Heat Pump Clothes Dryer Cycle Design Patents: Leaders & Trends 2026
- Five filers hold 63.3% of the field. 76 of 120 records in scope sit with the top five assignees, leaving a long tail of single- or few-filing entrants competing for the remainder.
- Cycle-transient and frosting claims trail drying-time claims by a wide margin. D06F drying/laundering classifications cover 86.7% of records while F25B refrigeration-cycle classifications cover only 8.3%, pointing to where cycle-level claim space is thinner.
- Filing has cooled from its 2017 peak of six records a year. The three-year span from 2021 to 2024 shows a 67% drop, though 2025-2026 figures are still incomplete because publication lags filing by about 18 months.
Filing growth compares 2021 (3 records) with 2024 (1) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 120 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Heat pump clothes dryer cycle design sits at the intersection of laundry appliance engineering and small-scale refrigeration control: compressor sizing, evaporator frosting management, refrigerant charge, and the transient behaviour of the cycle as a load dries. This landscape draws on 120 published records filed between 2015 and mid-2026 that reference heat pump clothes dryers or dryer refrigeration cycles alongside at least one of compressor sizing, evaporator frosting, drying time, energy label performance, refrigerant charge, or cycle transients. Patent families, not raw document counts, are the fairer unit for judging how crowded any one sub-area actually is.
Filing activity is concentrated among appliance manufacturers with existing heat pump dryer product lines, and the record set spans receiving offices in the United States, China, Europe, India, Japan and Germany. The technology composition below shows most records classified under laundering and drying rather than refrigeration itself, which is a useful signal for where claim space is thin.
Filing trend and technology composition
The two views below cover the same 120 records from different angles: one tracks filing activity over time, the other shows how records are classified across IPC subclasses.
Filing trend, 2017-2026
Filings peaked at 6 records in 2017 and have declined since; the 2021-to-2024 span shows a 67% drop (3 to 1 records). The most recent one to two years are understated because publication typically lags filing by around 18 months, so 2025 and 2026 should not be read as a continued decline yet.
Technology composition by IPC subclass
D06F (laundering, drying and ironing) covers 86.7% of the 120 records in scope and F26B (drying) covers 40.8%, confirming this is primarily an appliance-and-drying-process field. F25B (refrigeration and heat pumps) appears in only 8.3% of records, with F25D, F04C, A47L, F24F and F24H each under 3%. Because records can carry multiple classes, these shares add up to more than 100% and should be read against the 120-record total, not against each other.
Shares are the percentage of the 120 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Heat Pump Clothes Dryer Cycle Design with Eureka
This page is one run against one query. Ask Eureka your own question about heat pump clothes dryer cycle design and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative and most-cited filings
Apparatus and method for refrigerant cycle capacity acceleration (US8528227B2)
The patent describes partitioning available energy in a heat pump clothes dryer into a portion that maintains standard performance and a second portion used to energise an auxiliary heater during the start transient phase, accelerating the dry cycle beyond what the base refrigeration cycle alone would deliver.Filed by Haier US Appliance Solutions; granted 2013-09-10.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20050066538A1 | Heat pump clothes dryer | 282 |
| 2 | US7055262B2 | Heat pump clothes dryer | 207 |
| 3 | US20060179676A1 | Heat pump clothes dryer | 148 |
| 4 | US7665225B2 | Heat pump clothes dryer | 91 |
| 5 | US7020985B2 | Multiple outlet air path for a clothes dryer | 79 |
| 6 | US20140366397A1 | Clothes dryer | 55 |
| 7 | US20120102779A1 | Apparatus and method for refrigeration cycle elevation by modification of cycle start condition | 44 |
| 8 | WO2005032322A2 | Heat pump clothes dryer | 41 |
| 9 | US8572865B2 | Apparatus and method for using a hybrid dryer tub for airflow improvement | 35 |
| 10 | US8601717B2 | Apparatus and method for refrigeration cycle capacity enhancement | 30 |
Citation counts favour older filings simply because they have had more time to be cited within this searched corpus; treat them as a signal of influence on later work, not of current commercial importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns stand out once concentration, classification and citation data are read together.
The field has a narrow leading group and a long tail
Five assignees hold 76 of the 120 records in scope, and the top ten extend that to 94.2%. That leaves very little filing activity outside a small set of established appliance manufacturers, so a new entrant is filing directly against incumbents rather than into open ground.
Drying-process claims dominate over refrigeration-cycle claims
D06F laundering and drying classifications appear in 86.7% of records while F25B refrigeration and heat pump classifications appear in only 8.3%. Claim writers have concentrated on drying process and control, leaving the refrigeration-cycle mechanics of the same appliance comparatively open.
Recorded filing has slowed, but the most recent years are incomplete
The three-year span from 2021 to 2024 that can be treated as complete shows a drop from 3 to 1 records. Because publication lags filing by roughly 18 months, 2025 and 2026 counts will keep rising as more filings publish, so this should be read as the last confirmed trend point rather than the current state.
Filing is spread across three major offices rather than one
The United States (30), China (25) and the European Patent Office (20) each carry a meaningful share of records, with India, Japan and Germany each in single digits. Any freedom-to-operate check needs to clear all three major offices rather than treating one as dominant.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to heat pump clothes dryer cycle design, with the prior art for and against each one.
Who is filing, and where the gate sits
The ranking below covers the 34 companies the data endpoint returns for this search, ordered by record count. It is not a top-50 or top-100 list — it is the whole ranked field.
One filer sits well ahead of the rest of the ranking
The leading assignee holds 18 records, roughly 40% more than the record count at fifth place. That gap suggests a company with a sustained, multi-generation product programme rather than a single filing burst.
Co-assignee pairs cluster around a small number of inventor teams
The strongest co-assignee pairings recur at a count of 10, which points to stable internal engineering teams or parent-subsidiary filing arrangements rather than one-off joint ventures.
Almost nothing is filed outside the top ten assignees
With 113 of 120 records held by ten companies, an entrant outside that group is filing into a field where nearly every prior record already belongs to an established player. Differentiation has to come from a specific technical angle, not from volume.
| Assignee | Recent year | YoY |
|---|---|---|
| Qingdao Haier Washing Machine Co., Ltd. | 0 | — |
| SELF PROPELLED RES & DEV SPECIALISTS | 0 | — |
| Qingdao Haier Drum Washing Machine Co., Ltd. | 0 | — |
| Haier Group Corporation | 0 | — |
| LG Electronics Inc. | 0 | — |
| OKRUCH JR NICHOLAS | 0 | — |
| BEERS DAVID G | 0 | — |
| Haier Smart Home Co., Ltd. | 0 | — |
Where to take this from here
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, whitespace filing, or competitor tracking.
Check freedom-to-operate against the leading five assignees
With 63.3% of records held by five companies, any new cycle-design filing should be checked against that group's claim scope first, particularly around drying-time and energy-label control logic where D06F density is highest.
Run a freedom-to-operate check in EurekaDraft claims into the refrigeration-cycle gap
F25B classifications cover only 8.3% of records, well below the drying-process share. Evaporator frosting control and refrigerant charge optimisation are candidate areas for a first claim with less dense prior art to design around.
Explore whitespace claims in EurekaTrack the leading assignee's continuation filings
The top-ranked assignee's 18-record position and the recurring co-assignee pairings suggest an active internal filing programme worth monitoring for continuations that could narrow the refrigeration-cycle gap over time.
Set up assignee monitoring in EurekaCommon questions about this landscape
The leading assignee in this dataset holds 18 of the 120 records in scope, with a fifth-place company holding 13. The top five assignees combined hold 76 records, 63.3% of the field, so filing is concentrated among a small group of established appliance manufacturers rather than spread evenly. Anyone doing a freedom-to-operate review should start with that group before looking at the long tail of single-filing entrants.
Based on IPC classification, the drying process is far more heavily claimed than the refrigeration cycle mechanics. D06F (laundering, drying and ironing) appears in 86.7% of the 120 records, while F25B (refrigeration and heat pumps) appears in only 8.3%. That gap suggests refrigeration-cycle-specific claims, such as evaporator frosting control or refrigerant charge management, are comparatively less crowded than drying-control claims on the same appliance.
The most recent complete comparison in this dataset, 2021 to 2024, shows filings dropping from 3 to 1 records, a 67% decline. The field's recorded peak was 2017 at 6 records. However, because patent publication typically lags filing by around 18 months, the 2025 and 2026 figures are still incomplete and should not yet be read as confirmation of a continuing decline.
US8528227B2, assigned to Haier US Appliance Solutions and granted in 2013, covers a method of partitioning the energy available in a heat pump clothes dryer into two portions: one that maintains standard cycle performance and a second that energises an auxiliary heater during the start-transient phase to accelerate drying. It is one of the more cited records in this landscape and is a useful reference point for anyone claiming transient-phase acceleration techniques, since a competing claim would need to differentiate its energy-partitioning or heating mechanism from this approach.
The clearest gap by classification density sits in refrigeration-cycle-specific control: F25B, F25D and F04C together cover well under 15% of the 120 records, compared with 86.7% for general drying and laundering classifications. Practically, that points toward evaporator frost-sensing loops, compact-circuit refrigerant charge optimisation, and start-transient compressor ramp strategies as areas with fewer existing claims to design around, though any specific filing still needs its own novelty search.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.