Method and apparatus for measuring engine compression ratio, clearance volume and related cylinder parameters
First Claim
1. A method of measuring clearance volume VTDC wi the cylinder of an internal combustion engine having a piston disposed to reciprocate in said cylinder and a crankshaft coupled to said piston, said method comprising the steps of:
- (a) monitoring angular rotation of said crankshaft,(b) identifying an angular position θ
TDC of said crankshaft corresponding to top dead center of said piston within said cylinder,(c) measuring cylinder pressures Pa, Pb, Pc at angularly spaced positions θ
a, θ
b, θ
c of said crankshaft different from said top dead center position θ
TDC,(d) identifying volumes Va-b, Vb-c and Va-TDC of piston displacement between crankshaft positions θ
a, θ
b, θ
c and θ
a, θ
TDC respectively, and(e) determining at least clearance volume VTDC as a function of the following four equations involving the four unknowns Va, VTDC, γ and
k;
space="preserve" listing-type="equation">P.sub.a V.sub.a.sup.γ
=k
space="preserve" listing-type="equation">P.sub.b (V.sub.a +V.sub.a-b).sup.γ
=k
space="preserve" listing-type="equation">P.sub.c (V.sub.a +V.sub.a-b +V.sub.b-c).sup.γ
=k(f) determining said clearance volume as a function
space="preserve" listing-type="equation">V.sub.TDC =V.sub.a -V.sub.a-TDC.
1 Assignment
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Accused Products
Abstract
A method and apparatus for measuring compression ratio and/or clearance volume in an internal combustion engine cylinder wherein the crankshaft angle associated with piston top dead center position is obtained and cylinder pressure is measured at a number of incrementally spaced piston positions. Changes in cylinder volume between the incrementally spaced piston positions are determined from nominal engine design parameters. These multiple pressure and volume figures are then employed in a programmed microprocessor to determine the constants γ and k in the polytropic equation for relating cylinder pressure to volume PV.sup.γ =k. Clearance volume VTDC is determined using the constants γ and k, and measured pressure at TDC or incremental volume figures. Compression ratio is determined by the fraction (VDP +VTDC)/VTDC, where VDP is total piston displacement volume obtained from nominal engine design parameters. The invention is also implemented to determine cylinder leakage during the compression stroke, angles of operation of the intake and exhaust valves, effective compression ratio where the intake valve does not close at BDC, and/or cylinder intake pressure.
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Citations
26 Claims
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1. A method of measuring clearance volume VTDC wi the cylinder of an internal combustion engine having a piston disposed to reciprocate in said cylinder and a crankshaft coupled to said piston, said method comprising the steps of:
-
(a) monitoring angular rotation of said crankshaft, (b) identifying an angular position θ
TDC of said crankshaft corresponding to top dead center of said piston within said cylinder,(c) measuring cylinder pressures Pa, Pb, Pc at angularly spaced positions θ
a, θ
b, θ
c of said crankshaft different from said top dead center position θ
TDC,(d) identifying volumes Va-b, Vb-c and Va-TDC of piston displacement between crankshaft positions θ
a, θ
b, θ
c and θ
a, θ
TDC respectively, and(e) determining at least clearance volume VTDC as a function of the following four equations involving the four unknowns Va, VTDC, γ and
k;
space="preserve" listing-type="equation">P.sub.a V.sub.a.sup.γ
=k
space="preserve" listing-type="equation">P.sub.b (V.sub.a +V.sub.a-b).sup.γ
=k
space="preserve" listing-type="equation">P.sub.c (V.sub.a +V.sub.a-b +V.sub.b-c).sup.γ
=k(f) determining said clearance volume as a function
space="preserve" listing-type="equation">V.sub.TDC =V.sub.a -V.sub.a-TDC. - View Dependent Claims (2)
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3. A method of measuring angle of valve operation within the cylinder of an internal combustion engine having a piston disposed to reciprocate within said cylinder and a crankshaft rotatably coupled to said piston, cylinder pressure and volume being related to each other with all valves closed by the equation PV.sup.γ
- =k wherein P is pressure, V is volume and γ and
k are constants, said method comprising the steps of;(a) monitoring angular rotation of said crankshaft, (b) identifying an angular position θ
TDC of said crankshaft corresponding to top dead center of said piston within said cylinder,(c) measuring pressure within said cylinder at a multiplicity of angularly spaced positions of said crankshaft while said crankshaft is rotating and said piston is reciprocating within said cylinder, (d) identifying displacement volumes of said piston within said cylinder between at least some of said angularly spaced positions at which said valve is known to be closed, (e) determining said constants γ and
k as a function of said displacement volumes and said measured pressures,(f) comparing said measured pressures at the remainder of said angularly spaced positions to pressures P predicted by said equation, and (g) identifying angle θ
V of valve operation with respect to θ
TDC as a function of a difference between said predicted pressure and said measured pressure for each said angularly spaced position. - View Dependent Claims (4, 5, 6)
- =k wherein P is pressure, V is volume and γ and
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7. Apparatus for measuring clearance volume within the cylinder of an internal combustion engine having a piston disposed to reciprocate in said cylinder and a crankshaft coupled to said piston, said apparatus comprising
means for monitoring angular rotation of said crankshaft, means for measuring cylinder pressures at a multiplicity of angularly spaced positions of said crankshaft other than top dead center position of said piston within said cylinder, means for identifying volumes of piston displacement between said angularly spaced crankshaft positions, and means for determining clearance volume VTDC as a function of said displacement volumes and said cylinder pressures.
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9. Apparatus for measuring angle of valve operation within the cylinder of an internal combustion engine having a piston disposed to reciprocate within said cylinder and a crankshaft rotatably coupled to said piston, cylinder pressure and volume being related to each other with all valves closed by the equation PV.sup.γ
- =k wherein P is pressure, V is volume and γ and
k are constants, said apparatus comprisingmeans for monitoring angular rotation of said crankshaft, means for identifying an angular position θ
TDC of said crankshaft corresponding to top dead center of said piston within said cylinder,means for measuring pressure within said cylinder at a multiplicity of angularly spaced positions of said crankshaft while said crankshaft is rotating and said piston is reciprocating within said cylinder, means for identifying displacement volumes of said piston within said cylinder between at least some of said angularly spaced positions at which said valve is known to be closed, means for determining said constants γ and
k as a function of said displacement volumes and said measured pressures,means for comparing said measured pressures at the remainder of said angularly spaced positions to pressures P at said positions predicted by said equation, and means for identifying angle θ
V of valve operation with respect to θ
TDC as a function of a difference between said angularly spaced position.
- =k wherein P is pressure, V is volume and γ and
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10. A method of quantifying leakage within the cylinder of an internal combustion engine having a piston disposed to reciprocate in said cylinder and a crankshaft coupled to said piston, said method comprising the steps of:
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(a) monitoring angular rotation of said crankshaft, (b) identifying an angular positio θ
TDC of said crankshaft corresponding to top dead center of said piston within said cylinder,(c) measuring during the compression/power stroke of said piston cylinder pressures Pa, Pb, Pc at angularly spaced positions θ
a, θ
b, θ
c of said crankshaft different from said top dead center position θ
TDC,(d) measuring cylinder pressure Pd at angular position θ
d at preselected relationship to said angular position θ
TDC,(e) identifying volumes Va-b, Vb-c and Va-d of piston displacement between crankshaft positions θ
a, θ
b, θ
c and θ
d respectively,(f) determining the four unknowns Va , Vd, γ and
k as a function of the following four equations;
space="preserve" listing-type="equation">P.sub.a V.sub.a.sup.Γ
=k
space="preserve" listing-type="equation">P.sub.b (V.sub.a +V.sub.a-b).sup.γ
=k
space="preserve" listing-type="equation">P.sub.c (V.sub.a +V.sub.a-b +V.sub.b-c).sup.γ
=k
space="preserve" listing-type="equation">V.sub.d =V.sub.a-d(g) identifying a predicted pressure P'"'"'d at said crankshaft position θ
d as a function of the equation;
##EQU15## and then (h) quantifying cylinder leakage during said compression/power stroke as a function of a difference between P'"'"'d and Pd. - View Dependent Claims (21)
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11. A method of measuring angle of valve operation within the cylinder of an internal combustion engine having a piston disposed to reciprocate within said cylinder and a crankshaft rotatably coupled to said piston, cylinder pressure and volume being related to each other with all valves closed by the equation PV.sup.γ
- =k wherein P is pressure, V is volume and γ and
k are constants, said method comprising the steps of;(a) monitoring angular rotation of said crankshaft, (b) identifying an angular position θ
TDC of said crankshaft corresponding to top dead center of said piston within said cylinder,(c) measuring pressure within said cylinder at a multiplicity of angularly spaced positions of said crankshaft while said crankshaft is rotating and said piston is reciprocating within said cylinder, (d) identifying displacement volumes of said piston within said cylinder between at least some of said angularly spaced positions at which all said valves are known to be closed, (e) determining a volume V1 for at least one of said angularly spaced positions and said constants γ and
k as a function of said displacement volumes and said measured pressures,(f) determining said volume V for each of the remainder of said angularly spaced positions as a function of said volume V1 and engine design parameters, (g) comparing said measured pressures at said remainder of said angularly spaced positions to pressures P predicted by said equation, and (h) identifying angle θ
V of valve operation with respect to θ
TDC as a function of a difference between said predicted pressure and said measured pressure for each said angularly spaced position. - View Dependent Claims (12)
- =k wherein P is pressure, V is volume and γ and
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13. A method of measuring intake pressure P.sub.θ
- .sbsb.V within the cylinder of an internal combustion engi.ne having a piston disposed to reciprocate in said cylinder and a crankshaft coupled to said piston, said method comprising the steps of;
(a) monitoring angular rotation of said crankshaft, (b) identifying an angular position θ
TDC of said crankshaft corresponding to top dead center of said piston within said cylinder,(c) measuring cylinder pressure Pa, Pb, Pc , PTDC at angularly spaced positions θ
a, θ
b, θ
c, θ
TDC of said crankshaft,(d) identifying volumes Va-b and Vb-c of piston displacement between crankshaft positions θ
a, θ
b, θ
c,(e) determining at least cylinder parameter γ
as a function of the following three equations involving the three unknowns Va, γ and
k;
space="preserve" listing-type="equation">P.sub.a, γ
=k
space="preserve" listing-type="equation">P.sub.b (V.sub.a +V.sub.a-b).sup.γ
=k
space="preserve" listing-type="equation">P.sub.c (V.sub.a +V.sub.a-b +V.sub.b-c).sup. =k(f) identifying engine cylinder compression ratio C/R, and (g) determining cylinder intake pressure P.sub.θ
.sbsb.V as a function of the equation;
##EQU17##
- .sbsb.V within the cylinder of an internal combustion engi.ne having a piston disposed to reciprocate in said cylinder and a crankshaft coupled to said piston, said method comprising the steps of;
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14. A method of measuring intake pressure P.sub.θ
- .sbsb.V within the cylinder of an internal combustion engine having a piston disposed to reciprocate in said cylinder and a crankshaft coupled to said piston, said method comprising the steps of;
(a) monitoring angular rotation of said crankshaft, (b) measuring cylinder pressure Pa, Pb, Pc at angularly spaced positions θ
a, θ
b, θ
c of said crankshaft,(c) identifying volumes Va-b and Vb-c of piston displacement between crankshaft positions θ
a, θ
b, θ
c,(d) determining at least volume Va and cylinder parameter γ
as a function of the following three equations involving the three unknowns Va, γ and
k;
space="preserve" listing-type="equation">P.sub.a V.sub.a.sup.γ
=k
space="preserve" listing-type="equation">P.sub.b (V.sub.a +V.sub.a-b).sup.γ
=k
space="preserve" listing-type="equation">P.sub.c (V.sub.a +V.sub.a-b +V.sub.b-c).sup.γ
=k(e) identifying a volume V.sub.θ
.sbsb.V of said cylinder corresponding to intake valve closure, and(f) determining cylinder intake pressure P.sub.θ
.sbsb.V as a function of the equation;
##STR1##
- .sbsb.V within the cylinder of an internal combustion engine having a piston disposed to reciprocate in said cylinder and a crankshaft coupled to said piston, said method comprising the steps of;
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15. A method of quantifying leakage from a cylinder of an internal combustion engine having a piston disposed to reciprocate within said cylinder and a crankshaft rotatably coupled to said piston, said method comprising the steps of:
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(a) monitoring rotation of said crankshaft, (b) monitoring pressure within said cylinder while said crankshaft is rotating and said piston is reciprocating within said cylinder, (c) identifying displacement volumes of said piston within said cylinder as a function of rotation of said crankshaft, and (d) quantifying leakage from said cylinder as a function of monitored pressure and identified displacement volumes. - View Dependent Claims (16, 17, 18, 19, 20, 22, 23)
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24. Apparatus for quantifying leakage from a cylinder having a piston disposed to reciprocate therein and a shaft rotatably coupled to said piston, said apparatus comprising,
means for measuring pressure within said cylinder at a of spaced positions of said piston within said cylinder while said piston reciprocates within said cylinder, means for determining displacement volumes of said piston within said cylinder between said plurality of spaced positions, and means for quantifying leakage from said cylinder as a function of measured pressure and said displacement volumes.
Specification