US 4589389

Here is a concise summary of US patent 4589389:

• Title: Fuel injection control apparatus for internal combustion engines
• Assignee: Hitachi Ltd.
• Inventors: Tokuo Kosuge, Kimiji Karino
• Filing Date: June 12, 1985
• Issue Date: May 20, 1986
• Abstract: The patent describes a fuel injection control apparatus for internal combustion engines. It determines a base injection pulse based on engine revolutions and intake air quantity. This base pulse is then calibrated using the formula T.sub.i =T.sub.p (1+K.sub.a +K.sub.b), where T.sub.i is the calibrated injection pulse width (determining injection time), T.sub.p is the base injection pulse width, K.sub.a is a calibration coefficient for acceleration level, and K.sub.b is an additional calibration coefficient for the level of deceleration that occurred before the acceleration.

Plain-Language Overview of Independent Claim 1:

Claim 1: This claim describes a fuel injection control system for an engine. This system first calculates a basic amount of fuel to inject (a "base injection pulse") based on the engine's current operating conditions. When the engine is slowing down (decelerating), the amount of fuel injected is significantly reduced or even stopped. However, if the engine then speeds up again (re-accelerates) immediately after this deceleration, the system not only adjusts the fuel for the current acceleration level (a "regular acceleration enrichment") but also adds an extra amount of fuel (an "additional acceleration enrichment"). This extra fuel amount is specifically determined by how intense the preceding deceleration was. This aims to prevent the air-fuel mixture from becoming too lean due to dried manifold walls after a significant deceleration.

CAFC 2026 Dockets:
A search of the U.S. Court of Appeals for the Federal Circuit (CAFC) dockets for the year 2026 did not yield any specific case filings or scheduled arguments pertaining to patent number US4589389. The patent itself expired due to non-payment of maintenance fees on May 20, 1998.

After conducting a thorough search for litigation involving US patent 4589389, no known litigation was found. The patent "US4589389A - Fuel injection control apparatus for internal combustion engines" appears to have expired due to non-payment of maintenance fees as of May 20, 1998.

Proceedings overview

There are no AIA trial proceedings on file for US patent 4589389 as of the most recent data ingest and web search. This indicates a defensive posture where the patent's claims remain untested by the PTAB's validity challenges.

Strategic summary

Given that there are no AIA trial proceedings on file for US patent 4589389, all four claims (claims 1-4) of the patent are currently untested by inter partes review (IPR), post-grant review (PGR), or covered business method (CBM) proceedings. This means no claims have been canceled or sustained by a PTAB Final Written Decision.

The absence of PTAB proceedings implies that the estoppel provisions of 35 U.S.C. § 315(e)(2) do not apply to this patent. Therefore, any potential defendant currently facing assertion of US4589389 would not be barred from raising any prior art grounds that could have been raised in an IPR. All statutory bases for challenging patentability (e.g., novelty under § 102, obviousness under § 103, subject matter eligibility under § 101, written description/enablement under § 112) remain fully available in district court litigation or in a newly filed PTAB petition, assuming statutory and regulatory requirements are met.

There is no pattern of PTAB activity to analyze, as no proceedings have been initiated. The absence of PTAB challenges for a patent granted in 1986 (and now expired) is not unusual, as AIA trials were introduced much later.

Recommended next steps

Since there are no PTAB proceedings on file for US patent 4589389, there are no active trials, institution decision deadlines, or FWD due dates to monitor. The patent expired on June 12, 2005.

For a defendant facing assertion of this patent (which is unlikely given its expired status), the primary implication is that the claims have not been subject to the accelerated, lower-burden validity challenges available through PTAB. If litigation were to arise, a defendant would have the full range of invalidity arguments available, unencumbered by PTAB estoppel.

Inventors

• Tokuo Kosuge (Hitachi Ltd.)
• Kimiji Karino (Hitachi Ltd.)

No unusual patterns observed regarding inventor departures.

Original assignee

Hitachi Ltd. is the original assignee. Hitachi is a multinational conglomerate primarily engaged in electronics, electrical equipment, and machinery manufacturing. They have historically shipped products embodying fuel injection control systems. Hitachi Ltd. is currently an operating company.

Assignment timeline

The USPTO Assignment Center shows the following record for US patent 4589389:

• 1985-07-02 (executed) / recorded 1986-01-07 — Reel 004493/0296
  • Conveyance: Assignment
  • Assignor: Kosuge, Tokuo; Karino, Kimiji
  • Assignee: HITACHI, LTD., 6, KANDA SURUGADAI 4-CHOME, CHIYODA-KU, TOKYO, JAPAN, A CORP. OF JAPAN
  • Correspondent: Not recorded.
  • Context: This is the initial assignment from the inventors to the original corporate assignee.

No other assignments for US4589389 are recorded in the USPTO Assignment Center.

Timeline diagram

timeline
    title Ownership of US 4589389
    1985 : Assigned to Hitachi Ltd
    1986 : Issued
    2005 : Patent expired

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The sole recorded assignment is from the inventors to Hitachi Ltd., an operating company.
2. Known asserter in the chain — not present. Hitachi Ltd. is not identified as a known NPE.
3. Repeat correspondent across the chain — not present. Correspondent information is not recorded for the single assignment.
4. Cascading transfers — not present. Only one assignment is recorded.
5. Pre-litigation transfer — not present. The patent has expired, and no litigation is associated with it in the assignment records.
6. Bankruptcy fire-sale — not present. There is no indication of Hitachi Ltd. filing for bankruptcy and selling this patent.
7. Privateering — not present. The patent remains with the original operating company assignee.
8. Defensive aggregator (anti-NPE) — not present. The patent remains with Hitachi Ltd. and has not been transferred to a defensive aggregator.

Verdict

Insufficient data. The only recorded assignment is from the inventors to the original operating company, Hitachi Ltd., on 1985-07-02 (Reel 004493/0296). There is no subsequent assignment information to suggest any NPE activity. The patent has expired as of 2005-06-12.

https://assignmentcenter.uspto.gov/

As a technical patent analyst, I have analyzed US patent 4589389, "Fuel injection control apparatus for internal combustion engines." The patent was filed on June 12, 1985, and published on May 20, 1986. Its core innovation lies in providing an "additional acceleration enrichment" of fuel when an engine accelerates immediately after a period of deceleration, with this additional enrichment being proportional to the severity (level) of the preceding deceleration. This mechanism aims to counteract the lean fuel mixture condition caused by a dry manifold wall after deceleration, which is a problem for single-point injection systems where fuel film storage evaporates during deceleration.

The following are the most relevant patent citations, as identified in US4589389's "Citations" section, along with their details and potential anticipation analysis under 35 U.S.C. § 102:

Prior Art Analysis for US4589389

1. US4311123A: Method and apparatus for controlling the fuel supply of an internal combustion engine

• Full Citation: US4311123A, Robert Bosch Gmbh, "Method and apparatus for controlling the fuel supply of an internal combustion engine"
• Filing Date: 1978-01-17
• Publication Date: 1982-01-19
• Brief Description: This patent generally describes a method and apparatus for controlling fuel supply to an internal combustion engine. It focuses on adapting the fuel supply based on engine operating conditions. Without specific details of its acceleration/deceleration logic beyond a general control, it is understood to represent the broader field of fuel injection control.
• Potential Anticipation: This patent likely anticipates the general concept of regulating fuel based on engine conditions, which forms the "base amount of an fuel to be injected... obtained in accordance with fundamental parameters" as described in claim 1 of US4589389. However, it does not appear to teach the specific "additional acceleration enrichment means for further calibrating the amount of the fuel to be injected in response to the level of the deceleration preceding to the re-acceleration," which is the distinguishing feature of US4589389. Therefore, it primarily anticipates the preamble of Claim 1, but not the novel "characterized by" clause. Claims 2, 3, and 4, which further define this specific enrichment, would also not be anticipated.

2. US4325341A: Fuel control device for fuel injection system for internal combustion engine

• Full Citation: US4325341A, Hitachi, Ltd., "Fuel control device for fuel injection system for internal combustion engine"
• Filing Date: 1978-11-06
• Publication Date: 1982-04-20
• Brief Description: This patent relates to a fuel control device for fuel injection systems, likely addressing issues such as air-fuel ratio control during various engine operations. As a Hitachi patent, it is from the same assignee as US4589389, indicating a continuous development in the field.
• Potential Anticipation: Similar to US4311123A, this patent likely anticipates aspects of general fuel control and base injection pulse determination (preamble of claim 1). Without specific disclosure of an "additional acceleration enrichment" linked to prior deceleration levels, it would not anticipate the novel elements of US4589389 in claims 1-4.

3. US4452212A: Fuel supply control system for an internal combustion engine

• Full Citation: US4452212A, Nissan Motor Co., Ltd., "Fuel supply control system for an internal combustion engine"
• Filing Date: 1981-01-26
• Publication Date: 1984-06-05
• Brief Description: This patent describes a fuel supply control system for an internal combustion engine. It likely deals with optimizing fuel delivery under different driving conditions, including transitions like acceleration and deceleration.
• Potential Anticipation: This patent would generally cover the control of fuel supply, including potentially reducing fuel during deceleration and providing enrichment during acceleration. These are common aspects of fuel injection systems mentioned in the background of US4589389. However, the unique "additional acceleration enrichment" based on preceding deceleration level (as defined in the "characterized by" clause of claim 1 and further detailed in claims 2-4 of US4589389) is not explicitly disclosed in the provided summary, and without the full text, it is not deemed to anticipate this specific inventive step. It likely anticipates the general concepts in the preamble of Claim 1.

4. US4414941A: Method and apparatus for fuel injection in electronic fuel injection controlled engines

• Full Citation: US4414941A, Toyota Jidosha Kogyo Kabushiki Kaisha, "Method and apparatus for fuel injection in electronic fuel injection controlled engines"
• Filing Date: 1981-08-07
• Publication Date: 1983-11-15
• Brief Description: This patent describes a method and apparatus for fuel injection in electronically controlled engines. This generally covers various aspects of electronic fuel injection systems and their control.
• Potential Anticipation: This patent, like the others, would likely cover conventional methods of determining a base injection pulse and applying general acceleration enrichment. The background of US4589389 explicitly states that prior art acceleration enrichment concepts (e.g., SAE Technical Paper Series 800164 "Throttle Body Fuel Injection (TBI)-An Integrated Engine Control System") were known but insufficient for the specific problem addressed by the invention. Therefore, while this patent likely anticipates general fuel injection control and some form of acceleration enrichment (preamble of claim 1), it is not expected to teach the specific "additional acceleration enrichment" based on the preceding deceleration level as claimed in US4589389.

5. JPS5928029A: Electronic fuel injection controlling method of internal combustion engine

• Full Citation: JPS5928029A, Toyota Motor Corp, "Electronic fuel injection controlling method of internal combustion engine"
• Filing Date: 1982-08-06
• Publication Date: 1984-02-14
• Brief Description: This Japanese patent application describes an electronic fuel injection controlling method for internal combustion engines. Similar to the US patents, it addresses fuel control strategies for optimal engine performance.
• Potential Anticipation: As a general electronic fuel injection control method, JPS5928029A would likely cover aspects of base fuel injection and acceleration enrichments known at the time. However, based on the problem statement and solution provided in US4589389, this Japanese patent is unlikely to teach the specific feature of an "additional acceleration enrichment" determined by the level of preceding deceleration. Therefore, it anticipates the general elements of fuel control (preamble of claim 1) but not the novel "characterized by" clause or the dependent claims 2-4.

In summary, none of the cited prior art, based on their brief descriptions and the problem statement in US4589389, explicitly disclose the inventive step of an "additional acceleration enrichment" specifically responsive to the level of the deceleration preceding the re-acceleration. This unique feature, designed to re-wet a dry manifold wall, appears to be the novel contribution of US4589389, and thus the claims of US4589389 (particularly the "characterized by" clause of Claim 1, and subsequently Claims 2, 3, and 4) are not anticipated by the provided prior art. The prior art primarily anticipates the common elements of fuel injection control systems that form the background of the invention.

The obviousness of US patent 4589389 under 35 U.S.C. § 103 can be analyzed by considering combinations of prior art references and the motivation a person having ordinary skill in the art (POSA) would have to combine them. The core of the invention in US4589389 is the provision of an "additional acceleration enrichment" based on the level of deceleration preceding a re-acceleration, in addition to a "regular acceleration enrichment" that depends on the current re-acceleration level. This aims to prevent lean fuel mixtures and acceleration delays after severe decelerations that dry out the intake manifold walls. [cite: Original Patent Text - SUMMARY OF THE INVENTION]

Key Claim Elements of US4589389:

• Claim 1: A fuel injection control apparatus with a base injection pulse ($T_p$), reduced fuel during deceleration, and a regular acceleration enrichment ($K_a$) upon re-acceleration. It is "characterized by an additional acceleration enrichment means for further calibrating the amount of the fuel to be injected in response to the level of the deceleration preceding to the re-acceleration." [cite: Original Patent Text - Claim 1]
• Claim 2: The deceleration level is discriminated by the decreasing rate of the number of revolutions of the engine ($dN/dt$). [cite: Original Patent Text - Claim 2]
• Claim 3: The injecting time $T_i$ is expressed as $T_i = T_p(1+K_a+K_b)$, where $K_b$ is the calibration coefficient determined by the preceding deceleration level. [cite: Original Patent Text - Claim 3]
• Claim 4: At least one of the calibration coefficients $K_a$ and $K_b$ is compensated by the cooling water temperature. [cite: Original Patent Text - Claim 4]

Relevant Prior Art and Their Disclosures:

1. Bowler, "Throttle Body Fuel Injection (TBI)-An Integrated Engine Control System", SAE Technical Paper Series 800164, 1980: This non-patent literature is explicitly referenced in US4589389 as disclosing the "acceleration enrichment concept" to account for "manifold filling dynamics and the fuel film storage on the manifold walls." [cite: Original Patent Text - BACKGROUND OF THE INVENTION, 9] This teaches the concept of the "regular acceleration enrichment" ($K_a$).
2. US4184461A (Acceleration enrichment for closed loop control systems, 1980): This patent describes an acceleration enrichment feature that provides increased fuel during transient conditions by "sensing the rate of change of throttle angle" ($d\theta/dt$). It also teaches combining these enrichment pulses with basic fuel injection pulses to achieve a desired air/fuel ratio during "operator induced transients."
3. General Knowledge in the Art (as reflected in US4589389's Background):
   • The use of a base injection pulse ($T_p$) determined by fundamental engine parameters (like engine speed and intake air quantity) was standard practice. [cite: Original Patent Text - BACKGROUND OF THE INVENTION]
   • Reducing or stopping fuel injection during engine deceleration was a known measure to reduce hydrogen carbonate in exhaust gas and improve fuel consumption. [cite: Original Patent Text - BACKGROUND OF THE INVENTION]
   • A known problem in fuel injection systems, particularly those with injectors before the intake manifold branching point, was that during deceleration with fuel reduction/cut-off, the fuel film on manifold walls would evaporate, making the walls dry. Upon subsequent acceleration, this dry wall condition would lead to a temporarily lean air-fuel mixture, causing increased noxious exhaust components and acceleration delay. The patent explicitly states that existing "acceleration enrichment" (i.e., $K_a$) was "insufficient" to address this specific issue. [cite: Original Patent Text - BACKGROUND OF THE INVENTION]
   • Detecting engine operating conditions, including acceleration and deceleration, by measuring parameters like engine speed ($N$) and its rate of change ($dN/dt$) or throttle position ($\theta$) and its rate of change ($d\theta/dt$), was a known technique. [cite: Original Patent Text - Detailed Description] USPTO classifications (e.g., F02D41/12 for "Introducing corrections for particular operating conditions for deceleration") also indicate this as a recognized area of control. [cite: Original Patent Text - Classifications]
   • Temperature compensation (e.g., using cooling water temperature) for fuel injection was a common practice for optimizing engine operation, especially under cold conditions. [cite: Original Patent Text - Detailed Description]

Obviousness Analysis:

A combination of SAE Technical Paper 800164, US4184461A, and common general knowledge in the field would render the claims of US4589389 obvious to a POSA.

Motivation for Combination to Render Claim 1 Obvious:

A POSA, familiar with the teachings of Bowler (SAE 800164) regarding "regular acceleration enrichment" ($K_a$) for manifold fuel film compensation and US4184461A regarding the implementation of $K_a$ using throttle angle rate of change ($d\theta/dt$), would be well-versed in handling transient engine operations. The POSA would also be acutely aware of the widely recognized problem (as described in the background of US4589389) that, despite existing $K_a$ strategies, a lean mixture and acceleration delay still occurred when an engine was accelerated immediately after a period of deceleration where fuel was reduced or cut off. This problem was understood to be caused by the evaporation of fuel film, leaving the manifold walls excessively dry. [cite: Original Patent Text - BACKGROUND OF THE INVENTION]

Confronted with this known and persistent problem, a POSA would be motivated to further refine the acceleration enrichment strategy. Recognizing that the "degree of dryness of the manifold walls is closely related with the degree or level of the deceleration done precedingly to the acceleration" [cite: Original Patent Text - BACKGROUND OF THE INVENTION] (a logical deduction given the problem description), the POSA would be led to consider the history and severity of the preceding deceleration as a critical factor for additional fuel compensation.

Therefore, to solve this acknowledged deficiency of existing systems, a POSA would find it obvious to introduce an "additional acceleration enrichment means" that specifically takes into account the "level of the deceleration preceding to the re-acceleration." This directly leads to the subject matter of Claim 1.

Obviousness of Dependent Claims:

• Claim 2 (Deceleration Level by $dN/dt$): Once the need to quantify the "level of deceleration" is established (as motivated for Claim 1), using the decreasing rate of engine revolutions ($dN/dt$) to discriminate this level is a straightforward and conventional engineering choice. Engine speed and its rate of change were well-known parameters for detecting and assessing deceleration conditions in engine control systems. [cite: Original Patent Text - Detailed Description, Classifications]
• Claim 3 (Formula $T_i = T_p(1+K_a+K_b)$): Given the base injection pulse ($T_p$), and the concepts of both regular ($K_a$) and additional ($K_b$) acceleration enrichment coefficients, expressing the total injection time ($T_i$) as an additive or multiplicative combination of these factors with the base pulse is a routine mathematical implementation in control theory. The formula $T_p(1+K_a+K_b)$ represents a common and obvious way to apply these multiple correction factors.
• Claim 4 (Temperature Compensation): The application of temperature compensation to fuel injection, generally using cooling water temperature, was a well-established practice in the art to optimize fuel delivery across various thermal conditions. Applying this known optimization technique to either the regular ($K_a$) or additional ($K_b$) acceleration enrichment coefficients (or both) for further refinement is a matter of routine design, not an inventive step. [cite: Original Patent Text - Detailed Description]

In summary, the specific problem of dried manifold walls after deceleration leading to insufficient fuel upon subsequent acceleration was known. A POSA, seeking to solve this known problem, would be motivated to apply an additional enrichment that accounts for the severity of the prior deceleration. The methods for measuring deceleration, formulating the injection pulse, and compensating for temperature were all within the purview of a POSA at the time of the invention.