Tuned battery pack damper for a hybrid electric vehicle

• US 7,734,384 B2
• Filed: 09/05/2006
• Issued: 06/08/2010
• Est. Priority Date: 09/05/2006
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Ledger, David, Konopa, Jason, Boismier, Jeffrey, Dolan, George, Cadwell, Floyd
• Primary Examiner(s): Tran; Dalena
• Application Number:
  US11/469,982
• Publication Number:
  US 20080059012A1
• Time in Patent Office: 1,372 Days
• Field of Search: 701/22, 180/68.5, 180/65.1, 180 656- 658, 429/96, 248/500, 248/503
• US Class Current: 701/22
• CPC Class Codes: B60G 13/16 having dynamic absorbers as main damping means, i.e. spring-mass system vibrating out of phase
• CPC Class Codes: B60G 2202/25 Dynamic damper
• CPC Class Codes: B60G 2204/20 Mounting of accessories, e.g. pump, compressor
• CPC Class Codes: B60G 2300/50 Electric vehicles; Hybrid vehicles
• CPC Class Codes: B60K 1/04 of the electric storage means for propulsion exchanging batteries for electric propulsion of vehicles B60L53/80; for auxiliary purposes only B60R16/04; supplying batteries to, or removing batteries from, vehicles B60S5/06
• CPC Class Codes: B60K 6/28 characterised by the electric energy storing means, e.g. batteries or capacitors
• CPC Class Codes: F16F 7/1028 the inertia-producing means being a constituent part of the system which is to be damped

Abstract

A tuned mass damper system and vibration damper method for a hybrid electric road vehicle is disclosed. The vehicle has a powertrain with an engine, at least one electric machine and a battery. The battery mass forms a part of a vehicle vibration absorber that attenuates vibrations induced by road wheels of the vehicle.

Claims

1. A tuned mass damper system for a hybrid electric road vehicle having road wheels and a powertrain with an engine, at least one motor-generator and a battery, the battery being a source of driving power and an electric energy storage medium, the damper system comprising:

a primary damper mass comprising the mass of the vehicle including mass of a vehicle body;

a secondary damper mass comprising the mass of the battery;

the secondary damper mass being spring-mounted on the primary damper mass;

the primary damper mass being substantially greater than the secondary damper mass, the primary damper mass and the secondary damper mass being in substantial vertical alignment and vertical motion of the secondary mass being out of phase with respect to the motion of the primary mass;

a vehicle suspension system located between the vehicle wheels and the vehicle mass, the suspension system supporting the vehicle mass;

the vehicle suspension system comprising at least one spring and at least one vibration damper acting in parallel relationship; and

at least one battery mounting spring between the battery mass and the vehicle mass and supporting the battery whereby the battery mass functions as a tuned damper mass as forced vibrations induced by road irregularities are attenuated as they are transmitted through the vehicle suspension system to the vehicle mass by the road wheels.

2. The tuned mass damper system for a hybrid electric road vehicle set forth in claim 1 wherein the battery mass is supported on the vehicle mass by multiple battery mounting springs at selected locations on the battery mass.

3. The tuned mass damper system for a hybrid electric road vehicle set forth in claim 1 wherein the road vehicle has front road engaging wheels and rear road engaging wheels;

the vehicle suspension system including separate spring and vibration damper subassemblies at the front road engaging wheels and the rear road engaging wheels.

4. A method for attenuating vibrations induced by vehicle road wheel forces that act on a hybrid electric road vehicle, the vehicle having a powertrain that includes an engine, an electric machine and a battery electrically coupled to the electric machine;

mounting the mass of the vehicle on vehicle road wheels with at least one suspension spring and damper assembly;

mounting the mass of the battery on the vehicle mass with at least one tuned mounting element;

calculating simplified equations of motion of the mass of the vehicle and the mass of the battery;

transforming the equation of motion of the mass of the vehicle from a time domain to a frequency domain;

transforming the equation of motion of the mass of the battery from a time domain to a frequency domain;

combining the transformed equations of motion of the vehicle mass and the battery mass; and

calculating an effective stiffness factor for the mounting spring for the mass of the battery using the combined transformed equations of motion.

5. The method set forth in claim 4 wherein the steps for transforming the equations of motion for the mass of the vehicle and the mass of the battery comprise developing a Laplace transform for each of the equations of motion.

6. The method set forth in claim 5 wherein the Laplace transforms for the equations of motion of the vehicle mass and the battery mass are:

$\left({\mathrm{Ms}}^2+K+\mathrm{Bs}+k\right)<br><br>x<br><br>\left(s\right)-\mathrm{kY}<br><br>\left(s\right)=\left(K+\mathrm{Bs}\right)<br><br>D<br><br>\left(s\right),\mathrm{and}$ $Y<br><br>\left(s\right)=\mathrm{kX}<br><br>\left(s\right)/\left({\mathrm{ms}}^2+k\right),$

where;

s=jω

,

ω

=frequency,

j=√

{square root over (−

1)}, an imaginary number,

M=vehicle mass,

D=vehicle mass displacement, and

Y=displacement of battery mass.

7. The method set forth in claim 4 wherein the simplified equation of motion of the vehicle mass is:

$M<br><br>\stackrel{\mathrm{¨<br><br>}}{x}+\mathrm{Kx}+B<br><br>\stackrel{.}{x}+\mathrm{kx}-\mathrm{ky}=\mathrm{Kd}+B<br><br>\stackrel{.}{d},$

where;

B=vehicle suspension damping, (force/velocity),

d=displacement input at the vehicle wheels,

k=hybrid battery mount stiffness, (force/displ.)=mω

² where ω

=frequency,

K=vehicle suspension stiffness (force/displ.),

m=hybrid battery mass,

M=vehicle mass,

x=displacement output of vehicle body, and

y=displacement of hybrid battery.

8. The method set forth in claim 7 wherein:

the equation of motion of the battery mass is

$m<br><br>\stackrel{\mathrm{¨<br><br>}}{y}+\mathrm{ky}-\mathrm{kx}=0.$

where;

k=hybrid battery mount stiffness, (force/displ.),

m=hybrid battery mass,

x=displacement output of vehicle body, and

y=displacement of hybrid battery.

9. The method set forth in claim 8 wherein a spring stiffness for the battery mass mounting spring is calculated by combining the transformed equations of motion of the vehicle mass and the battery mass in accordance with the equation:

$\frac{X<br><br>\left(\mathrm{j\omega <br><br>}\right)}{D<br><br>\left(\mathrm{j\omega <br><br>}\right)}=\left[\frac{\left(K+B<br><br><br><br>\mathrm{j\omega <br><br>}\right)<br><br>\left(-m<br><br><br><br>{\mathrm{\omega <br><br>}}^2+k\right)}{\left(-m<br><br><br><br>{\mathrm{\omega <br><br>}}^2+k\right)<br><br>\left(-M<br><br><br><br>{\mathrm{\omega <br><br>}}^2+B<br><br><br><br>\mathrm{j\omega <br><br>}+K+k\right)-k^2}\right];<br><br>\mathrm{and}$

computing a stiffness factor for the battery mass mounting spring by setting the term (−

mω

²+k) equal to zero in the combined transformed equations whereby the amplitude of vibrations discernable in the vehicle are minimized

where;

s=jω

,

ω

=frequency, and

j=√

{square root over (−

1)}, an imaginary number.

10. The method set forth in claim 4 wherein the equation of motion of the battery mass is

$m$

y ¨

+ ky - kx = 0 ,

where;

k=hybrid battery mount stiffness, (force/displ.),

m=hybrid battery mass,

x=displacement output of vehicle body, and

y=displacement of hybrid battery.