DE102006002327A1 - Mass balance for use in V-8 crankshaft, has eight balancing weights, which engage within base bearing, where each balancing weight produces approximately equally large balancing force - Google Patents

Abstract

The balance has four crank throws that are arranged in the cross form. Each of the crank throws with adjacent crank throws forms an angle of exclusively 90 degrees, in the crank shaft for reduction of residual mass force from the oscillating mass forces. The residual mass force is not equalized by a balancing weight and acts in a center of a base bearing. Eight balancing weights (31-38) engage within the base bearing, where each of the balancing weights produces approximately equally large balancing force.

Description

The Invention relates to mass balance in the bases of a V8 crankshaft, especially in the crankshaft for one V8 / 90 ° -formula 1 engine.

formula 1 engines are over with speeds Operated at 18,000 rpm. The square with the speed increasing and not completely require compensating by balancing weights oscillatory mass forces at this speed level not only large friction-relevant basic bearings, but lead also to strong vibrations, the durability of the engine unit compromise.

The both, off-center to the crankshaft center engaging connecting rods produce in different piston positions different sizes on the basic bearing acting mass forces 1st order, whereby by the balancing weights only an averaged balancing of the 1st order mass forces possible is. The mass forces 2.Ordnung are oppositely directed alternating forces with double crankshaft frequency, occur like the mass forces 1st order also in the cylinder axis and are in the upper Kolbentotpunkten additive to the forces 1st order effective.

With Balancing weights, nominally the generated rotary inertia forces and 1st order mass forces 100% balance, remain due to the off - center working planes of the oscillating mass forces in the crank throw nevertheless in the basic camps effective oscillating mass forces 1. and 2nd order, which at maximum speed of the engine in height the ignition pressure load exceed several times.

in the Difference to the V8 motor vehicle engine in the crankshaft of the V8 racing engine, the base camp not on the proportionately acting ignition pressure, but be dimensioned to the oscillating residual mass forces, the practically effective as a permanent load in the base camp and not like the ignition pressure only for a short while two crankshaft revolutions acting on the basic bearing.

The larger required Lead diameter of the basic bearings to correspondingly high friction losses and reduce the delivered power of the racing engine.

The The invention therefore has the task of a crankshaft for the V8 racing engine with a mass balance, in which the residual mass forces in the Base stocks reduced to about the value of the acting Zünddruck share to reduce friction with smaller diameters of the basic bearings lower and increase the engine power and the engine vibrations to be able to reduce.

The solution of the object according to the invention is to be shown on the embodiment of a V8 / 90 ° -formal 1 motor with the following selected dimensions:
With a cylinder spacing (a) of 90 mm results in a piston diameter of 84 mm and a stroke of 54 mm, a displacement of the engine of 2394 cc.

The supporting bearing width of a basic bearing is assumed to be 17 mm. A crankpin or connecting rod bearing should have a bearing bearing width of 22 mm. This connecting rod width is therefore with about (0.25 a) chosen so high because in contrast to the basic bearing a Hubzapfenlager without compensation possibility by the oscillating mass forces of a cylinder plus the rotating mass share of a connecting rod is loaded.

With Outlet radii of the common crank pin to the two Hubzapfenwangen of 2 mm each and outlet radii of the basic bearing of 2 mm remains in the crank throw for two Hubzapfen cheeks each have a thickness of 10.5 mm, the possible thickness for balance weights to disposal stands.

Of the allows common crankpin in the crank throw a larger connecting rod width, because with a Hubzapfenversatz two Auslaufradien between the two staggered Hubzapfen provided at the expense of the two connecting rod widths Need to become.

The Pushrod ratio is set at (0,2), which is a connecting rod length of 135 mm and the radius of the balance weights in the crankshaft may be about 87 mm. In the load of the base camp through the oscillating mass forces become the mass forces 2nd order taken into account, because they are 20% of the mass forces 1st order make out.

Within the crank throw are the center distances the cylinder to the two basic bearings (0,622a / 0,378 a) and the center distances the balance weights (0.825a / 0.175 a).

Of the Cylinder bank offset of the two cylinder rows is 22 mm and corresponds to a connecting rod width.

( 1 ) shows the lever ratios in the crank throw for the embodiment.

In the familiar V8 / 90 ° crankshaft, the central third base bearing ( 23 ) by the two attacking, each other at an angle of 180 ° standing crankshafts ( 12 . 13 ) is highest loaded by the acting oscillating mass forces.

( 2 ) points to the base camp ( 23 ) resulting bearing load from the oscillating mass forces 1st and 2nd order, which can not be reduced by balance weights, since in the crankshafts ( 12 . 13 ) arranged balancing weights would also form an angle of 180 ° to each other and they in their balancing effect in the base camp ( 23 ) cancel each other, as well as for the rotating mass forces of the cylinder ( 2 . 6 and 3 . 7 ) the case is.

At a speed of 18000 rpm, the load with (0.487 P ₁ ) reaches a height which is approximately 2.5 times the value of the basic bearing ( 23 ) acting ignition pressure from the cylinders ( 3 or 6 ), where (P ₁ ) means the oscillating mass force of the 1st order of a cylinder.

The basic bearing dimensioned for this load ( 23 ) is for manufacturing reasons on the lower burdened by the oscillating inertial forces base camp ( 21 . 22 . 24 . 25 ) with serious disadvantages in terms of loss friction and engine performance.

The known V8 / 90 ° crankshaft with its mass balance by six balancing weights a concept for Motor vehicles, wherein the oscillating mass forces at Speeds of about 6000 rev / min compared to the Zünddruckkräften a minor role play.

For one V8 racing engine is this solution therefore too disadvantageous.

( 3 ) shows in the crank star of the exemplary crankshaft ( 41 ) for a V8 / 90 ° -Rennmotor a mass balance concept for a reduced residual mass force in the central base camp ( 23 ) by specially arranged crankshafts ( 11 to 14 ) and with eight balance weights ( 31 to 38 ) according to claim 1,

( 4 ) to ( 3 ) associated longitudinal view.

With the arrangement of the cranks ( 11 to 14 ), the same prerequisites for the basic camps ( 22 to 24 ) created.

The V8 / 90 ° crankshaft (41) produces a constant revolving rotating mass momentum of approximately (5.657 P ₁ .a), a constant circumferential 1st order mass moment of about (2.828 P ₁ · a), and a mass moment 2 effective in the transverse direction of the engine. Order of about (0-2,828 P ₂ · a), where (Pr) means the rotating mass force and (P ₂ ) the oscillating mass force 2nd order of each cylinder and (a) stands for the cylinder spacing.

With the balance weights ( 31 to 38 ) the basic camps ( 21 to 25 ) relieved of the inertial forces as well as the rotating moment and the 1st order moment fully balanced.

The 2nd order moment is a change moment with double crankshaft frequency.

Standard five-cylinder standard crankshafts produce, for example, a 1st-order moment of about (0.225 P ₁ · a) and a 2nd-order moment of (4.98 P ₂ · a).

In In-line five-cylinder test engines with balance shafts, both moments could in their impact compared with each other. It showed that the generated Tumble of the engine by the numerically smaller by about a factor of 22 Moment 1st order is subjectively perceptible, in contrast, the numerically 22-fold higher moment 2nd order only by measurement on the test bench can be detected.

It is explained this with the fact that the 2nd order alternating torque 2nd order with double frequency the motor in opposite Tries to tilt directions while maintaining the inertia of the Engine mass one too big Resists opposition.

Compared with the _second- order moment of (4.98 P ₂ · a) in the in-line five-cylinder engine, the crankshaft ( 41 ) second order of (2,828 P ₂ · a) of the cylinder number by 60% heavier V8 comparatively result in the five-cylinder effects, which are compared to the (4.98 P ₂ · a) of the series engine by about 65% lower and therefore sink in the V8 engine mass.

Produced in the crankshaft ( 41 ) according to claim 2 of each balance weight ( 32 to 37 ) a balancing force of the size (1.0 Pr + 0.48 P ₁ ) and each balancing weight ( 31 . 38 ) a balancing force of about (1.0 Pr + 0.50 P ₁ ), so that all rotating mass forces are fully balanced.

In the relation of the design example of (P ₂ = 0.2 P ₁ ), a residual force remains from the oscillating mass forces of the 1st and 2nd order in the base camps ( 22 to 24 ) of approximately (0.213 P ₁ ) and in the two bases ( 21 . 25 ) of at most about (0.26 P ₁ ), as in ( 5 ) and ( 6 ).

This is in the crankshaft ( 41 ) compared to the mass balance in the known V8 crankshaft in the central base camp ( 23 ) remaining Residual mass decreased by 56%. For the slightly larger balance weights ( 31 . 38 ) reaches a thickness of 10.5 mm.

According to claim 3 are used to maximize the connecting rod widths in the crankshaft ( 42 ) eight smaller balance weights ( 31 to 38 ) between the crankshafts ( 11 to 14 ) and in addition two balancing weights ( 51 . 52 ), as in ( 7 ).

( 8th ) shows in a flattened representation of the associated longitudinal view of the crankshaft ( 42 ) and

( 9 ) the changed lever ratios in the crankshafts ( 11 to 14 ).

Were in the crankshaft ( 41 ) with the cranks ( 11 to 14 diametrically opposed counterweights ( 31 to 38 ) the mass forces generated in each crank throw ( 11 to 14 ) are balanced for themselves, are in ( 7 ) the balancing weights ( 32 to 37 ) are arranged in such a way that in the plane of action of the resultant of the acting rotating forces and 1st order forces, the base camp ( 22 to 24 ) relieve.

The balancing weights required to compensate for this become smaller, because the compensation of a resultant requires less compensation forces as the respective balance of individual forces.

Produced in the crankshaft ( 42 ) each balance weight ( 31 to 38 ) a balancing force of approximately (0.849 Pr + 0.406 P ₁ ) and each balancing mass ( 51 . 52 ) in the associated basic warehouse ( 21 . 25 ) has a balancing force of approximately (0.565 Pr + 0.301 P ₁ ), the residual mass force remaining from the 1st and 2nd order forces in the bases ( 22 to 25 ) each (0,228 P ₁ ) and in the bases ( 21 . 25 ) converted each (0.274 P ₁ ).

The of the balancing weights ( 51 . 52 ) in their arrangement plane to be generated equalizing forces are the smaller, the larger the lever arms (b, c) to the crankshaft center ( 40 ) to get voted.

For the balance weights ( 31 to 38 ) of the crankshaft ( 42 ) is sufficient for a radius of 87 mm, a thickness of 9 mm, with which conrod widths of 23.5 mm can be used.

Since the outer base camp ( 21 . 25 ) have a higher residual mass force than the inner basic bearing ( 22 to 24 ), according to claim 10 the basic storage ( 21 . 25 ) of the higher load correspondingly widened.

In the embodiment of the crankshaft ( 42 ), a widening from 17 mm to 20.5 mm is proposed for the same diameter.

In the crankshafts ( 41 . 42 ), from the crank throw ( 11 ) off in the direction of crank throw ( 14 ) and read in a clockwise direction, are the crankshafts ( 11 to 14 ) in this order ( 11 - 12 - 13 - 14 ) arranged.

It should be noted that with an opposing bend arrangement ( 11 - 14 - 13 - 12 ) slight changes for the balancing weights ( 31 to 38 ) and for the balancing weights ( 51 . 52 ).

Each balance weight ( 31 to 38 ) then generates a required balancing force of (0.849 Pr + 0.44 P ₁ ) and the balancing weights (51, 52) in the associated base bearings ( 21 . 25 ) a balancing force of (0.565 Pr + 0.267 P ₁ ). The Restmas senkenkt in the bases ( 22 to 24 ) is then converted at about (0.234 P ₁ ) and in the base camps ( 21 . 25 ) each about (0,264 P ₁ ).

The claims 4 to 7 describe advantageous arrangements and embodiments of the balancing masses ( 51 . 52 ).

In claim 8 is proposed, the crankshafts ( 41 to 43 ) without balancing weights ( 31 to 38 ) in highly heat-treatable material and the balance weights ( 31 to 38 ) according to claim 9, for example by laser beam welding with the crankshafts ( 41 to 43 ) connect to.

It is understood that a crankshaft ( 43 ) with deviating from the two embodiments geometric values in the crankcases ( 11 to 14 ), for differently positioned balance weights ( 31 to 38 ), for differently chosen degrees of balance of mass forces in the base camps ( 21 to 25 ), for V8 engines with a V-angle deviating from 90 ° and possibly with staggered crank pins ( 1 to 8th ) in the crankshafts ( 11 to 14 ), according to claim 11 analogous to the exemplary crankshafts ( 41 . 42 ) without departing from the scope of the present invention.

For the V8 racing engine with a crankshaft ( 41 to 43 ) Finally, a lightweight and space-saving four-valve exhaust system is proposed, in which four Auspuffkrümmern the exhaust intervals are 270 ° and 450 °, including for a row of cylinders, the exhaust ports of the first and second and the third and fourth cylinder and for the other cylinder row of the first and fourth as well as the times and third outlet channel each lead into an exhaust manifold.

1 till 8

the Cylinders assigned Hubzapfen

11 until 14

cranks

21 to 25

main bearing

31 to 38

counterweights

40

crankshaft center

41 to 43

V8 Crankshaft

51 52

Leveling compounds

61

flywheel

a

cylinder spacing

b c

Distances to crankshaft center

pr

rotating Mass force of a cylinder

P ₁

oscillating Mass force 1st order of a cylinder

P ₂

oscillating 2nd order mass force of a cylinder

Claims (11)

Mass balancing in V8 crankshafts with four crankshafts arranged in a cruciform manner, in particular for V8 racing engines, characterized in that in the crankshaft (in 41 to 43 ) for the reduction in the central base camp ( 23 ) in the sum effective and not by balancing weights ( 31 to 38 ) balanced residual mass force from the oscillating mass forces 1st and 2nd order each crank throw ( 11 to 13 ) with its next following crank throw ( 12 to 14 ) forms an angle of only 90 °, within the basic bearing ( 21 to 25 ) only eight balance weights ( 31 to 38 ) at the base camps ( 21 to 25 ) and each balance weight ( 31 to 38 ) produces an approximately equal balancing force. Mass balance according to claim 1, characterized in that in the crank star of the crankshaft ( 41 ), the balance weights ( 32 to 37 ) with their associated crankshafts ( 11 to 14 ) an angle of 180 ° and the balance weights ( 31 . 38 ) with the associated crankshafts ( 11 . 14 ) form an angle of about 179.5 °. Mass balance according to claim 1, characterized in that in the crank star of the crankshaft ( 42 ), to maximize the connecting rod width at the base camp ( 22 ) counterbalancing weights ( 32 . 33 ) with both crankshafts ( 13 . 14 ) an angle of 45 ° and with the base ( 24 ) counterbalancing weights ( 36 . 37 ) form an angle of 180 °, which at the central base camp ( 23 ) counterbalancing weights ( 35 . 36 ) with both crankshafts ( 11 . 14 ) an angle of 45 ° and with each at an outer base ( 21 . 25 ) counterbalancing weights ( 31 . 38 ) form an angle of 180 ° and in addition to the complete compensation of the rotating mass moment and the 1st order mass moment outside the basic bearing ( 21 . 25 ) each at one end of the crankshaft ( 42 ) on the crankshaft ( 42 ) acting balancing masses ( 51 . 52 ) are arranged. Mass balance according to claim 3, characterized in that the balancing mass ( 51 . 52 ) near the base camp ( 21 . 25 ) forms a balance weight. Mass balance according to claim 4, characterized in that one of the balancing mass ( 51 . 52 ) formed balance weight has a larger radius than the balance weights ( 31 to 38 ). Mass balance according to claim 3, characterized in that the balancing mass ( 52 ) in the flywheel ( 61 ) is arranged. Mass balance according to claim 6, characterized in that the balancing mass ( 52 ) by diametrically opposite material recesses in the flywheel ( 61 ) is created. Mass balance according to claim 1, characterized in that the crankshafts ( 41 to 43 ) without balancing weights ( 31 to 38 ) made of high-quality material and the balance weights produced separately from inferior material ( 31 to 38 ) with the crankshafts ( 41 to 43 ) are rigidly connected. Mass balance according to claim 8, characterized in that the balance weights ( 31 to 38 ) by electron or laser beam with the crankshafts ( 41 to 43 ) are welded. Mass balance according to claim 1, characterized in that the two outer basic bearings ( 21 . 25 ) of crankshafts ( 41 to 43 ) in relation to the internal bases ( 22 to 24 ) have a larger bearing width, which is adapted to the higher load by the residual mass forces accordingly. Mass balance according to claim 1, characterized in that a crankshaft ( 43 ) of the embodiments of the crankshafts ( 41 . 42 ) deviating geometric values in the crankshafts ( 11 to 14 ), for differently chosen degrees of balance of mass forces in the base camps ( 21 to 25 ), for changed positioning of the balancing weights ( 31 to 38 ) or for a V-angle deviating from 90 ° with possibly offset crank pins ( 1 to 8th ) in the crankshafts ( 11 to 14 ), analogous to the crankshafts ( 41 . 42 ) is designed.