JPS5920852B2 - Engine braking device and braking method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION SUMMARY DISCLOSURE An engine braking system and method is disclosed that provides improved engine braking and improved engine performance following braking action.

The present invention relates to a turbocharged internal combustion engine with variable compression engine braking, the turbocharger consisting of a turbine with dual inlets.

In addition, a diverter valve is provided which is controlled by an electrical control system and is suitable for diverting the entire flow of exhaust gas to one part of the turbine.

The combination of the present invention increases the deceleration horsepower produced by the engine by increasing the flow rate of air through the engine and increasing the temperature and pressure of the exhaust manifold.

The improved braking performance results from the faster turbocharger speed and the increased engine temperature that occurs in the engine during braking.

FIELD OF THE INVENTION This invention relates generally to engine braking systems and braking methods.

More specifically, the present invention is a compression-adjustable engine brake equipped with a turbocharger, the turbocharger including a turbine and a compressor, the turbine having a divided volute chamber and a shunt-adjustment valve controlled by an electrical control system. The combination provides improved engine braking and improved engine performance, as will be seen from the detailed description below.

The turbocharger of a turbocharged engine is usually not required during braking.

The reason is that no fuel is supplied to the engine.

For this reason, the volume and temperature of the exhaust gas decreases.

This has two adverse effects.

(1) The engine operating temperature drops below the desired temperature because the cooling system removes more heat than it generates.

(2) Reduction in the generated exhaust gas volume (causing a reduction in the speed of the ζ turbocharger due to the reduction in gas volume due to the lack of combustion and the temperature drop of the gas).

These adverse effects occur when operating on long downhill slopes,
For example, this is what is experienced when engine braking is required.

By the time you reach the bottom of the downhill slope, the engine temperature has decreased considerably and the turbocharger speed has also decreased.

Under these conditions, it is usually difficult to accelerate the engine immediately following a downhill slope (even if required to operate on a steep uphill slope).

These adverse effects are generally overcome by providing a braking system that combines a turbocharger consisting of an exhaust gas turbine with compressive engine braking.

Here, the turbocharger is an adjunct to the braking system, and the braking action is accompanied by an improved action of the turbocharger.

The brake system of the present invention maximizes the air flow into the engine during braking by controlling the turbocharger and diverting all exhaust gases through one section of the turbine, thereby reducing the compression effort by the engine. increase

DISCLOSURE OF THE INVENTION More particularly, the present invention provides an engine braking system with improved engine performance for an internal heat engine having an intake manifold and an exhaust manifold. An exhaust gas comprising a compression adjustment engine brake that operates when an engine cylinder connected to the exhaust valve is opened near the end of a compression stroke, and an air compressor that supplies a divided vortex chamber and compressed air to an intake manifold of the engine. a turbine in combination with a turbocharger, said turbocharger including a diverter regulator operatively connected at one side thereof to said exhaust manifold and at its other end to said divided volute. and directing, under the predetermined braking action, an exhaust gas flow originating from the exhaust manifold under the predetermined braking action to only one portion of the split volute rather than to both portions under the control of an electrical control system. To provide an engine braking device characterized by:

DESCRIPTION OF THE INVENTION By diverting the exhaust gas flow through a portion of the turbine, the gas pressure off the exhaust manifold is increased.

This effect not only increases the deceleration horsepower produced by the engine, but also increases the temperature of the air in the engine.

The increased air temperature then increases the energy of the exhaust gas, which further increases the efficiency and thus the rotational speed of the turbine.

Thus, the synergistic effect of increasing the deceleration horsepower produced by the ζ compression braking in combination with the ζ compression braking and the turbocharger having a segmented volute chamber.

Another advantage of this combination for normal operation of the invention results from its braking action.

During braking, a portion of the vehicle's kinetic energy is converted to heat, which is dissipated through the engine cooling system, thereby maintaining the engine at or near its normal operating temperature.

In prior art devices, the compression brake (see US Pat. No. 3,220,392) functions only as a normal brake.

Also, in prior art devices, a turbocharger (U.S. Pat. No. 4,008
No. 572, No. 3559397, No. 3137477,
No. 3,313,518 or No. 3,975,911) typically function to increase the air flow rate and thereby increase engine power during fueling.

To the best of our knowledge, the operation of turbocharged engines has been improved by the use of compression adjustment brakes, and the operation of compression adjustment brakes has been improved using turbocharged engines with split volutes and split flow adjustment mechanisms. No one is aware of the potentially ameliorating synergistic effects available.

Further advantages of the novel combination according to the invention will become apparent from the following detailed description of the invention and the accompanying drawings.

Referring specifically to FIG. 1, the engine is designated by the reference numeral 10. As shown in FIG.

This engine 10 may be either a spark ignition type or a compression ignition type, and may have any number of cylinders.

However, the present invention will be described with respect to a typical six cylinder compression ignition engine equipped with an intake manifold 12 and a split exhaust manifold consisting of a front exhaust manifold 14 and a rear exhaust manifold 16.

Exhaust ducts 18 and 20 lead from the front and rear manifolds, respectively, to an exhaust gas flow control valve 22.

This exhaust gas flow control valve 22 is shown in FIGS. 4 and 5 and will be described in more detail below.

A segmented exhaust gas duct 24 communicates between the outlet of the flow control valve 22 and the segmented volute chamber of a two-part inlet or turbine 26, said turbine 26 having a compressor 28 and an integral turbocharger. form 30.

This turbocharger 30 is shown in FIG. 3 and will be described in more detail below.

After passing through the turbine 26, the exhaust gases enter the engine's exhaust system 32.

Normal engine air purifier 34, compressor inlet duct 36
, via compressor 28 and inlet manifold duct 38;
Air is introduced into engine 10.

Note that the inlet manifold duct 38 is connected to the air compressor 2.
8 and the intake manifold 12 are communicated with each other.

As shown schematically in FIG. 1 and in more detail in FIG. 3, compressor 28 is driven by turbine 26 and typically includes an integral turbocharger 30.

Referring now to FIG. 2, engine 10 is fitted with a housing 40 which includes a conventional compression variable braking system shown schematically in FIG.

Oil 42 from an oil sump 44, such as the crankcase of an engine, is pumped up through a duct 46 by a low pressure pump 48 to an inlet 50 of a solenoid valve 52 mounted on the housing 40.

Low pressure oil 42 is routed from a solenoid valve 52 to a control cylinder 54 which is also mounted in the housing 40 through a duct 56.
will be guided through.

A control valve 58 is reciprocally mounted within the control cylinder and is urged into a closed position by a compression spring 60.

This control valve 58 connects an inlet duct 62 which is closed by a spherical check valve 64 biased to a closed position by a compression spring 66.
and an outlet duct 68.

When the control valve is in the open position (as shown in Figure 2),
The outlet duct 68 mates with a control cylinder outlet duct 70 which communicates with the inlet of a slave cylinder 72 also formed in the housing 40.

It will be appreciated that low pressure oil 42 passing through solenoid valve 52 flows into control valve cylinder 54 and forces control valve 58 to an open position.

Ball check valve 64 then opens against the bias of spring 66, allowing oil to flow into slave cylinder 72.

The oil 42 flows from the outlet lower 4 of the subordinate cylinder 72 to the duct 76
and into a master cylinder 78 formed in the housing 40.

A slave piston 80 is reciprocatably mounted within slave cylinder 72.

The slave piston 80 is biased upwardly toward the adjustable stop 82 (see FIG. 2) by a compression spring 84 that is mounted within the slave piston 80 and seated in the slave cylinder 72. Bracket 8
It is working towards 6.

The lower end of slave piston 80 acts toward an exhaust valve cap 88 mounted on the stem of an exhaust valve 90 seated in engine 10 .

Exhaust valve spring 92 normally biases exhaust valve 90 into a closed position as shown in FIG.

Typically, an adjustable stop 82 provides a desired clearance between the dependent piston 8
0 and the exhaust valve cap 88, so that when the exhaust valve is closed the subordinate piston seats against the adjustable stop 82 and the engine is cooled to obtain the desired clearance. When the engine is hot, the exhaust valve 90 is not opened, but the exhaust valve 90 is adapted to the expansion of the parts constituting the exhaust valve system, and the opening timing of the exhaust valve is controlled.

A master piston 94 is reciprocally mounted within the master cylinder 78 and biased upwardly by a light leaf spring 96 (see FIG. 2).

The lower end of the master piston 94 is controlled by a push rod 102 driven from the engine camshaft (not shown).
is in contact with.

When solenoid valve 52 opens, oil 42 lifts control valve 58 and then slave cylinder 72 and master cylinder 1.
It is understood that both conditions 8 and 8 are satisfied.

Backflow of oil from slave cylinder 72 and master cylinder 78 is prevented by the action of ball check valve 640.

However, once the system is filled with oil, upward movement of push rod 102 drives master piston 94 upward, and hydraulic pressure then drives slave piston 80 downward to open exhaust valve 90.

The valve timing is adjusted so that the exhaust valve 90 opens near the end of the compression stroke of the cylinder with which it is associated.

Thus, the work accomplished by the engine piston in compressing air during the compression stroke is released to the engine's exhaust system and is not recovered during the engine's expansion stroke.

In some engines it is advantageous to actuate the master piston from an injector push rod linked to the cylinder with which the slave piston communicates, while in other engines it is advantageous to actuate the master piston from an injector push rod linked to the intake or exhaust valve for another cylinder. It is preferable to use a stick.

In either case, the exhaust valve opens near the end of the compression stroke, so the result is the same.

If you want to reduce the power of the compression adjustment brake, use solenoid valve 5.
Block 2.

As a result, the oil 42 in the control valve cylinder 54 flows into the oil sump 44 via the duct 56, the solenoid valve 52, and the return duct 104.

As the control valve 58 moves downward, a portion of the oil in the slave cylinder 72 and master cylinder 78 is discharged from the control valve 58 and returned to the oil sump 44 by duct means (not shown), as shown in FIG. do.

The electrical control system for the present invention is schematically illustrated in FIG. 2A, to which reference will now be made.

Vehicle badge! J-106 has one terminal grounded 108
do.

The other battery terminal is connected in series to a fuse 110, a dash switch 112, a clutch switch 114, a fuel pump switch 116, and preferably to return ground 108 via a diode 118.

In addition, the multi-position selection switch 120 is replaced by the switches 112 and 1.
14 and 116 in series.

To vary the degree of braking force through the engine reducer and exhaust diversion system, it is desirable to use a selection switch with three contact positions, as shown in FIG. 2A.

\At contact position 1 (see Figure 2A), press the selection switch),
The switch 120 energizes the front engine brake solenoid 122.

This solenoid 122 controls, for example, solenoid valves 52 (three in the case of the six-cylinder engine shown in FIG. 1) that are connected to half of the engine cylinders.

In contact position 2, the selection switch 120 selects between the front engine solenoid 122 and the rear engine solenoid 12.
4 to control solenoid valves 52 in communication with all cylinders of the engine to increase engine braking.

In contact position 3, selection switch 120 energizes all solenoid valves 52 as well as
The diverter valve 22 is also energized via 6 to obtain maximum engine braking power, as will be explained in more detail below.

It will be appreciated that further contacts may be added to the selection switch 120 so that engine braking can be applied to one or more engine cylinders as desired.

Of course, the selection switch 120 may be omitted if maximum engine braking, that is, braking by the shunt control valve 22 in addition to all engine cylinders, is always required.

Switches 112, 114 and 116 are provided to complete the control system and ensure safe operation of the control system.

The switch 112 operates the manual part ah and disables the entire system.

Switch 114 is an automatic switch that disables this system whenever the clutch is disengaged to prevent the engine from stalling.

Switch 116 is a second automatic switch connected to the combustion system to prevent engine fueling when engine braking is applied.

Referring now to FIG. 3, a typical turbocharger 30 that may be used with the present invention is shown.

This turbocharger 30 consists of a twin rotor turbine and a compressor 28 coaxially mounted on a shaft 128 rotatably supported by a bearing 130 provided in a stationary housing 132.

The turbine 26, designated herein as a radial flow turbine, has a segmented volute chamber 1 with twin nozzles 136, 138 directed at the blades of an impeller 140 fixed to the shaft 128.
Contains 34.

The gas flowing through the segmented volute 134 is directed to the nozzle 136.1.
38 , it is accelerated and imparts kinetic energy to the impeller 140 .

It will be appreciated that the speed of the impeller 140 is a function of the volume of gas flowing through the volute 134 which determines the speed of flow through the nozzles 136,138.

It is known that at relatively low gas flow rates, the efficiency of the turbine decreases, and that greater efficiency can be achieved at low gas flow rates by directing all the gas into a portion of the volute. .

Impeller 140 of turbine 26 is coupled to impeller 142 of compressor 28, shown herein as a centrifugal compressor.

Impeller 1420 rotation draws air through inlet port 144 and delivers pressurized air through compressor volute 146 to inlet manifold duct 38 .

Although a radial flow turbocharger is shown and described, various types of turbochargers may be used with the present invention.

The only proviso is that the turbine is of a type in which all of the exhaust gas used as the driving fluid is delivered to the turbine wheel section as desired.

4 and 5 show the exhaust gas flow from ducts 18 and 20 to a portion of duct 240 and from there to turbine 26.
2 shows a typical shape of a diverter valve 22 suitable for diverting only a portion of a volute 134.

As shown in the drawing, the flow control valve 22 consists of a pair of relatively thin plates 148 and 150, which are connected to the duct 1.
8, 20 and the split duct 24 to form a housing suitable for placement therebetween.

These plates are attached to the plates 148 and 150) 18,
Bolt holes 152 for fixing to the flanges provided at 20 and 20 are provided.

An opening 154 is formed in each plate 14B, 150.

With the butterfly valve 156 within the opening 154, the stub shaft 15
Installed on 8,160.

The stub shaft is rotatably supported relative to the plates 14B, 150 and rotates from a closed position substantially parallel to the plates to an open position substantially perpendicular to the plates. It is something.

With the second butterfly valve 162 within the opening 154, the shaft 164
Attach to.

The shaft is rotatably journalled relative to the plates 148, 150 such that from a closed position substantially perpendicular to the plates, the plane of the butterfly valve 162 is relative to the plane of the plates 148, 150. It rotates to the open position at an acute angle.

When the butterfly valve 156 is in the open position and the butterfly valve 162 is in the closed position, the flow of gas from the duct 18. It will be understood that it goes into

However, when butterfly valve 156 is in the closed position and butterfly valve 162 is in the open position, ducts 18 and 20
The gas flow from the turbine 260 is diverted into a portion of the split duct 24 and then into a portion of the split volute 134 of the turbine 260 .

The positions of the butterfly valves 156 and 162 only need to be adjusted for fully open and fully closed positions.

Accordingly, these butterfly valves can be readily energized by the solenoid 126 (FIG. 2A) through suitable linkages (not shown) as would be understood by those skilled in the art.

These biasing mechanisms do not form any part of the present invention and will not be described in detail herein.

Although the specific shape of the diversion valve has been illustrated and explained,
It will be appreciated that various types of split control valves or flow control mechanisms may be used with the present invention.

However, this device is capable of diverting all of the engine exhaust gases into a single duct directed only toward the turbine section, thereby increasing the efficiency and speed of the turbine even at low exhaust gas flow rates. The condition is that.

Figure 6 shows Jacobs Manufacturing Link
1 is a pressure-volume diagram of a Mack 676 compression ignition engine equipped with a compression engine brake manufactured by Kompany; FIG.

The portion of the diagram from point 1 to point 2 shows the compression stroke of the engine starting at bottom dead center (BDC).

Before the piston reaches top dead center (TDC), engine braking causes exhaust valve 90 to open and cylinder pressure begins to drop.

At point 2a, the compression stroke ends, the piston reverses its motion, and once the engine is fueled, the "power" stroke begins.

Point 3 marks the end of the "power" stroke at bottom dead center BDC.

The diagram from point 3 to point 4 shows the exhaust stroke, - point 4
The line from to point 1 represents the intake stroke.

During the compression and exhaust strokes, work is accomplished by the engine compressing air in the cylinders, while during the power and suction strokes the engine distributes stored energy to the engine cooling system and exhaust system. ing.

Therefore, the area in the diagram 4ζ is proportional to the deceleration horsepower generated by the engine using prior art Jacobs engine braking.

FIG. 8 (Curve A) is a graph showing the variation of deceleration horsepower versus engine speed for a Matsukuro 76 compression ignition engine equipped with a Jacobs engine brake of the type schematically illustrated in FIG.

In accordance with the present invention, Applicant provides a diverter valve of the type shown in FIGS. 4 and 5 for use in the exhaust manifold of a Makuro 76 engine equipped with a turbocharger and Jacobs engine brake.

Significant improvements in engine braking performance and engine operating performance are shown in FIGS. 7 and 8 with respect to braking performance.

FIG. 7 is a pressure-volume indication chart similar to FIG. 6, but it shows the effect of adding a branch acceleration valve.

A significantly higher maximum pressure is achieved in the compression stroke, while the curve in the "power" stroke remains relatively unchanged.

Therefore, the area between the curves proportional to deceleration horsepower has increased.

Similarly, the maximum pressure (as well as the intermediate effective pressure) during the exhaust stroke has increased, and the area between the exhaust and intake stroke curves and the deceleration horsepower indicated thereby has also increased.

Curve B in FIG. 8 is a graph of the deceleration horsepower generated by the device according to the invention.

At all engine speeds within the engine's useful operating range, the retarding horsepower produced by engine operation in accordance with the present invention is greater than the retarding horsepower that would be produced if the engine were operated with standard Jacobs spray only. It should be noted that.

Among other things, usually encountered during the use of engine braking,
At higher engine speeds, the improvement in braking performance is greatly enhanced.

The improved braking performance is believed to be due to the joint action of the Jacobs engine brake and the turbocharger having a split volute and a flow control valve.

When operating on a long hill, for example when engine braking is required, the engine is operating near the top of its operating speed range, but the engine is not receiving fuel.

As a result, the volume and temperature of the exhaust gas are reduced.

This produces the two adverse effects explained at the beginning.

These adverse effects are eliminated by diverting all of the resulting exhaust gas through a portion of the turbine, so that the velocity at the turbine nozzle increases with increasing compressor speed.

With the increased speed of the compressor, more air is supplied at the inlet of the engine, thus increasing the compression work by the engine as shown by curve 1'-2' in FIG. Increase compared to 2.

In particular, the effect of the diverter valve is limiting off the exhaust manifold, which results in increased resistance during the exhaust stroke.

This latter effect is illustrated by comparing curve 3'-4' of FIG. 7 with curve 3-4 of FIG.

This increased work done by the engine during the compression and exhaust strokes is reflected in the increased temperature of the exhaust gases.

Note that this temperature also increases the volume of exhaust gas.

As can be seen from the foregoing, increasing the exhaust gas volume increases the turbine speed, which in turn increases the amount of air supplied to the engine via the compressor.

Thus, the combination of a compression modulating engine brake and a turbocharger with a shunt valve provides the synergistic effect that the compression modulating brake functions in an improved manner and functions as an exhaust brake.

Furthermore, not only the braking performance is improved, but also the operating performance of the engine.

As previously mentioned herein, it is often possible for an uphill slope to be immediately followed by a long downhill slope where engine braking is required.

However, at the end of the descent, the engine's temperature has dropped considerably and the turbocharger has also slowed down.

Under these conditions, as mentioned earlier herein,
It is difficult to accelerate the engine all at once.

With the combination according to the invention, not only is the temperature of the engine increased (because the work is increased due to the increased air flow during engine braking), but also the speed of the turbocharger is increased. Maintained by the combined effect of the diverter valve and increased airflow.

Thus, the turbocharger will operate at the higher speed needed to rapidly accelerate the engine.

Yet another performance advantage is that higher temperatures and greater airflow at the start of the engine's fueling cycle result in more complete combustion and
and the avoidance of exhaust smoke emissions with attendant loss of power.

There are also benefits to maintaining engine temperature and high air flow to prevent carbon build-up during operation in engine braking mode.

The combination according to the invention includes the function of increasing the pressure in the exhaust manifold, somewhat similar to an exhaust brake in this regard.

This avoids one of the main drawbacks of exhaust brakes, namely floating of the valve body.

Typically, exhaust manifold pressure is limited by the requirement that the exhaust valve spring force must not be exceeded.

However, the use of the engine brake ensures the fact that the pressure on the combustion side of the exhaust valve is substantially greater during the intake cycle (ζ than the pressure that would occur if only the exhaust brake was used).

This increased pressure allows the compression brake to operate at higher manifold pressures without the problem of valve float.

By eliminating valve float, higher exhaust manifold pressure is maintained, thus providing additional retardation horsepower.

Another advantage resulting from the combination of the invention concerns the performance reliability of the turbocharger.

The effect of further sifting the suction manifold pressure is to reduce the differential pressure across the turbocharger from the compressor to the turbine.

This means reducing the side thrust on the turbocharger bearings and improving turbocharger reliability.

Yet another advantage of the present combination of engine and exhaust brakes designed to produce similar retarding horsepower is pressure reduction in the turbine housing, which increases the life of the turbine and its reliability. be.

Although the exhaust brake necessarily increases the pressure in the exhaust manifold.

The combination of the present invention, on the other hand, increases manifold inlet pressure with only a relatively expensive increase in exhaust manifold pressure.

The fact that the present invention produces the same reduction horsepower with only a slight increase in exhaust manifold pressure means that stresses in the turbine housing are lower and thus turbine life is improved.

The terms and expressions used herein are for descriptive purposes only and are not limiting.

Also, the use of such terms and expressions means that
Nothing is intended to exclude equivalents or portions of equivalents of the features shown and described (it is to be understood that various modifications may be made within the scope of the claimed invention).

[Brief explanation of the drawing]

FIG. 1 is a partially cut-away illustration of an engine with a compression control brake, an exhaust gas diverter and a turbocharger with two inlets, namely a split volute chamber turbine;
2A is a schematic diagram of the electrical control system of the improved engine speed reducer according to the present invention; FIG. 4 is a plan view of a butterfly-shaped shunt control valve used in the present invention; FIG. 5 is a sectional view taken along the line 5-5 in FIG. 4; FIG. 7 is a P-V indicator chart showing the pressure-volume relationship occurring in the engine cylinder during one complete stroke of a prior art operation using a compression brake; FIG. 7 is an engine cylinder according to the present invention. The P-■ indicator chart diagram and FIG. FIG. 3 is a graph diagram showing the deceleration horsepower. 10...Engine, 12...Intake manifold, 14.16...Exhaust manifold, 1B
, 20...Exhaust duct, 22...Diversion control valve, 24...Surface division duct, 26...Turbine, 28...Turn compressor, 30... ...Turbocharger, 32...Exhaust system, 34...
Air purifier, 36...Compressor inlet duct, 38
...Inlet manifold duct, 40...
Housing, 42... Low pressure oil, 44... Bent oil sump, 46... Item, 48... Low pressure pump, 50... Commercial Department, 52... ... Solenoid valve, 54 ... Control cylinder, 56 ...
・Duct, 58... Control valve, 60, 66° 84
... Compression spring, 62... Merchant Rodact, 64.
... Ball check valve, 68, 70 ... Outlet duct, 72 ... Dependent cylinder, 74 ...
・Outlet, 76...Duct, 78...Master cylinder, 80...Subordinate piston, 82
...Adjustable stopper, 86...Bracket, 88...Exhaust valve cap, 9o...Curved exhaust valve, 92...Exhaust valve spring, 94...・・・・・・
Master piston, 96...Plate spring, 98...
...Adjustment screw mechanism, 100...Rocker arm, 102...Press rod, 104...
Return duct, 106...Vehicle battery, 1
08...Earth, 110...Fuse,
112... Dash switch, 114...
...Clutch switch, 116...Fuel pump switch, 118...Diode, 120...
...Multi-position selection switch') f, 122, 124, 12
6...Engine brake renoid, 128,
164...shaft, 130...bearing, 13
2... Stationary housing, 134... Divided spiral chamber, 136, 138... Dual nozzle, 1
40,142... Impeller, 144...
Inlet port, 146...Bent compressor volute, 148 F15
0...Plate, 152...Pol) JL,
154... Opening, 156... Butterfly valve, 158, 160... Stub shaft, 162...
...Second butterfly valve.

Claims (1)

[Claims] 1. In a gas compression adjustment type engine braking device for an internal combustion engine equipped with a turbocharger, the turbocharger has a turbine connected to the exhaust manifold of the engine, a compressor driven by the turbine, and an intake manifold of the engine. The turbine includes a split exhaust duct 24 coupled at its upstream end to a gas diverter regulator 22 and subsequently coupled to the engine's split exhaust manifolds 14, 16 by exhaust ducts 18, 22. both a split volute which is supplied with exhaust gas by the turbine and a turbine which directs all the exhaust gas supplied into only one of the split exhaust ducts 24 and from there during normal engine operation. an electrically operated control system (FIG. 2A) which operates a diversion valve during braking to divert the flow into one of the volutes rather than into the volute; Brake device. 2. The apparatus of claim 1, wherein the turbine comprises a radial flow turbine. 3 The diversion valve is a butterfly valve energized by a solenoid 1
56. Apparatus according to claim 1 or 2, which is 56. 4. A braking method with improved engine performance for an internal combustion engine-driven vehicle equipped with an engine having a turbocharger and a compression-adjustable engine brake, in which the turbocharger is equipped with a divided volute chamber, and the compression-adjustable engine brake rotational speed assuming that when the engine is energized to a predetermined limit, exhaust gas is directed from the exhaust manifold of the engine to one part of the divided volute chamber, and the exhaust gas is directed to both parts of the divided volute chamber; increasing the rotational speed of the turbocharger, increasing the flow rate of air passing through the turbocharger as a function of the increased rotational speed of the turbocharger and suppressing the exhaust gas flow from the exhaust manifold, and subsequently increasing the air flow through the turbocharger; an improvement characterized in that it results in improved braking and engine performance when continuously compressing the flow of air and releasing the increased flow of compressed air into the exhaust manifold near the end of the compression stroke of the engine. Braking method with improved engine performance. 5. The method of claim 4, wherein the exhaust gas flow is directed through both portions of the split volute when the compression engine brake is de-energized.