydraulic system 38 includes a high pressure pump 58 which may be suitably driven by the engine 14 to provi.de a source of high pressure fluid. As shown, the high pressure pump 58 has its intake coupled to the engine hydraulic system 38 con-veniently at the discharge side of the low pressure pump42. The high pressure pump 58 supplies high pressure oil -8~

to a high pressure supply conduit 60 coupled directly to a control va]ve 62 which comprises an hydraulic control valve. The control valve 62 is suitably operated to couple the high pressure oil ~low to the hydraulic tur-bine 56 via a line 64, or alternately to return tha out-put of the high pressure pump 58 to the engine hydraulic system 38 to substantially unload the pump 58. ~s shown, the output of the high pressure pump 58 is returned to the hydraulic system 38 by means of a bypass return con-duit 66 coupled to the bearing supply conduit 50. Con-veniently, a one-way relief valve 61 is connected bet~een the high pressure supply conduit 60 and the bearing supply conduit 50 to prevent excessive system oil pressures.

The control valve 62 is controlled in response to operat-ing parameters of the turbochargex system 10 -to control the operat:ion o~ the hydraulic turbine 56. As shown, one control scheme for the control valve 62 comprises connec-tion of the valve 62 with the output or discharge pres-sure of the turbocharger compressor wheeI 18 by means of a pressure control line 63. When compressor discharge pres-sure is at or above a predetermined minimum thre~hold, the control valve 62 responds to the pressure to return the output of the high pressure pump 58 to the hydraulic system 38 via the bypass return conduit 66. In this event, sufficient oil back pressu:re corresponding with the discharge pressure of the low pressure pump ~2 is available in the turbocharger bearing supply conduit 50 to maintain a relatively small oil flow, say on the order of about one gallon per minute, to the turbocharger bearings 26 for lubrication purposes. This bearing lub-rication oil circulates through the centre housing 24 in communication with the bearings 26 and then returns to the engine oil system 38 via the main return conduit 54.

When compressor discharge pressure falls below the pre-determined threshold value, the control valve 62 ~9 ~ 6~

automatically in response to the pressure shifts position to couple directly the output of the high pressure pump 58 to the nonventilated hydraulic turbine 56. That is, high pressure oil is fed into the high pressure supply line 64 which couples tha oil to the centre housing 24 for drlving supply to the nonventilated hydraulic turbine 56. The high pressure oil rapidly accelerates the non-ventilated hydraulic turbine 56 correspondingly to accelerate rapidly the turbocharger shaf-t 28. In this manner, the compressor wheel l~ is rapidly accelerated to increase substantially the pressure level of the compres-sor discharge charge air. This effectively provides the engine 1~ with additional or supplemental charge air to maintain the engine 14 in a high power load-carrying state in spite of the inability of the engine exhaust gases to drive adequately the turbocharger turbine wheel 16.

The high pressure oil is circulated through the nonventi-lated hydraulic turbine 56 at a relatively high ~low rate and pressure, say on the order of up to about twelve gallons per minute and up to about 1600 p.s.i. This high pressure oil is separated within the centre housing 24 from direct communication with air to prevent foaming.
The high pressure oil is also maintained separate from the bearing circulation pa-th to prevent flooding of the bearings 26, and to allow the high pressure oil to ~low into communication with the hydraulic turbine 56 at a relatively high flow rate. As illustrated in Figure 1, the oil drains from the nonventilated hydraulic turbine 56 through a one-way check valve 70 and a drain conduit 72 to the turbocharger bearing supply conduit 50. With this configuration, the oil flow returning to the engine hyaraulic system 38 via the conduit 50 is maintained at a sufficient back press~re to assure a reIatively small flow through the bearing oil supply network within the centre housing 24 to maintain bearing lubrication. Of -10- ~S~

course, the check valve 70 prevents bearing supply flow from communicating with the nonventilated hydraulic tur-bine 56 when the turbine 56 is not supplementally driven by high pressure oil.

~he construction of the turbocharger centre housing 24 and the mounting of the nonventilated hydraulic turbine 56 therein is shown in detail in Figures 2-8. As shown, the turbocharger centre housing 24 ls secured betwee.n the turbine and compressor wheels 16 and 18, respectively, which in turn are carried within the turbine and compres-sor housings 20 and 22 (not shown in Figure 2). The wheels 16 and 18 are fixed upon the shaft 28 which is ro-tatably carried within the centre housing 24 by means of a conventional thrust bearing assembly identified in Figure ~ by reference numeral 74, and a pair of generally opposed and conventional sleeve-type ~ournal bearings 126.
The journal bearings 126 are supplied with relatively low pressure lubricating oil by means of an oil inlet port 76 which is coupled to the bearing supply conduit 50 (not shown in Figure Z). The oil supplied to the port 76 is guided to the bearings via the internal supply passage network 52, and via holes 53 formed in the bearings 126.
From there, the oil drains gravitationally through openings 75 to the bearing oil return line 54 ~not shown in Figure 2) via a sump 78.

As shown in Figure 2, the nonventilated hydraulic turbine 56 is centrally carried on the shaft 28 within an enlarged flow chamber 80. More specifically, the nonventilated hydraulic turbine 56 is positioned in axially abutting relation with a shoulder 82 on the shaft 28, and is re-tained against axial excursions by a positioning sleeve 84 which is in turn retained in posi.tion by a thrust collar of the thrust bearing assembly 74. This sleeve 84 is contained concentrically within the left-hand journal bearing 126, which is in turn concentri~ally contained within a cylindrical high pressure nozzle 86. Convenient-ly, the nozzle 86 includes holes 88 registering with the bearing oil holes 53 so as to assure adequate lubrication of the left-hand journal bearing 126 as viewed in Figure 2, as well as a drain opening 77 registering with the adjacent bearing drain opening 75.

The nozzle 86 has a two-part construction in order to guide high pressure oil into driving communication with the nonventilated hydraulic turbine 56. That is, the nozzle 86 includes an inner portion 89 fixed in position by a set screw 87, and which cooperates at one end with an outer portion 90 fixed thereto as by brazing to define a generally semi-circular chamber 920 The chamber 92 communicates via a plurality of flow openings 91 with a high pressure oil inlet port g4 coupled to the high pressure supply conduit 64 (not shown in Figure 2) for receiving high pressure oil. The high pressure oil, when supplied to the chamber 92, flows through and out of the chamber 92 via a plurality of ~enerally semi-circularly arranged noz21e openings 96. Importantly, these nozzle openings 96 are oriented in a common angular direction with respect to the axis of the shaft 28 so as to impart a circumferentially turning motion to the nonventilated hydraulic turbine 56. That is, a,s best shown in Figure 25 7, the nozzle openings 96 are angled at about 75 or so with respect to the axis of the shaft 28 to direct the high pressure oil circumferentially against the turbine 56 to rotatably drive said turbine.

The nonventilated hydraulic turbine 56 comprises a central disc 98 received over the shaft 28, and a plurality of radially outwardly pro~ecting blades 100. These blades 100, as shown in Figures 3, 6, and 8, have a generally cup-shaped or U-shaped configuration presented openly toward the angularly directed oil jets passing from the 35 nozzle openings 96. The blades 100, are of course, arranged and aligned for direct impingement by the oil jets. Desirably, a circumferential shroud 102 is formed integrally about the radially outer ends of the blades 100 to improve driving coaction between the blades 100 and the oil jets.

In operation, high pressure oil supplied to the nozzle 86 is converted to high pressure oil jets for rapidly accele~
ratin~ -the nonventilated hydraulic turbine 56. The oil driving the turbine 56 substantially immediately floods the centre housing flow chamber 80 whereby the hydraulic turbine 56 operates in a nonventilated flooded environ-ment to prevent foami~g or frothing of the oil. The oil circulates out of the chamber 80 via an outlet port 104 coupled to the bearing oil supply line 50 (Figure 1).
Importantly, the reIative sizes of the inlet and outlet ports 94 and 104, together with the back pressure on the chamber 80 resulting from the presence of low pressure oil in conduit 50, a~sures substantially immediate flooding of the flow chamber 80 when oil is supplied thereto. Air in the flow c.hamber 80 is forced by the in-coming flooding oil outwardly from the chamber 80 in both directions along the shaft 28. That .is, the air is forced between the positioning sleeve 84 and the nozzle 86 for escape thro~lgh the drain openings 75 and 77, and in the other direction past a divider ring 106 secured in posi-tion by retaining rings 107for escape through the other drain opening 75. During supply of high pressure oil to the nonventilated hydraulic turbine 56, some oil may leak from the flow chamber 80 in both directions along the shaft 28. In this regard, the positioning sleeve 8~ in-cludes a slinger 73 aligned with the adjacent drain openings 75 and 77 for radially pumping any such leaking oil through said openings 75 and 77 to the sump 78.
Similarly, a slinger contour 71 is formed on the shaft 28 adjacent the divider ring 106 and opposite the flow cham-ber 80. This slinger contour 71 is aligned with the -13- ~ 4~

adjacent drain opening 75, and also functions to pump any leaking oil through the adjacent drain opening 75 to the sump 78. Importantly, both the slinger 73 and the slin-ger contour 71 are positioned inboard with respect to the journal bearings 126 so as to guard against flooding of said bearings.

When high pressure oil flo~ to the nonventilated hydraulic turbine 56 ceases, the remaining oil in the flow chamber 80 is rapi.dly pumped out of the ch~n~er to allow the tur~
bine 56 to freewheel with the turbocharger shaft 28 with-out significant resistance losses. More specifically, the oil remaining in the chamber 80 is pumped out of the chamber in both directions along the shaft 28 toward the journal bearings 126 by the spinning action of the shaft 28 and the nonventilated hydraulic turbine 56. Convenient-ly, the slinger 73 and the slinger contour 71 described above operate to prevent the pumped oil from contacting or flooding the turbocharger bearings 126. Accordingly, during all conditions of operation, the turbocharger journal ~earings 126 and the thrust bearing assembly 74 are lubricated solely by means of oil supplied via the passage network 52, with seal rings 108 being positioned at opposite ends of the shaft 28 to prevent any oil from l~aking into either the turbine housing 20 or the com-pressor housing 22.

An alternate embodiment of the invention is illustrated schematically in Figure 9, wherein components identical to those shown and described in Figures l-8 are desig-nated by common reference numerals. In this embodiment, a modified control valve 162 functions ~ptionally to couple the high pressure oil from the high pressure pump 58 through a conduit 109 to an hydraulic motor llO
coupled to drive a fan 112. The high pressure oil thus causes the fan 112 to force large quantities of cooling ambient air across cooling surface areas of a charye air cooler heat exchanger 136, before returning to the

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bearing supply line 50 via a return conduit 113. With this arrangement~ cooling capacity of the charge air heat exchanger136 is improved over that of the embodiment of Figure 1 to reduce further the temperature level of the charge air supplied to the engine 14. Conveniently, the need for improved charge air cooling normally arises when large quantities of charge air are supplied to the engine, namely, at relatively high boost levels of turbocharger operation. Therefore, the additional charge air cooling is required primarily when sufficient charge air is available, and is not required when supplemental dxiving of the turbocharger is needed. Thus, the control valve 162 operates to supply the high pressure oil to the tur-bocharger 12 under some engine opexating conditions for driving the nonventilated hydxaulic turbine 56, and to the hydraulic motor 110 for driving the charge air cooling fan 112 during other engine operating conditions.

~arious modifications and improvements to the invention set forth herein are believed to be possible within the scope of the art. For example, a variety of control schemes for the control valves ~2 and 162 are possible, including electronic systems and the like responsive to one or more engine and/or turbocharger operatin~ para-meters. Moreover, the invention is adaptable for use with conventional four-cycle internal combustion engines, or with two-cycle internal combustion engines. With two-cycle engines, the control scheme for the control valves 62 and 162 may be designed so as to supplementally drive the turbocharger in a manner allowing elimination of the conventional scavenging blower. Further, in the embodiment of Figure 9, the control valve 162 may be adapted also to couple the high pressure oil directl~
to the bearing supply conduit 50 via the line 66/ where-by the control valve 162 is capable of three-position operation to effect a) driving of the nonventilated hydraulic turbine 56 b) driving of the fan 112, or c) unloading of the high pressure oil pump 58. Still further, the nozzle 86 shown particularly in Figures 2-7 may be modified to include circumferentially arranged nozzle openings 96. These nozzle openings 96 may be divided in~o groups for association with two or more chambers 92 which may in turn be coupled to separately controlled, multiple high pressure fluid supply conduits.
Accordingly, no limitation of the invention is intended by way of the description herein except as set forth in the appended claimsv

Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A turbocharger for supplying charge air to a combus-tion engine, comprising an engine exhaust gas driven turbine including a turbine wheel carried within a turbine housing; a compressor for supplying engine charge air, including a compressor wheel carried within a compressor housing; a centre housing coupled between said turbine and compressor housings; a common shaft connected between said turbine and compressor wheels whereby said compressor wheel is rotatably driven by said turbine wheel; bearing means carried within said centre housing for rotatably supporting said shaft; a nonventilated hydraulic turbine mounted on said shaft within a turbine flow chamber formed in said centre housing; and means for selectively supplying a fluid at a relatively high pressure to said centre housing for rotatably driving said nonventilated hydraulic turbine for supplementally driving said compressor wheel.

2. A turbocharger as set forth in Claim 1, wherein said fluid supply means comprises a reservoir of fluid, a rela-tively high pressure pump for pumping fluid from said reservoir, conduit means for circulating said fluid through said flow chamber in said centre housing, and valve means for selectively opening and closing said conduit means to fluid flow.

3. A turbocharger as set forth in Claim 2, wherein the engine includes an hydraulic system including means for supplying lubricant fluid at relatively low pressure to said bearing means for lubrication thereof, said high pressure pump being for pumping fluid from said hydraulic system.

4. A turbocharger as set forth in Claim 3, wherein said centre housing includes an inlet port and an outlet port communicating with said flow chamber for passage of high pressure fluid therethrough, said outlet port being coupled to said means for supplying low pressure fluid to said bearing means so as to apply a back pressure to said flow chamber to cause substantially immediate flood-ing of said flow chamber when fluid is supplied thereto whereby said nonventilated hydraulic turbine operates in a substantially nonventilated environment.

5. A turbocharger as set forth in Claim 4, including pumping means for pumping air from said flow chamber when high pressure fluid is supplied thereto, and for pumping fluid from said flow chamber when fluid flow thereto ceases.

6. A turbocharger as set forth in Claim 5, wherein said bearing means comprises at least two bearings generally in opposition to each other with said flow chamber and nonventilated hydraulic turbine therebetween.

7. A turbocharger as set forth in Claim 6, wherein said pumping means on said shaft comprises first and second slinger means respectively on opposite sides of said flow chamber and inboard with respect to said bearings.

8. A turbocharger as set forth in Claim 1, including nozzle means mounted within said centre housing for receiving high pressure fluid, and for directing said fluid into driving communication with said nonventilated hydraulic turbine.

9. A turbocharger as set forth in Claim 8, wherein said nozzle means comprises a generally cylindrical member carried about said shaft, said cylindrical member includ-ing a nozzle chamber for receiving high pressure fluid, and a plurality of relatively small nozzle openings com-municating between said nozzle chamber and said nonven-tilated hydraulic turbine whereby the high pressure fluid is converted to a plurality of high pressure jets passing through said nozzle openings into driving commu-nication with said nonventilated hydraulic turbine.

10. A turbocharger as set forth in Claim 9, wherein said nozzle openings are uniformly formed angularly with res-pect to the axis of rotation of said shaft so as to im-part a circumferential turning motion to said nonventi-lated hydraulic turbine.

11. A turbocharger as set forth in claim 10, wherein said nonventilated hydraulic turbine comprises a central disc having a plurality of radially outwardly extending generally U-shaped blades, said blades being aligned radially with said nozzle openings and oriented openly toward the high pressure jets from said nozzle openings.

12. A turbocharger as set forth in Claim 11, wherein said nonventilated hydraulic turbine further includes a shroud circumferentially surrounding said blades.

13. A turbocharger for supplying charge air to a combus-tion engine, comprising an engine exhaust gas driven turbine including a turbine wheel carried within a turbine housing; a compressor for supplying engine charge air, including a compressor wheel carried within a compressor housing; a centre housing coupled between said turbine and compressor housings; a common shaft connected between said turbine and compressor wheels whereby said compressor wheel is rotatably driven by said turbine wheel; bearing means carried within said centre housing for rotatably supporting said shaft; a nonventilated hydraulic turbine mounted on said shift within a turbine flow chamber formed in said centre housing; an inlet port on said centre housing for receiving a relatively high pressure fluid, nozzle means communicating with said inlet port for directing high pressure fluid into rotatable driving communication with said nonventilated hydraulic turbine for supplementally driving said compres-sor wheel; an outlet port on said centre housing forming a discharge path for high pressure fluid from said flow chamber; means coupled to said outlet port for applying a fluid back pressure to said flow chamber to cause sub-stantially immediate flooding of said flow chamber when high pressure fluid is supplied thereto whereby said hydraulic turbine operates in a substantially nonventi-lated environment; valve means for selectively supplying high pressure fluid to said inlet port; and pumping means for pumping air from said flow chamber when high pressure fluid is supplied thereto, and for pumping fluid from said flow chamber when supply of fluid thereto ceases.

14. A turbocharger as set forth in Claim 13, wherein said bearing means comprises at least two bearings on said shaft generally in opposition to each other on oppo-site sides of said flow chamber, said pumping means on said shaft comprising first and second slinger means on opposite sides of said flow chamber and inboard with respect to said bearings.

15. A turbocharger for supplying charge air to a combus-tion engine including an hydraulic lubricant fluid system for supplying lubricant fluid at relatively low pressure to the engine and the turbocharger, comprising an engine exhaust gas driven turbine including a turbine wheel carried within a turbine housing; a compressor for supplying engine charge air, including a compressor wheel carried within a compressor housing; a centre housing coupled between said turbine and compressor hous-ings; a common shaft connected between said turbine and compressor wheels whereby said compressor wheel is rota-tably driven by said turbine wheel; bearing means carried within said centre housing for rotatably support-ing said shaft, said centre housing including lubricant supply passages for coupling said bearing means with the hydraulic system for lubrication of said bearing means;
a nonventilated hydraulic turbine mounted on said shaft within a turbine flow chamber formed in said centre housing; and means for selectively supplying a portion of the fluid from the supply system at a relatively high pressure to said centre housing for rotatably driving said nonventilated hydraulic turbine for supplementally driving said compressor wheel.