How Rudolf Diesel's Engine Works
Rudolf Diesel's 1898 patent describes a highly efficient engine that ignites fuel using the heat generated by compressing air rather than using a spark plug.
Original patent title: “Internal-combustion engine”
Rudolf Diesel's 1898 patent describes a highly efficient engine that ignites fuel using the heat generated by compressing air rather than using a spark plug. Granted to Rudolf Diesel in 1898 with 10 forward citations.
Key facts
Coverage
What does this patent actually cover?
The engine operates by drawing in air and compressing it to such a high pressure that the temperature rises significantly. Once the air is hot enough, fuel is injected directly into the cylinder. The fuel ignites spontaneously upon contact with the superheated air, eliminating the need for an external ignition source like a spark plug.
The gap
What does this patent NOT cover?
- Does not cover engines that use spark plugs for ignition.
- Does not cover engines that mix fuel and air before compression.
- Does not cover external combustion engines like steam engines.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
Instead of trying to ignite a fuel-air mixture with a spark, Diesel used the laws of thermodynamics to turn the compression stroke itself into the ignition source.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Modern semi-truck engines
Diesel-powered locomotives
Marine ship propulsion systems
Construction equipment like excavators
Why it matters
The bigger picture
This invention fundamentally changed transportation by creating a more efficient alternative to the gasoline engine. It enabled the development of heavy machinery, long-haul trucking, and maritime shipping by providing superior torque and fuel economy.
Granted
August 9, 1898
Market context
Who's building on this
Companies in this space
Major automotive and industrial manufacturers like Cummins, Caterpillar, and Daimler continue to refine the core principles of compression ignition to meet modern emissions standards.
Market impact
This patent laid the foundation for the global logistics industry by making heavy-duty transport economically viable. It shifted the world away from steam power and established the diesel cycle as the standard for high-torque, heavy-load applications.
Claim 1 — Plain English
What this patent covers
The engine operates by drawing in air and compressing it to such a high pressure that the temperature rises significantly. Once the air is hot enough, fuel is injected directly into the cylinder. The fuel ignites spontaneously upon contact with the superheated air, eliminating the need for an external ignition source like a spark plug.
The clever bit
Instead of trying to ignite a fuel-air mixture with a spark, Diesel used the laws of thermodynamics to turn the compression stroke itself into the ignition source.
What it does not cover
- Does not cover engines that use spark plugs for ignition.
- Does not cover engines that mix fuel and air before compression.
- Does not cover external combustion engines like steam engines.
PatentBrief Score
Impact Score
Early stage
Citation count
21/40
Early citations
Claim breadth
0/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$5K – $15K
Midpoint $10K · expired or expiring · industry baseline
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Concepts involved
Citations
Patent lineage
Cite this patent
(1898). How Rudolf Diesel's Engine Works (U.S. Patent No. 608,845). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/608845/diesel-engine
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Rudolf Diesel's Engine Works cover?
Rudolf Diesel's 1898 patent describes a highly efficient engine that ignites fuel using the heat generated by compressing air rather than using a spark plug.
Who owns patent US 608845?
Rudolf Diesel owns this patent, granted in 1898.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 608845 cited by?
This patent has been cited by 10 later patents that build on its ideas.
What problem does this patent solve?
This invention fundamentally changed transportation by creating a more efficient alternative to the gasoline engine. It enabled the development of heavy machinery, long-haul trucking, and maritime shipping by providing superior torque and fuel economy.
What does this patent NOT cover?
Does not cover engines that use spark plugs for ignition.
Patent monitoring