Patent US2661946A successfully refreshed from Google Patents.
Patent US5135070A successfully refreshed from Google Patents.
US5135070A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Active hydraulic pressure control
Assignee: Aura Systems Inc
•
Filing: 1991-07-30
•
Granted: 1992-08-04
•
Expires: 2011-07-30
Abstract
Abstract An active hydraulic pressure control system includes a sensor, a valve, a controller and an actuator. In accordance with a broad aspect of the present invention, the controller determines a pressure differential between the pressure sensed by the sensor in a high pressure supply line of a hydraulic system and a predetermined pressure. In response to such pressure differential, the actuator drives the valve which has a variable flow orifice to communicate hydraulic fluid between the high pressure supply line and a reservoir of hydraulic fluid to eliminate the pressure differential.
Inventors
- 👤 J. David Schwitalla
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 06:04
CPC Classifications
B; B60; B60G; B60G17/00; B60G17/015; B60G17/0195; B62; B62D; B62D5/00; B62D5/06; B62D5/09; B60G2202/00; B60G2202/40; B60G2202/41; B60G2202/413; B60G2400/00; B60G2400/25; B60G2400/50; B60G2400/60; B60G2500/00; B60G2500/40; B60G2600/00; B60G2600/60; B60G2600/602; B60G2600/604; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/86582; Y10T137/8659; Y10T137/87169
Claims Analysis
Total Claims: 76
Claim 1
Independent Claim
94 words
An active hydraulic pressure control system comprising: a sensor to sense pressure of hydraulic fluid within a high pressure supply line of a hydraulic power transmission system; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and a reservoir of hydraulic fluid; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 2
Dependent Claim
94 words
An active hydraulic pressure control system comprising: a sensor to sense pressure of hydraulic fluid within a high pressure supply line of a hydraulic power transmission system; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and a reservoir of hydraulic fluid; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 3
Dependent Claim
108 words
A system as set forth in claim 1 wherein said controller includes: a flow control circuit responsive to a sensed pressure electrical signal and a predetermined pressure electrical signal to develop a first command electrical signal as a function of each of said sensed pressure signal and said predetermined pressure signal; and a pinion control circuit responsive to said first command signal and a sensed actuator position electrical signal to develop a second command electrical signal as a function of each of said first command signal and said sensed actuator position signal, said second command signal being applied to said actuator to actuate said valve in response thereto.
Claim 4
Dependent Claim
62 words
A system as set forth in claim 2 wherein said flow control circuit includes: a subtracter to develop an error signal as a difference between said predetermined pressure signal and said sensed pressure signal; and a high pass filter to develop a first filtered electrical signal from said error signal, said first command signal being linearly commensurate with said first filtered signal.
Claim 5
Dependent Claim
64 words
A system as set forth in claim 3 wherein said flow control circuit further includes: an amplitude demodulator to develop a demodulated electrical signal from said filtered signal; a low pass filter to develop a second filtered signal from said demodulated signal; and a summer to develop said first command signal as a summation of said first filtered signal and said second filtered signal.
Claim 6
Dependent Claim
44 words
A system as set forth in claim 4 wherein said summer is further responsive to a second predetermined pressure electrical signal to develop said first command signal as a summation of said first filtered signal, said second filtered signal and said second pressure signal.
Claim 7
Dependent Claim
40 words
A system as set forth in claim 5 wherein said first pressure signal is commensurate with a predetermined dynamic pressure in said supply line, and said second pressure signal is commensurate with a predetermined static pressure in said supply line.
Claim 8
Dependent Claim
27 words
A system as set forth in claim 4 wherein said low pass filter has a cutoff frequency selected to remove high frequency noise from said demodulated signal.
Claim 9
Dependent Claim
29 words
A system as set forth in claim 3 wherein said high pass filter has a cutoff frequency above a desired bandwidth of hydraulic pressure in said power transmission system.
Claim 10
Dependent Claim
19 words
System as set forth in claim 2 wherein said sensor transduces hydraulic fluid pressure to said sensed pressure signal.
Claim 11
Dependent Claim
57 words
A system as set forth in claim 2 wherein said position control circuit includes: a subtracter to develop an error signal as a difference between said first command signal and said sensed position signal; and a compensator to develop a filtered signal from said error signal, said second command signal being linearly commensurate with said filtered signal.
Claim 12
Dependent Claim
30 words
A system as set forth in claim 10 wherein said position control circuit includes a power amplifier to which said filtered signal is applied to develop said second command signal.
Claim 13
Dependent Claim
27 words
A system as set forth in claim 10 wherein said position control circuit further includes: a position sensor to transduce actuator position to said sensed position signal.
Claim 14
Dependent Claim
35 words
A system as set forth in claim 10 wherein said compensator develops said filtered signal as a selected function of said error signal, said selected function being selected ones of proportional, integral and derivative functions.
Claim 15
Dependent Claim
16 words
A system as set forth in claim 1 wherein said actuator is an electromagnetic linear actuator.
Claim 16
Dependent Claim
128 words
For a hydraulic power transmission system wherein a pump supplies hydraulic fluid from a reservoir through a high pressure supply line to a hydraulic fluid actuated load and said fluid returns from said load through a low pressure return line to said reservoir, and active hydraulic pressure control system comprising: a sensor to sense pressure of hydraulic fluid within said high pressure supply line; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and said reservoir; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 17
Dependent Claim
128 words
For a hydraulic power transmission system wherein a pump supplies hydraulic fluid from a reservoir through a high pressure supply line to a hydraulic fluid actuated load and said fluid returns from said load through a low pressure return line to said reservoir, and active hydraulic pressure control system comprising: a sensor to sense pressure of hydraulic fluid within said high pressure supply line; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and said reservoir; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 18
Dependent Claim
108 words
A system as set forth in claim 15 wherein said controller includes: a flow control circuit responsive to a sensed pressure electrical signal and a predetermined pressure electrical signal to develop a first command electrical signal as a function of each of said sensed pressure signal and said predetermined pressure signal; and a position control circuit responsive to said first command signal and a sensed actuator position electrical signal to develop a second command electrical signal as a function of each of said first command signal and said sensed actuator position signal, said second command signal being applied to said actuator to actuate said valve in response thereto.
Claim 19
Dependent Claim
62 words
A system as set forth in claim 16 wherein said flow control circuit includes: a subtracter to develop an error signal as a difference between said predetermined pressure signal and said sensed pressure signal; and a high pass filter to develop a first filtered electrical signal from said error signal, said first command signal being linearly commensurate with said first filtered signal.
Claim 20
Dependent Claim
64 words
A system as set forth in claim 17 wherein said flow control circuit further includes: an amplitude demodulator to develop a demodulated electrical signal from said filtered signal; a low pass filter to develop a second filtered signal from said demodulated signal; and a summer to develop said first command signal as a summation of said first filtered signal and said second filtered signal.
Claim 21
Dependent Claim
44 words
A system as set forth in claim 18 wherein said summer is further responsive to a second predetermined pressure electrical signal to develop said first command signal as a summation of said first filtered signal, said second filtered signal and said second pressure signal.
Claim 22
Dependent Claim
40 words
A system as set forth in claim 19 wherein said first pressure signal is commensurate with a predetermined dynamic pressure in said supply line, and said second pressure signal is commensurate with a predetermined static pressure in said supply line.
Claim 23
Dependent Claim
27 words
A system as set forth in claim 20 wherein said low pass filter has a cutoff frequency selected to remove high frequency noise from said demodulated signal.
Claim 24
Dependent Claim
29 words
A system as set forth in claim 17 wherein said high pass filter has a cutoff frequency above a desired bandwidth of hydraulic pressure in said power transmission system.
Claim 25
Dependent Claim
20 words
A system as set forth in claim 16 wherein said sensor transduces hydraulic fluid pressure to said sensed pressure signal.
Claim 26
Dependent Claim
57 words
A system as set forth in claim 16 wherein said position control circuit includes: a subtracter to develop an error equal as a difference between said first command signal and said sensed position signal; and a compensator to develop a filtered signal from said error signal, said second command signal being linearly commensurate with said filtered signal.
Claim 27
Dependent Claim
30 words
A system as set forth in claim 24 wherein said position control circuit includes a power amplifier to which said filtered signal is applied to develop said second command signal.
Claim 28
Dependent Claim
27 words
A system as set forth in claim 24 wherein said position control circuit further includes: a position sensor to transduce actuator position to said sensed position signal.
Claim 29
Dependent Claim
35 words
A system as set forth in claim 24 wherein said compensator develops said filtered signal as a selected function of said error signal, said selected function being selected ones of proportional, integral and derivative functions.
Claim 30
Dependent Claim
16 words
A system as set forth in claim 15 wherein said actuator is an electromagnetic linear actuator.
Claim 31
Dependent Claim
125 words
For a hydraulic servo system wherein a pump supplies hydraulic fluid from a reservoir through a high pressure supply line to a hydraulic servo and said fluid returns from said servo through a low pressure return line to said reservoir, an active hydraulic pressure control system comprising: a sensor to sense pressure of hydraulic fluid within said high pressure supply line; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and said reservoir; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 32
Dependent Claim
125 words
For a hydraulic servo system wherein a pump supplies hydraulic fluid from a reservoir through a high pressure supply line to a hydraulic servo and said fluid returns from said servo through a low pressure return line to said reservoir, an active hydraulic pressure control system comprising: a sensor to sense pressure of hydraulic fluid within said high pressure supply line; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and said reservoir; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 33
Dependent Claim
108 words
A system as set forth in claim 29 wherein said controller includes: a flow control circuit responsive to a sensed pressure electrical signal and a predetermined pressure electrical signal to develop a first command electrical signal as a function of each of said sensed pressure signal and said predetermined pressure signal; and a position control circuit responsive to said first command signal and a sensed actuator position electrical signal to develop a second command electrical signal as a function of each of said first command signal and said sensed actuator position signal, said second command signal being applied to said actuator to actuate said valve in response thereto.
Claim 34
Dependent Claim
63 words
A system as set forth in claim 30 wherein said said flow control circuit includes: a subtractor to develop an error signal as a difference between said predetermined pressure signal and said sensed pressure signal; and a high pass filter to develop a first filtered electrical signal from said error signal, said first command signal being linearly commensurate with said first filtered signal.
Claim 35
Dependent Claim
64 words
A system as set forth in claim 31 wherein said flow control circuit further includes: an amplitude demodulator to develop a demodulated electrical signal from said filtered signal; a low pass filter to develop a second filtered signal from said demodulated signal; and a summer to develop said first command signal as a summation of said first filtered signal and said second filtered signal.
Claim 36
Dependent Claim
44 words
A system as set forth in claim 32 wherein said summer is further responsive to a second predetermined pressure electrical signal to develop said first command signal as a summation of said first filtered signal, said second filtered signal and said second pressure signal.
Claim 37
Dependent Claim
40 words
A system as set forth in claim 33 wherein said first pressure signal is commensurate with a predetermined dynamic pressure in said supply line, and said second pressure signal is commensurate with a predetermined static pressure in said supply line.
Claim 38
Dependent Claim
27 words
A system as set forth in claim 34 wherein said low pass filter has a cutoff frequency selected to remove high frequency noise from said demodulated signal.
Claim 39
Dependent Claim
29 words
A system as set forth in claim 31 wherein said high pass filter has a cutoff frequency above a desired bandwidth of hydraulic pressure in said hydraulic servo system.
Claim 40
Dependent Claim
20 words
A system as set forth in claim 30 wherein said sensor transduces hydraulic fluid pressure to said sensed pressure signal.
Claim 41
Dependent Claim
57 words
A system as set forth in claim 30 wherein said position control circuit includes: a subtracter to develop an error signal as a difference between said first command signal and said sensed position signal; and a compensator to develop a filtered signal from said error signal, said second command signal being linearly commensurate with said filtered signal.
Claim 42
Dependent Claim
30 words
A system as set forth in claim 38 wherein said position control circuit includes a power amplifier to which said filtered signal is applied to develop said second command signal.
Claim 43
Dependent Claim
27 words
A system as set forth in claim 38 wherein said position control circuit further includes: a position sensor to transduce actuator position to said sensed position signal.
Claim 44
Dependent Claim
35 words
A system as set forth in claim 38 wherein said compensator develops said filtered signal as a selected function of said error signal, said selected function being selected ones of proportional, integral and derivative functions.
Claim 45
Dependent Claim
16 words
A system as set forth in claim 29 wherein said actuator is an electromagnetic linear actuator.
Claim 46
Dependent Claim
147 words
For a hydraulic power steering assist system in a motor vehicle wherein said assist system has an engine driven hydraulic pump which supplies hydraulic fluid from a reservoir through a high pressure supply line to a hydraulic servo assist to act on a steering rack and said fluid returns from said servo assist through a low pressure return line to said reservoir, an active hydraulic pressure control system comprising: a sensor to sense pressure of hydraulic fluid within said high pressure supply line; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and said reservoir; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 47
Dependent Claim
147 words
For a hydraulic power steering assist system in a motor vehicle wherein said assist system has an engine driven hydraulic pump which supplies hydraulic fluid from a reservoir through a high pressure supply line to a hydraulic servo assist to act on a steering rack and said fluid returns from said servo assist through a low pressure return line to said reservoir, an active hydraulic pressure control system comprising: a sensor to sense pressure of hydraulic fluid within said high pressure supply line; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and said reservoir; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 48
Dependent Claim
108 words
A system as set forth in claim 43 wherein said controller includes: a flow control circuit responsive to a sensed pressure electrical signal and a predetermined pressure electrical signal to develop a first command electrical signal as a function of each of said sensed pressure signal and said predetermined pressure signal; and a position control circuit responsive to said first command signal and a sensed actuator position electrical signal to develop a second command electrical signal as a function of each of said first command signal and said sensed actuator position signal, said second command signal being applied to said actuator to actuate said valve in response thereto.
Claim 49
Dependent Claim
63 words
A system as set forth in claim 44 wherein said said flow control circuit includes: a subtracter to develop an error signal as a difference between said predetermined pressure signal and said sensed pressure signal; and a high pass filter to develop a first filtered electrical signal from said error signal, said first command signal being linearly commensurate with said first filtered signal.
Claim 50
Dependent Claim
64 words
A system as set forth in claim 45 wherein said flow control circuit further includes: an amplitude demodulator to develop a demodulated electrical signal from said filtered signal; a low pass filter to develop a second filtered signal from said demodulated signal; and a summer to develop said first command signal as a summation of said first filtered signal and said second filtered signal.
Claim 51
Dependent Claim
44 words
A system as set forth in claim 46 wherein said summer is further responsive to a second predetermined pressure electrical signal to develop said first command signal as a summation of said first filtered signal, said second filtered signal and said second pressure signal.
Claim 52
Dependent Claim
40 words
A system as set forth in claim 47 wherein said first pressure signal is commensurate with a predetermined dynamic pressure in said supply line, and said second pressure signal is commensurate with a predetermined static pressure in said supply line.
Claim 53
Dependent Claim
27 words
A system as set forth in claim 48 wherein said low pass filter has a cutoff frequency selected to remove high frequency noise from said demodulated signal.
Claim 54
Dependent Claim
30 words
A system as set forth in claim 45 wherein said high pass filter has a cutoff frequency above a desired bandwidth of hydraulic pressure in said power steering assist system.
Claim 55
Dependent Claim
20 words
A system as set forth in claim 44 wherein said sensor transduces hydraulic fluid pressure to said sensed pressure signal.
Claim 56
Dependent Claim
57 words
A system as set forth in claim 44 wherein said position control circuit includes: a subtracter to develop an error signal as a difference between said first command signal and said sensed position signal; and a compensator to develop a filtered signal from said error signal, said second command signal being linearly commensurate with said filtered signal.
Claim 57
Dependent Claim
30 words
A system as set forth in claim 52 wherein said position control circuit includes a power amplifier to which said filtered signal is applied to develop said second command signal.
Claim 58
Dependent Claim
27 words
A system as set forth in claim 52 wherein said position control circuit further includes: a position sensor to transduce actuator position to said sensed position signal.
Claim 59
Dependent Claim
35 words
A system as set forth in claim 52 wherein said compensator develops said filtered signal as a selected function of said error signal, said selected function being selected ones of proportional, integral and derivative functions.
Claim 60
Dependent Claim
16 words
A system as set forth in claim 43 wherein said actuator is an electromagnetic linear actuator.
Claim 61
Dependent Claim
168 words
A motor vehicle hydraulic power steering assist system comprising: a reservoir of hydraulic fluid; an engine driven hydraulic pump; a hydraulic servo assist to act on a steering gear of a motor vehicle; a high pressure supply line interconnected between said pump and said servo assist; a low pressure return line interconnected between said servo assist and said reservoir, said pump delivering hydraulic fluid from said reservoir to said servo assist through said supply line, hydraulic fluid being returned from said servo assist to said reservoir through said return line; a sensor to sense pressure of hydraulic fluid within said high pressure supply line; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and said reservoir; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 62
Dependent Claim
168 words
A motor vehicle hydraulic power steering assist system comprising: a reservoir of hydraulic fluid; an engine driven hydraulic pump; a hydraulic servo assist to act on a steering gear of a motor vehicle; a high pressure supply line interconnected between said pump and said servo assist; a low pressure return line interconnected between said servo assist and said reservoir, said pump delivering hydraulic fluid from said reservoir to said servo assist through said supply line, hydraulic fluid being returned from said servo assist to said reservoir through said return line; a sensor to sense pressure of hydraulic fluid within said high pressure supply line; a valve having a variable flow orifice, said orifice to communicate hydraulic fluid between said supply line and said reservoir; a controller responsive to the sensed pressure and a predetermined pressure to determine a pressure differential therebetween; and an actuator responsive to the pressure differential to actuate said valve so that hydraulic fluid flow through said orifice is varied to eliminate the pressure differential.
Claim 63
Dependent Claim
108 words
A system as set forth in claim 57 wherein said controller includes: a flow control circuit responsive to a sensed pressure electrical signal and a predetermined pressure electrical signal to develop a first command electrical signal as a function of each of said sensed pressure signal and said predetermined pressure signal; and a position control circuit responsive to said first command signal and a sensed actuator position electrical signal to develop a second command electrical signal as a function of each of said first command signal and said sensed actuator position signal, said second command signal being applied to said actuator to actuate said valve in response thereto.
Claim 64
Dependent Claim
63 words
A system as set forth in claim 58 wherein said said flow control circuit includes: a subtracter to develop an error signal as a difference between said predetermined pressure signal and said sensed pressure signal; and a high pass filter to develop a first filtered electrical signal from said error signal, said first command signal being linearly commensurate with said first filtered signal.
Claim 65
Dependent Claim
64 words
A system as set forth in claim 59 wherein said flow control circuit further includes: an amplitude demodulator to develop a demodulated electrical signal from said filtered signal; a low pass filter to develop a second filtered signal from said demodulated signal; and a summer to develop said first command signal as a summation of said first filtered signal and said second filtered signal.
Claim 66
Dependent Claim
44 words
A system as set forth in claim 60 wherein said summer is further responsive to a second predetermined pressure electrical signal to develop said first command signal as a summation of said first filtered signal, said second filtered signal and said second pressure signal.
Claim 67
Dependent Claim
40 words
A system as set forth in claim 61 wherein said first pressure signal is commensurate with a predetermined dynamic pressure in said supply line, and said second pressure signal is commensurate with a predetermined static pressure in said supply line.
Claim 68
Dependent Claim
27 words
A system as set forth in claim 62 wherein said low pass filter has a cutoff frequency selected to remove high frequency noise from said demodulated signal.
Claim 69
Dependent Claim
30 words
A system as set forth in claim 59 wherein said high pass filter has a cutoff frequency above a desired bandwidth of hydraulic pressure is said power steering assist system.
Claim 70
Dependent Claim
20 words
A system as set forth in claim 58 wherein said sensor transduces hydraulic fluid pressure to said sensed pressure signal.
Claim 71
Dependent Claim
57 words
A system as set forth in claim 58 wherein said position control circuit includes: a subtracter to develop an error signal as a difference between said first command signal and said sensed position signal; and a compensator to develop a filtered signal from said error signal, said second command signal being linearly commensurate with said filtered signal.
Claim 72
Dependent Claim
30 words
A system as set forth in claim 66 wherein said position control circuit includes a power amplifier to which said filtered signal is applied to develop said second command signal.
Claim 73
Dependent Claim
27 words
A system as set forth in claim 66 wherein said position control circuit further includes: a position sensor to transduce actuator position to said sensed position signal.
Claim 74
Dependent Claim
35 words
A system as set forth in claim 66 wherein said compensator develops said filtered signal as a selected function of said error signal, said selected function being selected ones of proportional, integral and derivative functions.
Claim 75
Dependent Claim
57 words
A system as set forth in claim 58 where said actuator is a linear electromagnetic actuator having a core and a coil to which said second command signal is applied, said coil being mechanically coupled to said valve to actuate said valve, said coil being displaced in linear proportionality to said second command signal when applied thereto.
Claim 76
Dependent Claim
137 words
A system as set forth in claim 70 wherein said valve is a spool valve having a valve body and a spool, said valve body having a cylindrical bore closed at one end thereof, an inlet opening to communicate hydraulic fluid from said supply line to said bore and an outlet opening to communicate hydraulic fluid from said bore to said reservoir, said spool being received in axially slideable engagement within said bore and having an annular channel, said channel, said inlet opening and said outlet opening each being disposed with respect to each other such that during axial movement of said spool along its total stroke said inlet opening communicates with said bore through said annular channel and said annular channel is varied in communication with said outlet opening to vary flow of hydraulic fluid therethrough.
References Cited (Backward Citations)
US3692137A
Cited
US3870077A
Cited
US4632638A
Cited
US4694927A
Cited
US4757980A
Cited
US4899842A
Cited
US4926906A
Cited
US4912343A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-08-04 | 1996-02-03 | 1996-08-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-08-04 | 2000-02-03 | 2000-08-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-08-04 | 2004-02-03 | 2004-08-04 | $7700.00 | Window Closed / Lapsed |