Broad torque band producing intake manifold for an internal combustion engine

Claim 2

In an intake manifold for combustion air for a reciprocating internal combustion engine of the type where combustion air velocity through the manifold is a direct function of engine speed, an improvement comprising: (a) a first set of runners of equal length and cross-sectional area, the length of each first set runner corresponding to a harmonic frequency of the fundamental frequency of air at standard temperature and the cross-sectional area of each first set runner being such that at a first engine speed combustion air velocity through the runner is substantially equal to the velocity at engine maximum torque; and (b) a second set of runners of equal length and cross-sectional area, the length of each second set runner corresponding to a harmonic frequency of the fundamental frequency of air at standard temperature different from that for the first runner set and the cross-sectional area of each second set runner being such that at a second engine speed, substantially different from the first engine speed, combustion air velocity through the runner is substantially equal to the velocity at engine maximum torque.

Claim 3

The intake manifold claimed in claim 1 wherein the manifold includes at least one plenum centrally disposed along a longitudinal axis of the manifold, the longitudinal axis paralleling the longitudinal axis of the engine with which the manifold is used.

Claim 4

The intake manifold claimed in claim 2 wherein each runner of each of the sets curves from the plenum to an exit disposed to register with an individual one of the inlet ports of the engine with which the manifold is to be used.

Claim 5

The intake manifold claimed in claim 3 wherein the cross-sectional area of each set of runners is different.

Claim 6

The intake manifold claimed in claim 4 wherein the length of each set of runners is different.

Claim 7

The intake manifold claimed in claim 3 wherein the cross-sectional area of each of the first set of runners is larger than the cross-sectional area of each of the second set of runners and the length of each of the first set of runners is shorter than the length of each of the second set of runners.

Claim 8

The intake manifold claimed in claim 6 wherein each runner leaves the plenum substantially parallel to the longitudinal axis of the manifold and then turns laterally to its exit.

Claim 9

The intake manifold claimed in claim 1 wherein the manifold includes at least two plenums, each serving one of the runner sets, the runners of the first and second runner sets serving alternate of the engine's cylinders in the sense of the engine's firing order.

Claim 10

The intake manifold claimed in claim 8 wherein the runners of the first set of runners has entrances leaving their plenum elevationally higher than the entrances of the second set of runners leaving their plenum.

Claim 11

The intake manifold claimed in claim 9 wherein the cross-sectional area of each of the first set of runners is larger than the cross-sectional area of each of the second set of runners and the length of each of the first set of runners is shorter than the length of each of the second set of runners.

Claim 12

The intake manifold claimed in claim 10 wherein the manifold is adapted for a V-type engine with half of the runners of each set adapted to serve one of the engine's cylinder banks and the other half of the runners of each set adapted to serve the other of the engine's cylinder banks.

Claim 13

The intake manifold claimed in claim 11 wherein each runner leaves the plenum substantially parallel to the longitudinal axis of the manifold and then turns laterally to its exit.

Claim 14

The intake manifold claimed in claim 11 wherein the plenums are side-by-side on opposite sides of the longitudinal center lines of the manifold.

Claim 15

The intake manifold claimed in claim 13 wherein the runners of elevationally higher entrance from their plenums are longer and have a smaller cross-sectional area than do the runners of the other set.

Claim 16

The intake manifold claimed in claim 14 wherein the runners of the lower entrance from their plenum extend upwardly from their entrances from the plenum to their exits.

Claim 17

The intake manifold claimed in claim 15 wherein each of the runners of both sets of runners curves substantially 90° between its plenum and its exit.

Claim 18

An improved intake manifold for an internal combustion engine comprising: (a) means defining a plenum for receiving a fuel and air mixture from a carburetor; (b) means defining a first set of runners from the plenum, each runner of the first set having a length corresponding to a harmonic frequency of the fundamental frequency of air at atmospheric temperature which produces resonance at a first engine speed, and a cross-sectional area that produces a velocity of air in the runners at the first engine speed corresponding to the velocity of air at engine speed maximum torque; and (c) means defining a second set of runners from the plenum, each runner of the second set having a length different from the length of the runners of the first set and corresponding to a different harmonic frequency of the fundamental frequency of air at atmospheric temperature than the first set and which produces resonance at a second engine speed substantially different from the first, and a cross-sectional area that produces a velocity of air in the second runners at the second engine speed corresponding to the velocity of air at engine speed maximum torque; whereby, the two runner sets each produces relatively high engine torque at the engine speeds at which they produce resonance.

Claim 19

An improved intake manifold for an internal combustion engine comprising: (a) means defining a plenum for receiving a fuel and air mixture from a carburetor; (b) means defining a first set of runners from the plenum, each runner of the first set having a length corresponding to a harmonic frequency of the fundamental frequency of air at atmospheric temperature which produces resonance at a first engine speed, and a cross-sectional area that produces a velocity of air in the runners at the first engine speed corresponding to the velocity of air at engine speed maximum torque; and (c) means defining a second set of runners from the plenum, each runner of the second set having a length different from the length of the runners of the first set and corresponding to a different harmonic frequency of the fundamental frequency of air at atmospheric temperature than the first set and which produces resonance at a second engine speed substantially different from the first, and a cross-sectional area that produces a velocity of air in the second runners at the second engine speed corresponding to the velocity of air at engine speed maximum torque; whereby, the two runner sets each produces relatively high engine torque at the engine speeds at which they produce resonance.

Claim 20

The improvement claimed in claim 17 wherein: the plenum is central with respect to a longitudinal length of the manifold, which length parallels the length of the engine when the manifold is used.

Claim 21

The improvement claimed in claim 18 wherein: each runner of each of the sets curves from the plenum to an exit disposed to register with an individual one of the inlet ports of the engine with which the manifold is to be used; each runner of each of the sets along its curve has a trapezoidal cross-sectional shape with the wall on the inside of the curve being a short side of the trapezoid and the wall on the outside of the curve being a long side of the trapezoid, the trapezoid shape being such as to produce substantially equal static pressure throughout the cross section; and the cross-sectional area of each runner of each set being substantially equal to the cross-sectional area of each other runner of its set and being constant throughout its length, the cross-sectional area of each runner in the first set being different from that of each runner of the second set.

Claim 22

The improvement claimed in claim 19 wherein the manifold is adapted for an in-line engine and the exit of each of the runners is at a plane common to all the exits of the runners.

Claim 23

The improvement claimed in claim 20 wherein each of the runners of both sets of runners has a cross-sectional shape change from trapezoidal to circular near the exits of the runners.

Claim 24

The improvement claimed in claim 20 wherein: the runners of the first set are shorter than the runners of the second set and the cross-sectional area of each runner of the first set is larger than the cross-sectional area of each runner of the second set.

Claim 25

The improvement claimed in claim 18 wherein the manifold is adapted for an in-line engine and the exit of each of the runners is at a plane common to all the exits of the runners.

Claim 26

The improvement claimed in claim 23 wherein: the runners of the first set are shorter than the runners of the second set and the cross-sectional area of each runner of the first set is larger than the cross-sectional area of each runner of the second set.

Claim 27

The improvement claimed in claim 24 wherein each runner extends from the plenum substantially parallel to the longitudinal axis and then turns laterally to its exit.

Claim 28

The improvement claimed in claim 25 wherein the runners have a common central plane.