SOLIZE Intellectual Property Strategy Group
Introduction of Patent Inventions #1

This patented invention is a power transmission device in which the input torque passively changes in response to the magnitude of the load torque. The device is composed solely of mechanical elements—a spring and a lever mechanism—and does not rely on external sensors, electrical control, or actuators.

As load torque is applied, a compressive force acts on the spring, shifting the position of the input point, and thereby changing the input moment arm. As a result, an input torque corresponding to the load torque is generated purely through mechanical means.

Figure 1: Shows an example in which the present invention is applied to a fishing reel handle.
Figure 2: Illustrates the operating principle of the present invention.

When no-load torque is applied, the spring remains compressed only by its initial preload, without additional compression from load torque, and the input point is located closest to the rotational axis. Under this condition, the input moment arm L is at its minimum.

When a small load torque T₁ is applied, the compressive force f₁ = T₁ / r acts on the spring via portion P. However, because this compressive force is smaller than the restoring force corresponding to the initial spring preload, the position of the input point does not change substantially. As a result, the input moment arm L₁ remains small, and the input torque F · L₁ is also small.

When the load torque increases, the compressive force f₂ = T₂ / r acting on the spring exceeds the spring’s restoring force. As a result, the spring is compressed and the position of the input point shifts, causing the input moment arm L₂ to increase.

Consequently, even when the operator applies approximately constant input force F, the input torque F·L₂ increases automatically. In this way, the device mechanically generates sufficient input torque corresponding to load torque.

Expected applications include, but are not limited to, fishing reel handles; handles for hand-operated tools and daily-use devices (such as pencil sharpeners); bicycle pedals; kick-starter pedals; and a wide range of other manually operated rotational mechanisms.

For further technical details regarding this patented invention, as well as inquiries concerning licensing (grant of implementation rights), please contact the Marketing Department of SOLIZE PARTNERS Inc.

Contact: marketing.spt@solize.com

Title of the invention: Power Transmission Device

Patent registration number: JP 7823882

Filing date: July 25, 2022

Registration date: February 24, 2026

Patent link (Japanese): https://www.j-platpat.inpit.go.jp/c1801/PU/JP-2022-117879/10/ja

Patent link (English): https://www.j-platpat.inpit.go.jp/c1801/PU/JP-7823882/15/en

SOLIZE IP Reference number: SP22005

Patent holder (Patentee): SOLIZE Holdings Inc.

Inventor: Yosuke Momose (SOLIZE PARTNERS Inc.)