This paper proposes SPArc_dl, an unsupervised deep learning model for rapid preselection of optimal energy layer (EL) sequences in proton beam therapy (PAT). To address the computational burden and extended treatment times compared to existing methods, we introduce a novel data representation, the spot count representation, which encodes the number of proton spots passing through the target and organs-at-risk (OAR). SPArc_dl, a U-Net architecture, is trained with a triple objective function: maximizing the number of target spots, minimizing the number of OAR spots, and reducing the EL switching time. Evaluation results using data from 35 pharyngeal cancer patients show that SPArc_dl improves both planning quality and delivery efficiency compared to the existing method, SPArc_ps. Specifically, it improves the fitness index by 0.1, reduces the homogeneity index by 0.71, reduces the mean brainstem dose by 0.25, and shortens the EL switching time by 37.2%. The inference time is less than 1 second, and we show that not changing the order of EL transitions is more time-efficient. However, the SPArc_dl plan shows limitations in robustness.